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The North American Diatom Symposium: A Little History The North American Diatom Symposium (NADS) is a biennial meeting normally held at field stations throughout the United States and Canada. The meeting was first held in 1970 at Cedar Creek in Minnesota. Since that date, the gathering has been hosted at field stations in Florida, Colorado, Manitoba, Kentucky, Alabama, Ohio, Minnesota, Iowa, Wisconsin, and Michigan. NADS usually attracts 80-100 diatomists from North America and around the world. The meeting provides a student friendly atmosphere, ample opportunities to network and socialize, the ever-popular scum run, local field collecting trips, and lively auction of diatom related valuables. NADS is an informal society, that is, there are no formal officers or structure. J. Platt Bradbury and Rick Drum organized the first NADS meeting. It was held in October 1970 at Cedar Bog Lake in central Minnesota (now the University of Minnesota's Cedar Creek Ecosystem Science Reserve). The site is notable for being the location of study for R. L. Lindeman’s classic paper “The trophic-dynamic aspect of ecology. Ecology 23:399-418”. The meeting was attended by 23 diatomists. After several days of discussion with no formal papers the group sat in a circle and talked about diatom ecology. This resulted in a paper (Bradbury, J. P. 1973. Ecology of freshwater diatoms. Nova Hedwigia. 24:145-168.), that was essentially a verbatim record of that conversation. This meeting provides the opportunity to catch up with colleagues and talk to some of the foremost diatom researchers in a beautiful, natural setting, offered by the field station atmosphere that has become a tradition at the symposium. This meeting provides the opportunity to catch up with colleagues and talk to some of the foremost diatom researchers in a beautiful, natural setting, offered by the field station atmosphere that has become a tradition at the symposium.

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About our Venue for 2015:

Central Michigan University Biological Station Central Michigan University Biological Station (CMUBS) is a state of the art research and educational facility that has been in existence for 60 years. CMUBS is located 5 miles south of the town St. James that is typical of any small Michigan town with 500 residents year round and more than 2,000 in the summer. Beaver Island is 58 square miles making it the largest of the 14 islands in this archipelago; the island supports 7 inland lakes and a diverse array of wetlands and coastal ecosystems. The island habitat is a mix between beach-maple climax forest and coniferous forests, that give way to an extensive cedar swamp to the south; this relatively pristine environment is home to an array of rare and endangered fauna and flora. The biological station on Beaver Island has been host to NADS once before in 1981 (September 9-12), and we are excited to once again serve as host for meeting on this picturesque island in Northern Lake Michigan 34 years later. Beaver Island is known to have a rich cultural environment and heritage. The first settlers on the island were thought to have pre-dated the settlement of the Pilgrims in North America (Swinehart, 1996 Proceedings of the Indiana Academy of Science. 105: 207-215). Beaver Island was once ran by a Mormon monarchy until the assassination of the king lead to Irish immigrants gaining control of the island (Swinehart, 1996). Beaver Island is now home to 500 residents year round with more than 2000 in the summer. The island is 58 square miles making it the largest of the 14 islands in this archipelago supporting 7 inland lakes and a diverse array of wetlands and coastal ecosystems. The island habitat is a mix between beach-maple climax forest and coniferous forests, that give way to an extensive cedar swamp to the south; this relatively pristine environment is home to an array of rare and endangered fauna and flora. CMUBS features a large auditorium, modern teaching laboratories, a series of research laboratories, and a unique mesocosm facility for conducting large-scale experiments. Research in coastal Lake Michigan is carried out aboard the 30 foot M/V Chippewa, a state of the art research vessel. The biological station on Beaver Island has been a host to NADS once before in 1981 (September 9-12), and we are excited to once again serve as host for meeting on this picturesque island in Northern Lake Michigan 30 years later.

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The NADS Organizing Committee for 2015:

Central Michigan University Biological Station

Hunter Carrick Biology Professor

Organizer for NADS 2015 Emon Butts Kimberly Carrick Student Assistant Student Assistant Mariena Hurley Kristy Phillips Graduate Student Assistant Graduate Student Assistant Gary Michaud Shayna Taylor Laboratory Technician Graduate Student Assistant John Gordon Melissa Schlict CMUBS Manager CMUBS Staff Daniel Benjamin Donna King Lab Coordinator Emeritus Biology Lecturer Emeritus Daniel Wujek Sarah Hamsher Biology Professor Emeritus NADS Webmistress

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The NADS Sponsors for 2015:

Central Michigan University Biological Station

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The NADS Program for 2015:

Central Michigan University Biological Station Time   Wednesday   Thursday   Friday   Saturday   Sunday  

700       Breakfast   Breakfast   Breakfast   Breakfast           Breakfast   Breakfast   Breakfast   Breakfast  

800       Phylogenics   Paleo   Great  Lakes   Departure  820       Phylogenics   Paleo   Great  Lakes      840       Phylogenics   Paleo   Great  Lakes      900       Phylogenics   Paleo   Great  Lakes      920       Phylogenics   Paleo   Great  Lakes      940       Break   Break   Break      1000       Population   Ecology   Methodology      1020       Population   Ecology   Methodology      1040       Population   Ecology   Plenary      1100       Population   Ecology   Methodology      1120       Population   Ecology   Plenary      1140       Population   Ecology          1200   Registration   Lunch   Lunch   Lunch      

        Lunch   Lunch   Lunch      1300       Plenary   Plenary   Business      

        Phylogeny   Metrics   Business      1340       Plenary   Plenary   Business      1400       Ecology   Ecology   Scum  Run      1420       Ecology   Metrics   Scum  Run      1440   Registration   Break   Break   Scum  Run      1500       Biochemistry   Metrics   Break      1520       Biochemistry   Metrics   Field  Trips      1540       Biochemistry   Metrics   Field  Trips      1600   Registration   Biochemistry   Metrics   Field  Trips      1620       Biochemistry   Metrics   Field  Trips      1700               Field  Trips      

                       1800   Dinner   Dinner   Dinner   Dinner      1900   Dinner   Dinner   Dinner   Dinner      2000   Mixer   Mixer   Mixer   Mixer      

    CMUBS   CMUBS   Shamrock   CMUBS           Opening     Posters   Party   Auction      

 

         

   

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10-Sep-15 THURSDAY TIME AUTHOR PRESENTRATION (SHORT TITLE) 700 Breakfast Breakfast 800 King et al. CONTRIBUTIONS OF MATTHHEW HOHN

820 Mengjie Anna Yu et al DIATOM EVOLUTION FROM DIATOM PLASTID GENOMES

840 Lefebvre & Hamilton STUDIES ON LARGE NEIDIUM SPECIES

900 Kociolek et al NATURAL CLASSIFICATION FOR THE DIATOMS

920 Theriot et al MODERN STEPHANODISCUS FLORA

940 Break Break 1000 Wu and Bergey FRESHWATER TURTLES AND THEIR EPIZOOIC DIATOMS

1020 Lowe et al. WILL THE REAL NAVICULA PERPUSILLA GRUN. STAND UP?

1040 Bishop and Spaulding POPULATION PATTERNS IN DIDYMOSPHENIA GEMINATA

1100 Burge et al. SEASONALITY AND ONTOGENY IN DIATOMA VULGARIS 1120 Pillsbury et al. VARIATION IN DIDYMOSPHENIA GEMINATA

1140 Furey BEAUTY OF ICELAND: SUBAERIAL ALGAL ASSEMBLAGES 1200 Lunch Lunch 1300 Kockiolek FRESHWATER DIATOM BIOGEOGRAPHY 2.0

1320 Plenary

1340

1400 Sweat et al. SHIP HULL TRANSPORT OF MARINE DIATOMS

1420 Hunsucker & Swain ADHESION OF DIATOMS TO SHIP HULL COATINGS.

1440 Break Break 1500 Gretz DIATOM EXTRACELLULAR POLYMERIC SUBSTANCES

1520 Nakamura et al. CHARACTERS OF CELL WALLS OF DIATOMS.

1540 Taylor et al. POLYPHOSPHATE ACCUMULATION IN BENTHIC BIOFILMS 1600 Rier et al. ROLE OF POLYPHOSPHATE IN THE PHOSPHORUS DYNAMICS

1620 Wee et al. RESPONSES OF SKELETONEMA COSTATUM

1640

1700     1800 Dinner Dinner

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11-Sep-15 FRIDAY TIME SPEAKER PRESENTRATION (SHORT TITLE) 700 Breakfast Breakfast 800 Chraibi & Fritz RESILIENCE OF LAKES IN YELLOWSTONE 820 Alexson et al. DIATOM RECORDS IN A GREAT LAKES ESTUARY

840 Edlund et al . PHOSPHORUS BUDGET FOR LAKE OF THE WOODS

900 Noble et al. TWO CENTURIES OF VARIATION IN DIATOMS

920 Warnock HOLOCENE HISTORY FROM THE BALTIC SEA

940 Break Break 1000 Clark & Bixby FIRE ASH IMPACTS ON DIATOM POPULATIONS 1020 Glass & Pillsbury SUCCESSIONAL OF EPIPSAMMIC COMMUNITIES

1040 Hurley & Carrick DIEL DISSOLVED OXYGEN SWINGS IN STREAMS

1100 Schulte & Gaiser RESPONSES TO P IN THE FLORIDA EVERGLADES

1120 Mayama & Nakamura ABUNDANCE OF EPIPSAMMIC COMMUNITIES

1140 Bixby et al. HARVEST METHODS AND DIATOM COMMUNITIES

1200 Lunch Lunch 1300 Stevenson et al. ALGAL BIOASSESSMENTS IN THE UNITED STATES

1320 Plenary

1340

1400 Lee et al. URBAN CHEMICAL STRESSORS ON STREAM BIOFILMS

1420 Hausmann et al. A DIATOM-BASED BIOLOGICAL CONDITION GRADIENT

1440 Break Break 1500 Manoylou et al. DIATOM ATTRIBUTES AND GEORGIA STREAMS

1520 Potapova et al. EUTROPHICATION OF NEW JERSEY COASTAL LAGOONS

1540 Carrick ALGAL METRICS FOR PENNSYLVANIA STREAMS

1600 Sgro & Reavie BENTHIC DIATOM METRIC FOR NEARSHORE LAKE ERIE

1620 Wolin et al. URBAN LAKE ASSESSMENT IN CUYAHOGA COUNTY, OHIO 1640 1700

 

   

    1800 Dinner Dinner

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12-Sep-15 SATURDAY TIME SPEAKER PRESENTRATION (SHORT TITLE) 700 Breakfast Breakfast 800 Phillips et al. CHLOROPHYLL IN SOUTHERN LAKE MICHIGAN 820 Butts et al. COMPOSITION OF PHYTOPLANKTON IN LAKE MICHIGAN 840 Carrick et al. PICO, NANO, AND MICROPLANKTON IN LAKE MICHIGAN

900 Reavie et al. CYCLOTELLA IN 90 % OF NORTH AMERICA’S SURFACE WATER

920 Bramburger et al. HISTORICAL “SHRINKAGE” IN GREAT LAKES DIATOMS?

940 Break Break 1000 Hamilton et al. DIATOM GENETIC STUDIES AND BARCODING

1020 Charles et al. DOCUMENTING AND ARCHIVING DATA FROM DIATOM STUDIES

1040 Millie & Weckman ROBO-ECOLOGY AND HAB PREDICTIVE ANALYTICS 1100 Plenary

1120

1140

1200 Lunch Lunch 1300 Edlund, Spalding NADS Business Meeting

1320

1340

1400 NADS Scum Run

1420

1440

1500 Break Break 1520 1540 Field Trips

1600 Botany of Beaver Island or

1620 Natural History of Beaver Island

1640 1700

    1800 Dinner Dinner

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Oral Presentation Abstracts The NADS Program 2015:

Central Michigan University Biological Station LONG-TERM DIATOM RECORDS TO SUPPORT DELISTING EFFORTS ON A GREAT LAKES ESTUARY Elizabeth E. Alexson1, Euan D. Reavie1, and Rich P. Axler1

1Natural Resources Research Institute, University of Minnesota Duluth, Duluth, MN 55811 The St. Louis River Estuary (SLRE) has a long history of human development since Euro-American settlement ~200 years ago. Due to degradation from logging, hydrologic modification, and untreated sewage from two major cities, the EPA designated the SLRE as an Area of Concern in 1987. Since then, government and private entities took action to restore water quality in hopes to eventually remove beneficial use impairments. However, due to a lack of historical data the extent of remediation is unknown, so a paleolimnological study of the SLRE was initiated to close the knowledge gap. Diatom assemblages were analyzed from six cores taken throughout the estuary. Preliminary results tell a complex story because of natural variability throughout the estuary, recent major storm events, and a continued industrial presence. Reductions in eutrophic taxa like Cyclotella meneghiniana and Stephanodiscus in certain cores suggest a recovery of water quality. However in other areas, persistence of Cyclostephanos dubius and Stephanodiscus binderanus, also eutrophic indicators, indicate continuing eutrophication. The diatom assemblages, integrated with other biological, chemical and physical indicators from the sediments, will aid agencies in determining where to target resources and delisting efforts. ________________________________________________________________________________________________________________________________________________________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________

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POPULATION-LEVEL PATTERNS OF SIZE DISTRIBUTION, REDUCTION AND RESTORATION IN THE NUISANCE DIATOM DIDYMOSPHENIA GEMINATA

Ian Bishop1 and Sarah Spaulding1

1Institute of Arctic and Alpine Research (INSTAAR), University of Colorado Boulder, Campus Box 450, Boulder, CO 80309-0450 USA.

The nuisance diatom Didymosphenia geminata has received much attention in the last 25 years, and considerable effort has gone into explaining both the origins and the ecological and economic consequences of its invasive behavior. Although the success of this species may be tied to its basic biology and life history, little is known about its population growth and reproductive dynamics. In this study, more than 100,000 individual cells were measured from populations of D. geminata over an annual cycle in South Boulder Creek, CO. Our objective was to implement FlowCAM technology and finite mixture modeling to uncover temporal patterns in cell size frequency, size restoration strategy, and potential synchronization of life cycles between populations in close proximity. We found that all populations examined exhibited a complex, multimodal size distribution containing an estimated 4 age cohorts throughout the year. While direct visual evidence of the sexual phase was not observed, directional shifts in size distribution indicate that size restoration events occurred in mid-summer (and possibly mid-winter too), which corresponds to earlier life history observations on the genus. Lastly, inter-populational synchronicity in size frequency was found to vary with river microhabitat, highlighting in the importance of considering spatial heterogeneity when observing in situ diatom size dynamics. This study is the first to document the complexity of diatom cell size distribution in a lotic system, size restoration in D. geminata, and the variability in rates of size reduction among different habitats. This research demonstrates the utility of FlowCAM analysis and mixture modeling in diatom size reduction studies, and offers a new methodological approach to such study.

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EFFECTS OF FOREST HARVEST METHODS ON DIATOM COMMUNITIES IN HEADWATER STREAMS

Rebecca Bixby1, Sherri Johnson2,3, and Linda Ashkenas3

1Department of Biology and Museum of Southwestern Biology, University of New Mexico, Albuquerque, NM 87131 USA 2PNW Research, U.S. Forest Service, Corvallis, OR 97331 USA 3Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR 97331 USA In many lower order streams, general thought is that a reduction in riparian cover and subsequent increases in light and temperature results in increased algal biomass and shifting community composition of algal taxa. In headwater streams in the Trask River watershed, Coast Range, Oregon, research is ongoing and examining the impact of forest harvesting practices on whole watershed parameters. Here, we focused on primary producer responses to reduction or removal of riparian buffers and subsequent increases in light and temperature. Data were collected per-harvest (2008-2011) and post-harvest (2013) from five sites with three harvest treatments (clearcut, no buffer; clearcut, leave trees near stream; clearcut; riparian buffer) and reference reaches. Chlorophyll a (=algal biomass) and algal community composition, abundance, and biovolume were analyzed. Chlorophyll a was not significantly different among all treatments when comparing pre- and post-harvest. The five streams had surprisingly different baseline diatom communities, given the spatial proximity of the streams, dominated by combinations of Achnanthidium minutissimum, Diatoma mesodon, Gomphonema minutum, Meridion circulare, Planothidium lanceolatum, and Rhoicosphenia abbreviata. Streams with clearcuts but intact riparian buffers had significant increases in P. lanceolatum while R. abbreviata decreased in abundance. In the clearcut stream with no buffer, diatom communities were highlighted by an increase in species diversity and a shift in diatom dominance towards more tolerant taxa. Further work is needed to incorporate biovolume parameters which have been shown to have a strong response in deforestation studies. These wide-ranging results, with no significant chlorophyll measures among treatments but mixed diatom community change, illustrate the complex response of algae to riparian removal and emphasizes the necessity for stream buffers to protect stream food webs and ecosystems during timber harvest. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ________________________________________________________________________

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LIKE A FRIGHTENED TURTLE: HISTORICAL “SHRINKAGE” IN GREAT LAKES DIATOMS? Andrew J. Bramburger1, Euan D. Reavie1, Gerald V. Sgro2, Lisa R. Estepp1, Victoria L. Shaw Chraïbi3, and Robert W. Pillsbury4

1Natural Resources Research Institute, University of Minnesota Duluth, Duluth, MN 55811 USA 2John Carroll University, University Heights, OH 44118 USA 3University of Nebraska-Lincoln, Lincoln, NE 68588 USA 4University of Wisconsin Oshkosh, Oshkosh, WI 54901 USA 5NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, MI 48105 USA Diatom frustule size can be influenced by a variety of factors, including seasonal succession, water quality, and life cycle effects. We examined patterns of diatom frustule size (individual biovolume) in samples from a series of cores spanning the Laurentian Great Lakes dating back ~150 years. In general, diatom size has remained relatively constant, and no significant size/date relationships exist across all lakes, or within Lakes Erie and Ontario. However, in the upper Great Lakes (Superior, Michigan, Huron), mean individual biovolume has been decreasing slowly but steadily since the mid-1800s. While the relative influences of compositional shifts in the assemblage and taxon-specific changes in frustule size are not yet fully understood, preliminary analyses suggest that while many taxa do not exhibit changes in frustule size, Cyclotella sensu lato species have been shrinking across the Great Lakes. These findings, coupled with an apparent climate-induced rise in Cyclotella densities over the last several decades, suggest that shrinkage within this genus is contributing to overall reduction in mean frustule size within the Great Lakes basin. Mechanisms responsible for this shrinkage are under investigation, but size-specific distribution within stratified Great Lakes water columns (e.g. occupation of epilimnion versus metalimnion) suggests that smaller frustule size my help to mitigate sinking rates in response to warmer, less dense epilimnetic waters. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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SEASONALITY AND ONTEGENY IN DIATOMA VULGARIS David Burge1, Ian Bishop2, Natalie Hoidal3, Mark Edlund1, and Marina Potapova4

1St. Croix Watershed Research Station, Science Museum of Minnesota, Marine on St. Croix, Minnesota, 55047, USA 2 Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado, 80303, USA 3 University of Minnesota, Morris, Minnesota, 56267, USA 4 Academy of Natural Sciences of Drexel University, Philadelphia, 19104, USA Morphology remains the foundation of diatom taxonomy. Therefore, when characterizing a species it is important to understand seasonal, ecophenotypic, and allometric morphological variation. Knowledge of morphotypes can also be important when describing autecological information about a species. Over three summers, Diatoma vulgaris was studied in situ from the epilithon of East Lake Okoboji, Iowa, USA. Populations were observed undergoing annual size restoration in the spring followed by size diminution during the summer. Using Relative Warps shape analysis, allometric trends characterized the variation in valve morphology associated with size diminution and seasonality. The allometric trends were further compared with taxa in the literature that have been reported as separate taxa, varieties, and morphotypes within Diatoma. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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TAXONOMIC COMPOSITION OF NEAR VERSUS OFFSHORE PHYTOPLANKTON IN LAKE MICHIGAN: CAN EPISODIC EVENTS PROMOTE DIATOM GROWTH? Emon K. Butts1, Kristy Phillips1, Henry Vanderploeg2, and Hunter J. Carrick1

1Dept. of Biology & Institute for Great Lakes Research, Central Michigan University, Mt. Pleasant, MI 48859 USA 2 National Oceanic and Atmospheric Administration, Great Lakes Environmental Research Lab., Ann Arbor, MI 48104 USA Observations of Lake Michigan’s phytoplankton community have revealed considerable changes in its overall composition and typical seasonal succession patterns, particularly the significant decline of the annual spring diatom bloom. Lake Michigan was sampled in 2013 and 2015, at both near (depth 15m) and offshore (depth 110 m) stations along an East-West transect offshore from Muskegon, Michigan’ this transect has been monitored long term (NOAA-GLERL). Surface water (5m) was sampled at both the near and offshore stations and aliquots were used to preserve phytoplankton for subsequent enumeration. The phototrophic picoplankton (cells <2um in size, Ppico) and nanoplankton (cells 2-20 um in size, Pnano) were identified and enumerated using epiflourescence microscopy (Leica DMR 5000) while larger microplankton (i.e. cells > 20 um in size) were enumerated with the Utermöhl technique using an inverted microscope (Leica DMI 4000). Also aliquots were used to filter for extracted chlorophyll-a corrected for phaeo-pigments. Chlorophyll concentrations exhibited considerable variation among sampling events (10.7-0.48 ug/L) and were greater at the near shore station (3.2 ug/L +/- 3.3) compared with offshore (1.6 ug/L +/- 1.1). Phytoplankton carbon was composed of mixed assemblage of cryptophytes (60.2 +/- 26.2%), chrysophytes (17.0 +/- 13.3%), diatoms (4.6 +/1 4.3), and others (14.5 +/- 15.2). There were no strong spatial variation in phytoplankton carbon between near and offshore stations (one-way MANOVA F= 1.092, p= 0.607); however in 2013, diatoms were present in near shore samples during the spring period and in the deep chlorophyll layer in July. A cluster analysis revealed discernable differences in phytoplankton taxonomic composition between 2013 and 2015. We hypothesize the extreme rainfall event in spring 2013 caused a large runoff event initiated a diatom bloom in the near shore that may have seeded diatom growth several months later in the offshore, subsurface layer. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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ALGAL METRICS AND THE DETERMINATION OF NUTRIENT CRITERIA FOR PENNSYLVANIA STREAMS Hunter J. Carrick1

1Department of Biology & Institute for Great Lakes Research, Central Michigan University, Central Michigan University, Mount Pleasant, MI 48859 Numeric nutrient criteria are an effective tool for preventing nutrient pollution to streams and rivers, as well as, deriving numeric limits for discharge to surface waters in the USA. Elevated material loading are often tied to changing land-use (urban and agricultural practices); these changes have had a measurable effect on aquatic ecosystems throughout the mid-Atlantic region, where more than 2,500 miles of native stream receive some degree of impact in Pennsylvania alone. In this paper, I present and discuss potential biological metrics that show promise in determining nutrient criteria for streams. A comprehensive survey of 97 streams in Pennsylvania was carried out between 2005-14. Benthic chlorophyll concentrations exhibited a large range among the streams (10-1,000 mg/m2). The regression models explained nearly 50% of the variation in chlorophyll using simple water quality parameters (singly for TN, TP); the P regression improved when nutrients in the benthic mat were incorporated. P-uptake capacity of stream biofilms was quantified to known P-loadings (using radiotracer experiments), whereby P-uptake rates decreased with P-loading and the regression slopes also declined with increasing stream productivity. Conversely, poly-P content in the biofilms was positively related to P loading (range in r2 0.67 to 0.92), indicating its promise as a biochemical metric. Diatom taxonomic composition varied among streams, whereby unique assemblages were observed from low (e.g., Achnanthidium, Cymbella) versus high (e.g., Navicula, Nitzschia) productivity streams. A third group of diatoms was identified that may reflect physical disturbance conditions (species of Cocconeis). Thresholds based upon diatom nutrient guilds determined for the Piedmont streams were more than 3-fold higher for TP and TN (52 +/- 22 µg/L and 1,560 +/- 228 µg/L) compared with those estimated for Plateau streams (TP 16 +/- 3 µg/L and TN 460 +/- 33 µg/L). The nutrient thresholds presented here are best thought of as ecological relationships that can inform the development of nutrient criteria (and ultimately nutrient load limits) for streams in Pennsylvania. ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________

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VARIATION IN THE ABUNDANCE OF PICO, NANO, AND MICROPLANKTON IN LAKE MICHIGAN: HISTORIC AND BASIN-WIDE COMPARISONS Hunter J. Carrick1, Emon K. Butts1, Daniella M. Daniels1, Melanie Fehringer1, Christopher Frazier1, Gary L. Fahnenstiel2, Steven Pothoven3, and Henry A. Vanderploeg3 1Department of Biology & Institute for Great Lakes Research, Central Michigan University Biological Station, Central Michigan University, Mount Pleasant, MI 48859 2Great Lakes Research Center and Michigan Technological Research Institute, Michigan Technological University, Houghton, MI 49931 Water Center, University of Michigan, Ann Arbor, MI 48105 3Great Lakes Environmental Research Laboratory, National Oceanic and Atmospheric Administration, Ann Arbor, MI 48104 The Lake Michigan ecosystem has undergone numerous, systemic changes (reduced nutrient loading, changing climate, proliferation of invasive mussels) that have altered portions of the food web and thus, appear to have changed the lake’s trophic state. That said, little is known about the components of the microbial food web (MFW, heterotrophic and phototrophic pico, nano, and micro-plankton), which we hypothesized have compensated as a food source for crustacean zooplankton given the recent declines in the biomass of large phytoplankton (mainly diatoms in the microplankton size category). Therefore, we measured the abundance of the entire MFW using complimentary microscopic techniques, flow cytometry, and size fractionated chlorophyll concentrations at sites in northern and southern Lake Michigan, and one site in Lake Superior; the later site served as a benchmark for oligotrophic conditions. In addition, a historic comparison was made between 1987 and 2013 for the southern Lake Michigan site. Ppico numbers (i.e., picocyanobacteria) in 2013 were lower compared with those in the 1980’s; however, the percent contribution of the <2µm fraction increased 2-fold (> 50% of total chlorophyll). The abundance of small, pigmented chrysomonads and cryptomonads (Pnano size category) were not significantly different between 1987 and 2013 at the same time Pmicro did decline; this shift towards Ppico and Pnano dominance may be related to the recent oligotrophication of Lake Michigan. The abundance of ciliated protists (Hmicro size class) was 3-fold lower in 2013 compared with levels in 1987, while the abundance of both Hpico (eubacteria, range 0.24-1.36 x 106 cells • mL-1) and Hnano (mainly colorless chrysomonads; range 0.11-6.4 x 103 cells • mL-1) remained stable and reflected the resilience of bacteria-flagellate trophic linkage. ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________

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DOCUMENTING AND ARCHIVING DATA FROM DIATOM ECOLOGICAL STUDIES: SOME GUIDELINES Donald Charles1, Sonja Hausmann1, and Chris Vito1 1Phycology Section, Patrick Center for Environmental Research, Academy of Natural Sciences of Drexel University, Philadelphia, PA 19103, USA. Thousands of diatom samples are analyzed each year by many analysts. Resulting counts and associated data provide important information about diatom ecology, aquatic ecosystems and the influence of human activities. These data are potentially useful beyond the purpose for which they were created, but most are not readily available to other researchers. Funding agencies are more frequently requiring that data be archived and made publically available. One reason more data are not available is the general lack of standard guidelines on what data should be included and in what format. Based on our experience caring for diatom data over many years, and review of several diatom databases, we suggest guidelines to help make to diatom datasets more accessible. They are generally applicable to most existing databases. We summarize major principles, formats and documentation procedures for existing larger datasets (e.g., Neotoma paleoecology; ANSP, US EPA, USGS BioBase, various states; European datasets). We provide basic guidelines for site location, taxonomy, counts, metrics / inferred values; and site / environmental characteristics. Data formats should be easily accessible by other users, convertible to other formats; and clearly documented. We recommend that data documentation and formatting be planned at the beginning of projects; data archiving will be much easier and more successful. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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RESILIENCE OF AQUATIC COMMUNITIES IN NATURALLY FISHLESS LAKES IN YELLOWSTONE NATIONAL PARK TO FISH STOCKING Victoria L. S. Chraïbi1 and Sherilyn C. Fritz1

1Department of Earth and Atmospheric Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588, USA For up to 75 years, many of the naturally fishless lakes in Yellowstone National Park were stocked with 18 species of fish, six of which were non-native. In the 60 years since the fish-stocking program ended, some lakes have returned to a fishless state, while other lakes continue to independently maintain populations of fish. This study uses a paleoecological approach to evaluate how and why these lakes responded differently to the introduction of a higher trophic level. Using fossil diatom, zooplankton, and invertebrate assemblages and historical records of fish stocking, we are reconstructing the lower trophic levels of the food web of each lake before, during, and after fish stocking to examine how the introduction of new predatory species affected the trophic structure. The lakes in this study are grouped into paired replicates, including control lakes that were never stocked, to evaluate how abiotic characteristics, such as lake morphology, bedrock, and regional microclimate, influence the resilience of the biotic community. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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FIRE ASH IMPACTS ON DIATOM POPULATION GROWTH: A MICROCOSM STUDY

Alexander L. Clark1 and Rebecca J. Bixby1

1Department of Biology, University of New Mexico, Albuquerque, New Mexico 87131 USA

Fire is an important ecological impact on many terrestrial environments, resetting the growth of the ecosystem to an early successional stage. Additionally, even when a burned region in a watershed and river are spatially disconnected, the mobilization of ash during rain events can negatively impact water quality, decreasing pH and dissolved oxygen concentrations while increasing conductivity and turbidity of the water. Few studies have examined the impacts of fire ash on water quality and even fewer on the impacts of primary producers. The objective of this study was to experimentally determine if fire ash leachates, and the associated change in pH, cause a positive fertilization effect on different taxa of diatoms with different life histories. Six tree species were burned to produce ash, which was mixed with deionized water to extract the water-soluble components and then filtered. Four species of diatoms (Cocconeis placentula var. lineata, Staurosira construens, Gomphonema truncatum, and Rhopalodia gibba) were cultured in CR1 and CR1-S diatom media. Treatments were designed using the following scheme: 1) Tree ash leachate (6 tree species, mixed with media), 2) Control (diluted media), and 3) Control (pH-adjusted to match leachate) for a total of eight treatments. Each diatom species was grown in replicate for eight days and enumerated using a Palmer-Maloney cell and light microscopy. Preliminary analysis of R. gibba cultures indicated a decreasing trend in cell densities due to each ash treatment, with an increase in the cell densities of the pH-adjusted treatment. Further analysis is needed on the remaining three species for determining differences in final cell densities as well as investigation into possible mechanisms other than pH that impacted the growth of the R. gibba cultures. Known differences in the alkalinity of the ash leachates or the conductivity of the treatments may prove to be possible explanations for changes in the diatom growth rates. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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A HISTORICAL PHOSPHORUS BUDGET FOR LAKE OF THE WOODS: LEGACY LOADS STILL AFFECT THE SOUTHERN BASIN Mark B. Edlund1, Euan D. Reavie2, Shawn Schottler1, Nolan Baratono, N.4, Andrew M. Paterson, A.M.3, and Daniel R. Engstrom1 1St. Croix Watershed Research Station, Science Museum of Minnesota, Marine on St.

Croix, MN 55047 2Center for Water and the Environment, Natural Resources Research Institute, University

of Minnesota Duluth, 1900 East Camp Street, Ely, MN 55731 3Dorset Environmental Science Centre, Ontario Ministry of the Environment, 1026

Bellwood Acres Road, P.O. Box 39, Dorset, ON, P0A 1E0 4Minnesota Pollution Control Agency (retired), 909 Riverside Drive, International Falls,

MN 56649 Using basin-wide paleolimnological analyses, a historical phosphorus (P) budget was constructed for Lake of the Woods (LoW; Minnesota-Ontario). Sediment cores from seven bays were analyzed for radioisotopic dating, geochemistry (loss-on-ignition, phosphorus, silica), diatoms, and pigments. Pigments show increasing concentrations since damming through 1970, decreases in the 1980s, and increases again in the last 15 years. Diatoms suggest increased productivity and increased water column TP upcore with greater abundance of eutrophic species. Geochemical records were combined using sediment focusing factors to provide whole-basin estimates of the accumulation of bulk sediment, total phosphorus, and refractory and labile phosphorus fractions. Although historical estimates show that P loading is reduced since the 1960s, sediment phosphorus concentration and accumulation increase upcore. A substantial proportion of exchangeable and mobile P fractions suggests that a large pool of mobile sediment P is available for exchange. Several models were used to explore historical P loading scenarios and in-lake nutrient dynamics. Key results include, first, that P loadings were approximately 646 t P/yr before damming, nearly as high as current loadings. Second, burial rates of refractory P are increasing in LoW compared to pre-damming levels. Third, the labile P pool can only be accounted for if historical loading was larger. Fourth, the active P pool was much larger and at maximum size in the 1970s. Fifth, the legacy pool is currently being depleted to support modern levels of productivity. Last, the rate at which the pool is being depleted varies among models, but shows rapid depletion since the 1970s. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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BEAUTY OF ICELAND: A GUIDED TOUR OF SUBAERIAL ALGAL ASSEMBLAGES P.C. Furey1

1 Department of Biology, Saint Catherine University, St. Paul, Minnesota, 55105, USA

Subaerial environments support a unique algal flora that takes advantage of microhabitats that vary with geology type, moisture level and surface topography. The subaerial diatom assemblages from volcanic rock outcrops in Iceland remain understudied. The biodiversity of a variety of subaerial environments was explored from the Hengill area, 30 km east of Reykjavík, and the rift valley in, Þingvellir National Park. Diatom assemblages were collected by squeezing material from bryophytes or by scraping rock with a spoon and pipette. Light and scanning micrographs showed internal and external morphological and ultrastructural features of the frustules. Your tour of these beautiful Icelandic diatoms begins with gorgeous landscape views to introduce the habitats and then proceeds to an image rich presentation of subaerial taxa from genera such as Humidophila, Eunotia, and Orthoseira. The biodiversity and ecology of these diatom assemblages is discussed in relation to the flora of wet walls from other locations. This diatom tour will leave you wanting to visit Iceland to explore more of the subaerial diatom world.

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THE IMPORTANCE OF NUTRIENTS ON THE SUCCESSIONAL PATTERNS OF THE EPIPSAMMIC COMMUNITY OF DOUGLAS LAKE, MI

Brenna Glas1 and Robert Pillsbury1

1Biology Department, University of Wisconsin Oshkosh, Oshkosh, Wisconsin 54902, USA

Epipsammic algae (algae living between sand grains) is an under studied community that can be an important part of the food web in many lake ecosystems. In general, eutrophication trends worldwide are increasing the levels of nitrogen and phosphorous in the water column. Douglas Lake, MI (a mesotrophic lake with a substantial, sandy, littoral zone) offered the perfect setting to quantify how epipsammic algae are affected by this change in nutrient availability. Enclosures were used on clean sand to subject colonizing algae to different nutrient treatments (P additions, N additions, N+P additions, and control). Cores were taken once a week for three weeks, algal cells were identified to genus and counted at three separate depths. We compared community shifts among treatment over time by analyzing data using Principal Component Analysis (PCA). The cores were also compared to epipelic algae samples collected in each enclosure to quantify differences in successional patterns between epipelic and epipsammic communities. How these patterns fit into the overall process of lake eutrophication will be discussed.

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DIATOM EXTRACELLULAR POLYMERIC SUBSTANCES Michael R. Gretz1

1Department of Biological Sciences, Michigan Technological University, Houghton, MI 49931 USA Diatom extracellular polymeric substances (EPS) have gained a degree of notoriety of late with the emergence of Didymosphenia geminata as a nuisance species. Didymo produces huge amounts of EPS in the form of stalks with significant impact on streams worldwide. It is feasible that, at any time, other diatoms may follow suit and ramp up EPS production to the prodigious levels accomplished by Didymo. In order to prepare for such an event it is prudent to review the forms of diatom EPS and the predicted and realized structure/function/impact of each. A mini-update of our diatom EPS review in the Journal of Phycology ~20 years ago will be presented. I am amassing amazing but true diatom EPS stories. If you have one please let me know. ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________

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A COMPREHENSIVE APPROACH TO DIATOM TAXONOMIC GENETIC STUDIES AND BARCODING FROM SINGLE CELL PCR AMPLIFICATIONS USING FRESH AND PRESERVED SAMPLES Paul B. Hamilton1, Keely E. Lefebvre 1, 2, and Roger D. Bull1

1Research and Collections, Canadian Museum of Nature, P.O. Box 3443, Station D., Ottawa, Ontario K1P 6P4 Canada 2University of Ottawa, Ottawa, Ontario K1N 6N5 Canada Single cell Chelex® DNA extraction and nested PCR amplification were used to examine partial gene sequences from natural diatom populations for taxonomic and phylogenetic studies at and above the level of species. DNA was extracted from cells that were either fresh collected or stored in RNAlater. Extractions from Lugol’s fixation were also attempted with limited success. Three partial gene sequences (rbcL, 18S and psbA) were recovered using existing and new primers with a nested or double nested PCR approach with amplification and success rates between 70–96%. An rbcL consensus tree grouped morphologically similar specimens and was consistent across the two primary sample treatments: fresh and RNAlater. This tool will greatly enhance the number of microscopic diatom taxa (and potentially other microbes) available for barcoding and phylogenetic studies. The near-term increase in sequence data for diatoms generated via routine single cell extractions and PCR will act as a multiproxy validation of longer-term next generation genomics. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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A DIATOM-BASED BIOLOGICAL CONDITION GRADIENT (BCG) APPROACH FOR ASSESSING IMPAIRMENT AND DEVELOPING NUTRIENT CRITERIA FOR STREAMS Sonja Hausmann1, Donald Charles1, Thomas Belton2, and Jeroen Gerritsen3

1Phycology Section, Patrick Center for Environmental Research, Academy of Natural Sciences of Drexel University, Philadelphia, PA 19103, USA. 2Office of Science, Department of Environmental Protection New Jersey, Trenton, NJ 08608, USA. 3Tetra Tech, Inc., Owings Mills, MD 21117, USA. The US Environmental Protection Agency (EPA) worked with biologists from across the United States to develop the Biological Condition Gradient (BCG) conceptual model which provides the basis for scientifically defensible regulatory guidelines for aquatic life designated uses and biotic integrity (Davies and Jackson, 2006). The BCG categories represent a range of ecological conditions from natural (1) to highly disturbed (6). To date, the BCG has been applied primarily to macroinvertebrates and fish. Our group expanded this approach to periphytic diatom communities (Charles et al., 2010). A panel of experts on use of diatoms as ecological indicators, assigned each taxon to one of six ecological BCG attributes and assigned 57 river and stream sites in five ecoregions throughout the state of New Jersey (NJ), USA to BCG categories based on diatom assemblage composition. Rules were developed that could be used to assign new diatom samples to BCG categories. An independent follow-up study was performed to test these rules. Data collected from an additional 42 sites in northern NJ were analyzed using the same procedures as the first study (Gerritsen et al., 2014). The U.S. Environmental Protection Agency (EPA) requires that states develop numerical nutrient criteria. To develop potential nutrient criteria, we explored the relation of BCG scores to nutrient concentrations, other anthropogenic stressors, and possible confounding variables. In NJ BCG scores correlated most strongly with total phosphorus (r = 0.69) and the percentage of forest in the watershed (r = -0.62), but were independent from pH. To determine if there were BCG change-points based on diatom assemblages using a numerical zonation procedure and Threshold Indicator Taxa Analysis (TITAN) we explored significant changes in the diatom communities of the 42 sites in NJ along the BCG gradient. The results indicated significant diatom changes at a BCG score near, but better than 4, which is defined by moderate changes in structure & minimal changes in function. Sites with BCG scores better than 4 were dominated by attached Achnanthidium species, while sites with BCG score of 4 or poorer were dominated by motile species such as Eolimna minima and Nitzschia inconspicua. Sites with a BCG score near 4 can be considered sites in transition and need attention to prevent impairment, while sites with better BCG scores need protection to stay unimpaired. The BCG approach is very promising and is helping to establish nutrient criteria in New Jersey. ________________________________________________________________________________________________________________________________________________________________________________________________________________________ ________________________________________________________________________

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STATIC VS DYNAMIC SETTLEMENT AND ADHESION OF DIATOMS TO SHIP HULL COATINGS.

Kelli Z. Hunsucker1 and Geoffrey W. Swain1

1Center for Corrosion and Biofouling Control, Florida Institute of Technology, Melbourne, Florida 32901 USA. Many experiments utilize static immersion tests to evaluate the performance of ship hull coatings. These provide valuable data, however, they do not accurately represent the conditions both the hull and fouling organisms encounter while a ship is underway. This study investigated the effect of static and dynamic immersion on the adhesion and settlement of diatoms to one antifouling coating (BRA 640), four fouling-release coatings (Intersleek® 700, Intersleek® 900, Hempasil X3, and Dow Corning 3140) and one standard surface (Intergard® 240 Epoxy). Differences in community composition were observed between the static and dynamic treatments. Achnanthes longipes was present on all coatings under static immersion, but was not present under dynamic immersion. This was also found for diatoms in the genera Bacillaria and Gyrosigma. Melosira moniformis was the only diatom to be present under dynamic conditions, but not static conditions. Several common fouling diatom genera were present on panels regardless of treatment: Amphora, Cocconeis, Entomoneis, Cylindrotheca, Licmophora, Navicula, Nitzschia, Plagiotropis and Synedra. Biofilm adhesion, diatom abundance and diatom diversity were found to be significantly different between static and dynamic treatments, however, the difference was dependent on coating and sampling date. Several coatings (Epoxy, DC 3140 and IS 700) had significantly higher biofilm adhesion on dynamically treated panels on at least one of the four sampling dates, while all coatings had significantly higher diatom abundance on at least one sampling date. Diversity was significantly greater on static panels than dynamic panels for Epoxy, IS 700 and HX3 at least once during the sampling period. The results demonstrate how hydrodynamic stress will significantly influence the microfouling community. Dynamic immersion testing is required to fully understand how antifouling surfaces will respond to biofilm formation when subjected to the stresses experienced by a ship underway. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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DIEL DISSOLVED OXYGEN SWINGS IN STREAMS (PENNSYLVANIA, USA): IMPORTANCE OF BENTHIC PRIMARY PRODUCTION & NUTRIENTS Mariena K. Hurley1 and Hunter J. Carrick1

1Department of Biology, Institute for Great Lakes Research, Central Michigan University, Mount Pleasant MI 48858 The Susquehanna River is the largest river in the eastern US (747 km), spanning from New York to the Atlantic Ocean by way of the Chesapeake Bay. Excessive watershed loadings of nitrogen and phosphorus have led to undesirable changes in diel oxygen swings and fish production in both the river and the bay. Dissolved oxygen swings are generally affected by physical-chemical conditions of the water column (e.g. nutrient concentrations, river flow, and temperature) and contributions from benthic production-respiration. Aquatic ecosystems experience diel oxygen changes regularly to help maintain their development and survival through changes in photosynthesis and respiration between day and night. A series of enclosed and controlled experiments of varying light intensity (7, 16, 120, 1,193 µE/m2/s) were performed across 12 streams of varying trophic states to determine a relationship between the natural benthic biofilms production and the diel oxygen swings recorded by sondes. Each set of samples was incubated in the enclosed light box for four hours, after which the Winkler titration method was performed to determine each sites oxygen production. The experimental primary production varied greatly among the streams (99-5707 mg O2/m2/h) matching the determined chlorophyll-a (34-245 mg/m2). Production was different between the four light levels (one-way ANOVA F= 17.44, p=0.000), with the higher light intensities promoting positive production and the dark treatments negative production or respiration; these patterns agreed closely with the trend of the diel oxygen swings measured in the streams. Total phosphorus (TP) in the benthic biofilm had a strong, positive relationship with light-saturated production, exhibiting greater predictability compared with conventional chlorophyll-nutrient regressions (r2= 0.92). Given the strong correlation between benthic biofilm TP and primary production, it stands to reason that biofilm TP content could drive significant oxygen production in these streams through increased primary production; therefore, enhancing large dissolved oxygen swings in streams. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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CONTRIBUTIONS OF MATTHEW H. HOHN TO DIATOMS AND THE CENTRAL MICHIGAN UNIVERSITY BIOLOGICAL STATION Donna K. King1, Daniel E. Wujek1, and Hunter J. Carrick1

1Department of Biology, Central Michigan University, Mount Pleasant, MI 48459 Matthew H. Hohn graduated with an undergraduate degree in education in 1945 from Indiana State University, PA. After teaching high school science and biology for one year, he enrolled in graduate school at Cornell University where be became interested in diatoms and completed M.S. and Ph.D. degrees. In 1952 through 1959 he continued his work with diatoms as an assistant curator at the Academy of Natural Sciences in Philadelphia as an associate curator. He then taught at Bloomsburg State University, Pennsylvania as an associate professor. In 1961 he accepted a faculty position in the Department of Biology at Central Michigan University. In 1965 he was promoted to full professor and assumed the position of coordinator of the CMU Biological Station on Beaver Island. During his tenure as coordinator, he was instrumental in transforming an administrative retreat into an academic unit dedicated to quality education and research in the biological sciences. His publications included 27 scholarly works in the disciplines of botany, limnology, and phycology. These works include extensive surveys of diatoms in Canada, Peru, South America, the Great Lakes, and the large rivers systems throughout the United States. He mentored many students including 17 Master of Science students who completed theses under his advisement. He retired in 1986 and chose to live with his wife Eleanor on Beaver Island. Matthew died on March 18, 1999; the dining hall at CMUBS on Beaver Island bears the Hohn name in memory of his service to excellence in biological research and education. The diatom Sellaphora hohnii was named in his honor. ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________

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FRESHWATER DIATOM BIOGEOGRAPHY 2.0

J.P. Kociolek1

1Museum of Natural History and Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, 80309 USA

This address looks at the changes that have occurred over the past 25 years in the area of freshwater diatom biogeography. This research topic has changed from one where the dogma of cosmopolitanism was widely embraced and integrated into approaches to taxonomy, to a vital field of research. The state of play is summarized beginning at ca. 1991 (the year of publication of the fourth volume diatom volume in the Susswasserflora von Mitteleuropa series). The 2000 paper “Freshwater Diatom Biogeography” is revisited and subsequent papers on this topic are discussed, including whether cosmopolitan species actually exist and the possible vectors for their dispersal. Today, the idea that diatom species, and their distributions, are related to historical processes (evolution, geologic) is widely accepted, with the most visible outcome of this intellectual embracement being the large number of endemic species described and (much) smaller number of works describing patterns in spatial distributions. The field has moved significantly in the past 25 years, showing that patterns of diatom distributions exist and, like other groups of the biotic world, can be attributed to historical processes.

The “2.0” aspect of the title of this talk deals with possible areas of future research focus in the realm of questions dealing with diatom biogeography. Areas that seem ripe for future (short-term) research emphasis include: 1) documenting the diatom flora of areas and habitats that are not yet well described, 2) exploring whether species flocks exist in diatoms, 3) shifting focus from describing species to focusing on monophyletic groups of species and a faster pace (than seen currently) to describing new genera, and 4) seeing if patterns of geographic distribution documented for other groups of organisms can also be observed in freshwater diatoms.

Areas and habitats that have born or may hold some interesting results in terms of species and other monophyletic groups are presented, such as Australia, certain island systems and wet walls. Putative species flocks are discussed and others are introduced as examples of this evolutionary phenomenon (and where one might look to find them in the future). The disparity between the numbers of diatom genera relative to species is illustrated, with a view to better understanding the relationships of freshwater ecosystems. Finally, an example is given exploring biogeographic patterns in SE Asia, with two diatom genera used as proxies, to see if freshwater diatoms adhere to Wallace’s Line.

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TOWARDS A NATURAL CLASSIFICATION FOR THE DIATOMS

J.P. Kociolek1,2, E.C. Theriot3,4, M.P. Ashworth3, and D.M. Williams5 1Museum of Natural History and 2Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, 80309 USA 3Texas Natural Science Center and 4Department of Integrative Biology, College of Natural Sciences, University of Texas, Austin, TX 78712, USA 5Department of Life Sciences, Division of Genomics and Microbial Biodiversity, The Natural History Museum, Cromwell Road, London, SW7 5BD, United Kingdom There have been many proposed classification schemes to organize the immense diversity seen in the diatoms. Some of these schemes or systems have been based on convenience, that is, to identify certain groups and distinguish them from others without an interest in representing evolutionary history. Other systems have attempted to produce ‘natural’ classifications, those systems reflecting the evolutionary history or phylogenetic relationships of the diatoms. Developing an understanding of the evolutionary history of the group has taken several quite different approaches. One approach has sought out a “Silver Bullet”, a single feature around which a classification can be based. Examples of this approach have been focused on valve (e.g. symmetry), cytoplasmic (chloroplast number, morphology and orientation) or physiologic (type of sexual reproduction) characteristics. Other approaches have used multiple features (many of those listed above), but with informal argumentation (rather than formal analysis) about their importance in the development of the classification scheme. Formal analyses of molecular, morphological and / or both data types have become more common recently, providing insights into the phylogenetic relationships of diatoms. Some of these analyses support aspects of more traditional classifications, but many suggest the data are in direct conflict with many of the taxonomic groups, or have not been recognized in the most recent classification for diatoms (now some 25 years old). Analyses of morphological data of fossil taxa provide new insights into evolutionary relationships of exclusively extinct taxa, with similar challenges related to current classification schemes. In this presentation, we review some of the history of classification systems for the diatoms and the concept of monophyly and its importance to creating natural groups. We highlight new data on the phylogenetic relationships of the major groups of diatoms, and show how these data are at odds with current classification schemes. We present a new classification system for the diatoms based on these phylogenetic relationships. Finally, we present examples of finer-grained relationships of fossil and extent taxa and the implications of these relationships for a classification. We suggest to achieve a natural classification for the diatoms will necessitate major changes in the groups recognized, also requiring new ways to educate students about the classification system of the diatoms. ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________

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EFFECTS OF URBAN CHEMICAL STRESSORS ON STREAM BIOFILMS Sylvia Lee1, Emma Rosi-Marshall1, Alexis Paspalof2, John Kelly3, and Sujay Kaushal4 1Cary Institute of Ecosystem Studies, Millbrook, New York, 12545 USA 2University of Nebraska-Lincoln, Lincoln, Nebraska, 68588 USA 3Loyola University Chicago, Chicago, Illinois, 60660 USA 4University of Maryland Baltimore County, Baltimore, Maryland, 21250 USA

Urban streams receiving wastewater contain contaminants including illicit drugs, pharmaceuticals, and road salt. Contaminants may have complex, sublethal consequences on ecosystem structure and function. Using three artificial stream experiments, we tested the effects of road salt, amphetamine, antihistamine (the active ingredient in Benadryl), and a cocktail of 8 pharmaceuticals on diatom and bacterial communities in stream biofilms. All contaminants suppressed gross primary production of biofilms. Only salt suppressed community respiration. To understand the mechanisms underlying changes in metabolism, we examined composition of biofilm communities exposed to contaminants using microscopic identification of diatoms and high-throughput sequencing of bacterial genes. While antihistamine did not affect bacterial respiration, there was a difference in bacterial community composition between antihistamine and control streams. The difference in bacterial composition was partly because of high abundances of a bacterium that is known to break down large, aromatic compounds. Salt was a strong driver of diatom community composition, but consistent differences were also found between diatoms in antihistamine and control streams. The context dependency of biofilm responses to urban chemical stressors will be discussed.

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MORPHOLOGY AND MOLECULAR STUDIES ON LARGE NEIDIUM SPECIES OF NORTH AMERICA, INCLUDING AN EXAMINATION OF EHRENBERG’S TYPES Keely E. Lefebvre1 and Paul B. Hamilton2 1Centre for Advanced Research in Environmental Genomics, University of Ottawa, Ottawa, Ontario K1N 6N5 Canada 2Research and Collections Division, Canadian Museum of Nature, Ottawa, Ontario K1P 6P4 Canada The diatom genus Neidium contains over 300 species of pennate diatoms found in brackish, freshwater environments with many of the larger taxa first described in the 1800s. There continues to be taxonomic confusion over several of the widely used species including N. dilatatum and N. amphigomphus. In this study large Neidium taxa (>50 µm) from North America were examined using both morphology and phylogenetics. Specimens from the original field collection housed in the Museum für Naturkunde were examined under LM and SEM. Single cells were isolated from samples collected in New York USA and Ontario CA and sequenced for rbcL and 18S. Maximum Likelihood and Bayesian phylogenetic analyses were completed and compared against current taxa descriptions. Our results confirmed several of the previously named Neidium taxa including: N. tumescens, N. hitchcockii, and N. amphigomphus. A new species was split from N. dilatatum and is formally described as N. fossum sp. nov. N. fossum is distinguished by its size, longitudinal canal structure, central area and proximal raphe ends. Combining morphological and phylogenetic methods will allow for further delineation of diatom taxa.

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WILL THE REAL NAVICULLA PERPUSILLA GRUN. PLEASE STAND UP? Rex L. Lowe1, Jennifer Ress2, and Jeff Johansen3 1Angelo Coast Range Reserve, 42101 Wilderness Lodge Road, Branscomb, CA 95417, 2Aims Community College, 5401 West 20th St., Greeley, CO 80634 3John Carroll University, University Heights, OH 44118 Navicula perpusilla was described by Grunow in 1860 and illustrated in Van Heurck. The illustrations are small and difficult to interpret. Navicula perpusilla has been reported from and illustrated in manuscripts and monographs both in print and on line from numerous locals, Wolnik & Carter 2014,Caraus 2002, Stoermer et al. 1999, Patrick and Reimer 1966). This taxon was transferred to the genus Diadesmis by Round et al. (1990) and later to Humidophila (Lowe et al. 2014) and continues to be illustrated from many florae. It was difficult to determine if our specimens collected from an extensive algal survey of the Great Smoky Mountains National Park fit the species concept of Humidophila perpusilla and upon examining Grunow’s type material of Navicula perpusilla we have concluded that the Great Smoky Mountains populations and perhaps other North American populations represent an undescribed species of Humidophila which will be described in a forthcoming publication.

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DIATOM COMMUNITY ATTRIBUTES IN ESTABLISHING NUTRIENT CRITERIA FOR GEORGIA STREAMS Kalina M. Manoylov1, Michele P. Brossett2, Cody Jones2, and Brad Konwick3 1Department of Biological and Environmental Sciences, Georgia College and State University, Milledgeville, Georgia 31061 USA 2Department of Natural Resources, Environmental Protection Division, Watershed Protection Branch, Atlanta, Georgia 30334 USA 3University of Georgia, Griffin, GA 30223 Algal biodiversity remains largely unknown and species composition is subject to a number of anthropogenic alterations to the aquatic environment. Georgia’s water quality criteria state that all waters shall protect human health, fish conservation, wildlife, and other beneficial aquatic life. Wadeable streams and rivers in the State of Georgia were sampled following standard protocols by Environmental Protection Division biologists. Diatom community composition and physicochemical characteristics at each site were assessed and compared. Stream collection sites were separated by class: 1-Least impacted, 2-Impacted, or 3-Highly impacted. Classes were based on both land use and the number of National Pollutant Discharge Elimination System permits in the watershed upstream of the sampling site. Water quality (conductivity, pH, total nitrogen (TN), and total phosphorus (TP) was evaluated for each site. Diatom community indices, Diatom Bioassessment Index (DBI), and diatom based Biological Criteria Gradient (BCG) for each streams were calculated and compared. Diatom species composition classifications were in agreement with water quality parameters. Achnanthidium minutissimum dominated more than 60% of the sites and had low TP optimum, but were able to tolerate higher TN concentrations. Presence of this taxon did not influence the DBI classification, but was important for the BCG classification. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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TRANSPARENT VS. OPAQUE SAND: VARIATION IN COMPOSITION AND ABUNDANCE OF INTERTIDAL EPIPSAMMIC DIATOM COMMUNITIES Shigeki Mayama1 and Hiroko Nakamura1

1Department of Biology, Tokyo Gakugei University, Koganei, Tokyo 184-8501, Japan Intertidal sands are usually composed of mineral granules and small rock chips in temperate zones. The main components of intertidal sand in Tokyo Bay are quartz, feldspar, pyroxene, olivine, amphibole and rock chips. The former two minerals are transparent and have smooth surfaces, whereas the other minerals are opaque with varying colors resulting from the inclusion of iron, magnesium and other elements. The surface of these grains are rougher than that of transparent sand. Rock chips are roughly classified into transparent and opaque depending on their mineral components. We examined the abundance and community composition of diatoms living on sand grains collected from Tokyo Bay. The study was performed in June and September. In both months, more diatom cells were observed on the surface of the transparent sand grains than that of the opaque grains with significant difference. Light permeability tested in a 1 mm thick sand layer in sea water was about 60 fold higher in the transparent grains than the opaque. Observed diatoms on the sand grain surfaces were classified into 3 types: species attaching to sand with the valve face (Type I: monoraphids and many naviculoids), species attaching with the valve face but showing girdle bands externally (Type II: amphoroids), species attaching with the girdle side (Type III: araphids and biraphids forming chain colony). Type III was more abundant in the transparent sand grains in both June and September collections. However, Type I was most abundant in the opaque grains in June. Moreover, the amount of Type I and Type III was almost equal in September. Sand characters, tidal disturbance and cell motility are discussed as growth factor of epipsammic diatom communities. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

  37  

INSIGHTS ON DIATOM EVOLUTION FROM FORTY DIATOM PLASTID GENOMES Mengjie AnnaYu1, Matt P Ashworth1, Edward C Theriot1, Jamal S Sabir2, and Robert K Jansen1,2

1 Department of Integrative Biology, University of Texas at Austin, Austin TX 78712, USA 2 Biological Sciences Department, Faculty of Science, King Abdulaziz University, Saudi Arabia Knowledge of genome architecture evolution and nucleotide substitution rates are essential for our understanding of the tempo and mode of molecular sequence evolution. So far, fifteen diatom plastid genomes have been published, and they show variable genome sizes and extensive genome rearrangements. Our recently published research added another seven diatom plastid genomes, revealing conserved gene order and expanded inverted repeats in plastid genomes of the order Thalassiosirales and documenting the first loss of photosynthetic genes in a photoautotrophic diatom (Rhizosolenia imbricata). Our 18 newly finished plastid genomes show extensive genome rearrangements with genome size ranging from 121,011bp to 201,816bp (the largest diatom plastid genome sequenced so far). We also found the loss of photosynthetic genes (psaE, psaI and psaM) in Rhizosolenia fallax, a closely related species to Rhizosolenia imbricata. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

  38  

‘ROBO-ECOLOGY’ & THE FOURTH PARADIGM: EMPOWERING HAB PREDICTIVE ANALYTICS & KNOWLEDGE DISCOVERY RELEVANT TO GREAT LAKES STEWARDSHIP

David F. Millie1 and Gary Weckman2

1Palm Island Enviro-Informatics LLC, Sarasota, FL 2Ohio University, Athens, OH

Data exploration – the curation, synthesis, and analysis of large, high-dimensional data volumes (such as those which arise from multi-year surveillance programs), has been denoted the fourth paradigm of scientific discovery. Empirical modeling of environmental influences upon phytoplankton typically has utilized parametric technologies; yet, such analytics often do not describe and (or) be appropriate for discerning the mosaic of interactive environmental conditions and species distribution patterns. Rather, analytics incorporating robust, even unconventional, approaches for data minimization, identifying data structures, and deriving user-friendly information are required. To this end, machine-learning algorithms capable of autonomously unearthing and reproducing complex patterns within sizeable data quantities afford great potential for fueling ecological hypothesis creation and ‘intelligent’ knowledge derivation (here, ‘Robo-ecology’).

As examples, phytoplankton were modeled with the intent to delineate phosphorus ‘thresholds’ for mitigating harmful algal blooms (HABs) within Saginaw Bay, Lake Huron and western Lake Erie. Models effectively characterized the intrinsic variance and magnitude of HAB biomass. Model-derived response surfaces then visualized HAB ‘niche space’ within the boundaries of environmental distributions and portrayed the non-linear uncertainties associated with prediction. Such an approach provided the predictive framework from which quantifiable knowledge concerning environmental–phytoplankton associations can be derived and is presented as a heuristic instrument relevant to decision making within natural resource stewardship.

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  39  

COMPARISONS OF MORPHOLOGICAL CHARACTERS IN THE ORGANIC LAYERS UNDERLINING SILICIFIED CELL WALLS OF DIATOMS. Noriaki Nakamura1, Matthew Julius2, Yoshiaki Maeda3, Tsuyoshi Tanaka3, Koichiro Fujimoto4 and Shigeki Mayama1 1 Department of Biology, Tokyo Gakugei University, Japan 2 Department of Biology, St. Cloud State University, USA 3 Institute of Engineering, Tokyo university of Agriculture and Technology, Japan

4 Department of Environmental Science, Tokyo Gakugei University, Japan Organic layers underlining diatom’s silicified frustule have been reported in sectioned cells of many diatoms. But, there are few reports about the complete structure of organic layers and their functions still remain unclear issues. In this study we observed organic layers in whole view from more than 20 diatom species and compared their structure with each specimen’s overlapping silicified cell wall. Many organic layers were bag-like structures facing the entire theca and some were non bag-like structures underlining silicified theca partially. In TEM observation of non stained specimens, bag-like organic layers showed three types of high electron density patterns: patterns corresponding to each areolae (group 1), corresponding to each striae (group 2) and lacking patterns (group 3). AFM observation showed that these patterns corresponding to areolae were thicker than other portions of the organic layers. Areas corresponding to the sutures pars interior showed high electron density lines. Portions of organic layers under occelli or rimoportulae had single or multiple small pores. In EDX analysis, nitrogen and sulfur were detected as components of organic layers along with elements of carbohydrate in Pseudoleyanella lunata. Functions of organic layers are discussed including increased protection ability to withstand external pressure, maintenance of intracellular moisture, prevention of enemy invasion, and provision of a matrix for developing vela. _________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ________________________________________________________________________

  40  

TWO CENTURIES OF VARIATIONS IN DIATOMS AND ELEMENTAL GEOCHEMISTRY FROM LAGO LUNGO, RIETI BASIN, LAZIO, ITALY.

Paula J. Noble1, Irene Tunno2, Scott Mensing2, and Gianluca Piovesan3

1 Department of Geological Science and Engineering, University of Nevada, Reno NV 89557 USA 2 Department of Geography, University of Nevada, Reno NV 89557 USA 3 Dendrology Lab, DAFNE, Università degli Studi della Tuscia, Viterbo, 01100 Italy

We present preliminary diatom counts and elemental geochemistry in a core from Lago Lungo, dating to ~1830 CE, that show major changes in water quality and hydrologic inflow largely attributed to reclamation and land use activities. Lago Lungo is a shallow (~4.5m), small (~0.8km2 surface area), eutrophic, hard water lake situated in an intermontaine alluvial plain, ~90 km NE of Rome. It is one of several remnant lakes in a poorly drained wetland area fed by numerous springs and seeps. Considerable reclamation activities over the last century, and even dating back to Roman times, have substantially altered the drainage network affecting water delivery to the lakes and their connectivity. There are 3 interesting signals. Small Stephanodiscus species, associated with hypereutrophic conditions, first appear after 1950 and peak ~1990. This trend may be associated initially with increased use of chemical fertilizers and intensification of local agriculture. A decline in Stephanodicsus after 1990 reflects some improvement to the water quality following the lake’s incorporation into a nature preserve and creation of a narrow vegetation buffer. A large change in the core stratigraphy, elemental geochemistry, and diatom composition occurs ~1940 and is associated with several major reclamation efforts, including the rerouting of the Santa Susanna channel, which redirected large volumes of artesian inflows away from the lakes and estuarine system. Upstream, dams on the Turano and Salto rivers were also constructed, further affecting hydrological inflows into the basin. From ~1900-1940 there is an abundance in Aulacoseira granulata, a species that dominates the adjacent Lago di Ripasottile. The largest compositional change occurs ~1900, where before Cyclotella distinguenda is an abundant phytoplankton component and periphyton is a considerably larger component of the flora. Prior to ~1900, the lake may have received additional hydrological inputs, including drainage from larger marsh areas that were diverted after 1900.

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  41  

FRACTIONATED CHLOROPHYLL A DYNAMICS OF SOUTHERN LAKE MICHIGAN

Kristy Phillips1, Emon Butts1, and Hunter Carrick1

1Department of Biology, Institute for Great Lakes Research, Central Michigan University, Mount Pleasant, MI 48858

There have been several large-scale changes to the production and function of Lake Michigan that coincide with the introduction of dreissenid mussels. The deep chlorophyll layer (DCL) was historically fueled by the early spring algal bloom that was dominated by mesophillic diatoms that seem to no longer be present in Lake Michigan as they were during pre-dreissenid introductions. Samples were collected to act as a surrogate for biomass across three size fractions (picoplankton <2µm, nanoplankton 2 to 20 µm and microplankton >20µm). Spatial and vertical profiles of size fractionated chlorophyll were collected in 2013, 2014 and 2015. Four transects were sampled in the southern Lake Michigan basin (Racine, St. Joseph, Saugatuck and Muskegon) at various distances from the shore (nearshore and offshore) and at various depths (epilimnion, DCL and two meters from the bottom) in order to achieve a spatial and vertical chlorophyll profile. The first question that was investigated was if the size fractions and their relative proportion at the Muskegon transect in the DCL from 2013 and 2015 was different. The picoplankton in 2013 had a mean concentration of 0.74 µg/L (18%) where it was 0.95 µg/L (65%) in 2015 with no significant difference between the two years at the Muskegon transect (p=0.395). Phototrophic nanoplankton and microplankton greatly differed from 2013 to 2015 at the Muskegon transect during stratification (p=0.003 and p=0.000, respectfully). There was a mean of 1.52 µg/L (38%) nanoplankton and 1.77 µg/L (44%) of microplankton and in 2013 where there was 0.34 µg/L nanoplankton and no detectable microplankton in 2015. Nanoplankton and microplankton may have been due to the 100-year flood in 2013 and the influx of runoff from the Grand River and Muskegon Lake. The second question that was investigated was if the three size fractions were influenced by season (Spring versus summer), station (nearshore versus offshore) and by transect in 2015. The Muskegon plankton assemblage across all size fractions were significantly different from the other 3 transects in southern Lake Michigan (p<0.005). The western transect ‘Racine’ was significantly different than the southeastern transect ‘St. Joseph’ in the nanoplankton assemblage (p=0.008). There was no difference between the other transects (season and station). These results suggest that regions of the southern Lake Michigan basin are different and the size fractions may be influenced by other factors such as run-off or lack of nutrients.

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  42  

CAN VARIATION IN THE VALVE MORPHOLOGY OF DIDYMOSPHENIA GEMINATA TELL US ANYTHING ABOUT ITS RECENT HISTORY? Robert W. Pillsbury1, Cathy Kilroy2, Mark B. Edlund3, and Brenna Glas 1

1Department of Biology, University of Wisconsin Oshkosh, Oshkosh, WI 54901 USA 2National Institute of water and Atmospheric Research Ltd, Christchurch, New Zealand 3St Croix Watershed Research Station, Marine on St. Croix, MN 55047 USA Within the past two decades Didymosphenia geminata seemingly spread broadly to produce nuisance blooms in mainly oligotrophic rivers. But why is this expansion occurring now? One hypothesis is that an aggressive strain of D. geminata has mutated/developed. Another hypothesis is that D. geminata was present although rare in most habitats but recent environmental changes have made these blooms more likely to occur. We examine the variation of valve morphology found both within and among populations of D. geminata collected from North America and New Zealand by using both direct measurements and Landmark Analysis. We then compare patterns in variation found to those predicted from each hypothesis. We found that Morphological patterns among North American populations are consistent with those predicted by the Environmental Change hypothesis while New Zealand populations seem consistent with the Aggressive Strain hypothesis. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

  43  

TRACKING EUTROPHICATION OF NEW JERSEY COASTAL LAGOONS WITH DIATOMS

Marina Potapova1,2, Nina Desianti2, Mihaela Enache3, and Thomas Belton3

1Academy of Natural Sciences of Drexel University, Philadelphia, PA 19103, USA, 2Department of Biodiversity, Earth and Environmental Sciences, Drexel University, Philadelphia, PA 19104, USA 3New Jersey Department of Environmental Protection, Trenton, NJ 08625, USA

The 400-year history of diatom assemblages of the New Jersey coastal marshes was studied using five dated sediment cores. The common trend in the composition of the assemblages was the shift from the relatively large-celled coastal diatoms, such as Cosmioneis pusilla, Navicula peregrina, Frustulia creuzburgensis, Diploneis spp. and Caloneis spp. towards small-celled Cyclotella, Navicula, Nitzschia and Amphora species. This shift was pronounced in the Barnegat Bay that has been experiencing considerable nutrient pollution and less evident in the relatively clean Great Bay. The inference models developed from a calibration dataset of 100 modern samples were applied to the core data. The models indicated that the shift was associated with a considerable increase in sediment carbon and nitrogen in the course of the last 150 years. Diatoms-inferred increase in salinity over the time corresponds to the sea level rise well documented for the mid-Atlantic coast of North America. We also investigated temporal trends in diatom assemblages of the subtidal habitats using another set of 100 sediment samples collected from 50 sites in New Jersey coastal lagoons and estuaries. The short “cores” were not dated, but we identified and enumerated diatoms in the top and bottom samples from each site. We found a significant temporal trend in diatom assemblage composition towards the dominance of extremely small planktonic diatoms and decline of benthic diatoms in the “top” samples. Although the exact mechanism of this community change cannot yet be established, the bulk of evidence from the other studies on coastal habitats suggests the eutrophication might be the most important cause.

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  44  

THE RISE OF CYCLOTELLA IN 90 % OF NORTH AMERICA’S SURFACE WATER Euan D. Reavie1, Gerald V. Sgro2, Lisa R. Estepp1, Andrew J. Bramburger1, Victoria L. Shaw Chraïbi3, Robert W. Pillsbury4, and Craig A. Stow5 1Natural Resources Research Institute, University of Minnesota Duluth, Duluth, MN 55811 USA

2John Carroll University, University Heights, OH 44118 USA 3University of Nebraska-Lincoln, Lincoln, NE 68588 USA 4University of Wisconsin Oshkosh, Oshkosh, WI 54901 USA 5NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, MI 48105 USA The Laurentian Great Lakes represent most of the fresh surface water on the continent. Monitoring of the Great Lakes microflora has revealed changes in whole-lake conditions in each of the lakes. Trends indicate impacts from invasive species and nutrients, and many impacts are revealed in a longer-term context in paleolimnology studies. Sedimentary analyses have further revealed changes in phytoplankton apparently driven by climate change. It was first recognized that rapid warming of Lake Superior has resulted in a complete reorganization of the algal community. The increase in the diatom Cyclotella in sedimentary profiles is obvious in recent decades, as has been recognized in lakes worldwide. Similar changes are now being observed in sedimentary profiles from Lakes Ontario, Erie, Michigan and Huron, despite the fact these lakes are notoriously influenced by other stressors including nutrients and invasive species. Not surprisingly, those responsible for tracking and maintaining ecosystem services on the Great Lakes are concerned about the ecological trajectories of the lakes. As a significant freshwater resource, it is worth considering the implications of this ongoing change at the base of the food web. Future concerns and areas of study will be discussed. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

  45  

POLYPHOSPHATE MAY PLAY A KEY ROLE IN THE PHOSPHORUS DYNAMICS OF DIATOM-DOMINATED PERIPHYTON IN OLIGOTROPHIC STREAMS Steven T. Rier1*, Keith C. Kinek1, Sarah E. Hay1, and Steven N. Francoeur2

1 Department of Biological & Allied Health Sciences, Bloomsburg University, 400 East 2nd Street, Bloomsburg, PA 17815, USA 2 Department of Biology, Center for Aquatic Ecology, Eastern Michigan University, Ypsilanti, MI 48197, USA There has been considerable resent interest in the role of polyphosphate (polyP) in marine biogeochemical cycles, yet there is also a high likelihood that polyP plays a critical role in the phosphorus (P) dynamics of stream periphyton. We monitored the effects of P pulses during natural storm events in a single stream, manipulated P pulses in stream mesocosms and sampled 23 streams at base flow across a landscape P gradient in order to ascertain patterns in polyP formation in stream periphyton. We found that P-pulses associated with natural storm runoff could elicit an overplus accumulation of polyP in stream periphyton, that periphyton are capable utilizing P delivered in a single pulse for future growth and biomass accumulation even when additional P was not available in the water column and that polyP can accumulate relative to biomass and P-pool in stream periphyton that have not been exposed to a recent pulse. It is possible that polyP formation under P-stressed conditions might represent a reallocation of resources in order to maximize the overplus response of algae and other microorganisms to future P pulses. Overall, polyP may serve as an important P retention mechanism for extremely oligotrophic stream ecosystems. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

  46  

AUTOTROPHIC AND HETEROTROPHIC MICROBIAL RESPONSES TO PHOSPHORUS ENRICHMENT IN THE FLORIDA EVERGLADES

Nick O. Schulte1 and Evelyn E. Gaiser1

1Department of Biological Sciences, Florida International University, Miami, FL

Benthic microbial communities can be dominant drivers of carbon turnover and regulators of biogeochemistry and ecosystem function in aquatic systems. This regulatory role of benthic microbial communities is determined by the metabolic dynamics of the dominant biological components, including photoautotrophs, heterotrophic bacteria and fungi, and their interactions with extracellular polymeric substances (EPS) and detritus. In shallow oligotrophic ecosystems such as the Florida Everglades, benthic microbial communities dominated by cyanobacteria and diatoms can produce thick mats that have been shown to dissociate when exposed to above-ambient levels of phosphorus. Oligotrophic freshwater marshes in the Everglades are dominated by few diatom taxa (Brachysira microcephala, Encyonema evergladianum, Fragilaria synegrotesca, and Mastogloia calcarea), well-studied, and used as water quality indicators in national monitoring programs. However, oligohaline diatom taxa and diversity are less understood, as are the interactions of diatoms from both regions with the other functional components of the mats with and without nutrient enrichment. How changes in nutrient supplies associated with global climate change and anthropogenic inputs influence the integrity, function, and biological interactions of microbial mats in shallow aquatic environments is a key uncertainty, especially in oligotrophic coastal wetlands where marine sources of nutrients are increasing with sea level rise. We manipulated phosphorus exposure to freshwater and oligohaline mats and measured metabolic, compositional, and structural responses to determine the community responses of benthic microbial mats to nutrient enrichment. We monitored changes in mat dry weight; organic and nutrient content; heterotrophic bacteria density; ergosterol content (fungal proxy); EPS mass; and diatom and soft algae composition. We present here preliminary data that contribute to the resolution of questions about how benthic microbial mat function, structure, and biological interactions will be influenced by increases in phosphorus in the Everglades. This research can be more broadly applied to better understanding microbial, particularly diatom, community response to nutrient enrichment in other shallow aquatic systems.

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  47  

A BENTHIC DIATOM METRIC FOR NEARSHORE LAKE ERIE Gerald V. Sgro1 and Euan D. Reavie2

1John Carroll University, University Heights, OH 44118 USA 2Natural Resources Research Institute, University of Minnesota Duluth, Duluth, MN 55811 USA

Toledo, Ohio shut off its water supply to 500,000 customers for two days in August 2014 because the city’s water treatment plant was overwhelmed by mycrocystin toxin from Lake Erie. The Ohio Environmental Protection Agency (OEPA) has a severe need to develop a water quality monitoring program for the Lake Erie nearshore that includes a biological component. A benthic diatom metric based on weighted average TP coefficients from a Great Lakes training set was tested in a pilot project by the OEPA by sampling 71 lacustrine and bay sites in nearshore Lake Erie in 2011 and 2012. The metric could significantly detect changes in the diatom community as affected by TP concentrations over five water quality categories, yet some results appear to be inconclusive. Should this metric be selected by the OEPA it may become the first use of diatoms by a government agency in a regular monitoring program for evaluating conditions in the Great Lakes. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

  48  

ALGAE AND NATIONAL BIOASSESSMENTS IN STREAMS, LAKES, WETLANDS AND COASTAL ZONES OF THE UNITED STATES: SUCCESSES AND CHALLENGES

R. Jan Stevenson1, Tang Tao1,2, and Bo Liu1

1Department of Integrative Biology, Michigan State University, 203 Natural Sciences Bldg. East Lansing, MI 48824, USA 2Chinese Academy of Sciences, Institute of Hydrobiology, Wuhan, China

Algae, and particularly diatoms, are being sampled in national assessments of ecological condition in four separate habitat types in the US, streams, lakes, wetlands and coastal zones. In at least two situations, inconsistency in taxonomy is severely limiting use of the algal indicators in assessments. Other challenges that exist include accounting for natural variation among reference sites and variation in quality of reference sites among regions. A series of methods are being developed and tested for consideration in future surveys. The traditional multimetric index (MMI) approach accounts for variation among sites using ecoregions, and is the most accepted approach. Modelled MMI approaches account for natural variation among individual sites within ecoregions by developing continuous regression models of expected reference (minimally disturbed) condition at a site with natural hydrogeomorphic and climatic characteristics of habitats and their watersheds as independent variables. Modelled MMIs then assess condition based on the deviation from expected reference: i.e. the difference between the MMI observed at a site (based on samples collected at a site) and the modelled expected reference MMI for that site. Considerable evidence suggests that a modelled MMI better accounts for natural variation than ecoregion-scale reference methods. Models for MMIs have been developed using natural variation among reference sites and therefore limit applicability to situations in which a large number of reference sites exist. A solution to this problem is to use all sites to develop models for expected reference condition, and predict minimally disturbed MMI and metric values using land use indicators of human disturbance as well as the hydrogeomorphic and climatic variables in a region. Expected reference condition for a site is then calculated as modelled values when land use is zero, or another relatively low level; then condition is again assessed as deviation from minimally disturbed condition based on the difference between the MMI observed at a site and the modelled expected reference MMI for that site. Incorporating land use into models of minimally disturbed condition also enables correcting MMIs for differences in quality of reference sites among regions. Adoption of new methods will require considerable research to demonstrate their transferability among ecosystems and even different kinds of organisms. Adoption will also require new methods to be more accurate, i.e. correctly identifying which sites are good or poor, or have greater separation between minimally and highly disturbed condition.

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  49  

SHIP HULL TRANSPORT OF MARINE DIATOMS THROUGH FRESHWATER Holly L. Sweat1, Geoffrey W. Swain1, and Kevin B. Johnson1

1Department of Marine and Environmental Systems, Florida Institute of Technology Melbourne, Florida 32901 USA Diatoms are a dominant component of marine biofilms that form on nearly all submerged surfaces. Diatoms adhering to ship hulls may be carried thousands of miles, where they can become invasive themselves or facilitate invasions of larger macrofouling species by encouraging larval settlement. Freshwater shipping routes are less effective than previously thought at killing macrofoulers travelling between oceans. However, no studies to date have examined how freshwater transport affects the mortality of marine biofilm organisms such as diatoms. Survivorship and transport of diatoms were investigated as marine biofilms traveled through Florida’s Okeechobee Waterway on three modern ship hull coatings: a copper antifouling paint, a silicone fouling-release coating, and an inert epoxy basecoat. Biofilms cultivated on both the Gulf of Mexico and Atlantic coasts of Florida were relocated, over 12 hours through >165 km of freshwater, to the opposite coast on the hull of a specially designed test vessel. Total diatom density and community composition varied among coating types. However, all coatings contained diatoms that survived the journey. Resilient diatoms included species from several genera, including Amphora, Cocconeis, Melosira, Navicula, and Nitzschia. These results provide further evidence of global biofilm transport and marine bioinvasions through shipping.

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  50  

POLYPHOSPHATE ACCUMULATION BY BENTHIC BIOFILMS IN PENNSYLVANIA STREAMS

Shayna M. Taylor1, John M. Regan2, Nicholas Locke2, Sheila Saia3, Todd Walters3, Anthony R. Buda4, and Hunter J. Carrick1.

1Department of Biology, Central Michigan University, Mount Pleasant, Michigan 48859 USA 2Department of Civil and Environmental Engineering, Penn State University, University Park, Pennsylvania 16802 USA 3Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York 14853 USA 4USDA-ARS Pasture Systems and Watershed Management Research Unit, University Park, Pennsylvania 16802 USA

Nutrient loading has contributed to eutrophication in rivers and downstream systems throughout the mid-Atlantic region, USA. It is known that biofilms can be assessed to determine the amount of phosphorus (P) pollution in a system and the agricultural impacts it has on stream health. Polyphosphates are a storage system in algal cells and can be used to reflect the degree of nutrient loading to stream ecosystems. An ISES (in situ enrichment system) experiment was deployed in four flumes of a USDA maintained stream watershed for a 12-day period. In July-August of 2014, experimental vials of agar were enriched with six levels of P loading from 0.0 to 1,540.8 µg PO4-3/day under consistently N enriched conditions. At the end of this period natural growing biofilms were scraped off tiles established in each site and analyzed for chlorophyll, total P, and polyphosphate. While there were no significant differences found in biomass growth between each treatment (two-way ANOVA; F= 3.387, p>0.042), there were significant increases in P storage with increased P provided (F= 148.853, p<0.001). We measured consistent uptake patterns throughout the watershed, suggesting that uptake was a consistent feature of biofilms throughout the landscape (F= 4.172, p>0.05). A large percentage of total P was also stored as polyphosphate in the treatments with added P in relation to the ambient tiles collected. In addition to the experiments we also tested both water column and benthic variables for TP, TN, chlorophyll, and polyphosphate for 20 streams throughout the state. While there was no correlation between water column nutrients and polyphosphate, there was a significant correlation between benthic chlorophyll (R2= 0.0285, p≤ 0.001) and benthic TP (R2=0.668, p≤ 0.001) and polyphosphate. Given these findings, we propose that polyphosphate storage in stream biofilms are an important, early warning indicator for changing trophic status in streams compared with biomass metrics (e.g., chlorophyll); therefore, P storage in stream algae reflects loading from throughout the terrestrial landscape. In addition, as the quantity of P in biofilms was large relative to P in the water column, we suggest that biofilms are an important sink in these streams. ________________________________________________________________________________________________________________________________________________________________________________________________________________________

  51  

WHERE BARCODES FEAR TO TREAD: THE MODERN STEPHANODISCUS FLORA IS A RESULT OF A SERIES OF RECENT AND RAPID RADIATIONS

Edward C. Theriot1*, Matthew Ashworth2, Mariska Brady2, Leslie Goertzen3, and Teofil Nakov2,4 1Texas Memorial Museum, 2400 Trinity Street, University of Texas, Austin, TX 78705, USA 2 Plant Biology Graduate Program, University of Texas at Austin, 1 University Station (A6700), Austin, TX 78712 3 Department of Biological Sciences, 101 Rouse Life Science Building, Auburn University, AL 36849 4 Department of Biological Sciences, 850 W. Dickson Street, University of Arkansas, Fayetteville, AR 72701, USA The prevailing paradigm in protistan ecology is that many protist species are cryptic, distinguishable by genetic sequences but indistinguishable morphologically. We examine 5 proposed barcode regions in freshwater Thalassiosiraceae with a highly resolved fossil record, a highly resolved molecular phylogeny and fine-grained morphometric analyses. The first major finding was that barcode genes consistently underestimate diversity. The second major finding was the low resolution is likely due to numerous rapid radiations of freshwater Thalassiosiraceae in the late Pleistocene and early Holocene. Clades which generally inhabit geologically ephemeral habitats (e.g., north temperate lakes) may be more prone to extinction and re-radiation events than clade which inhabit more geologically permanent habitats (e.g., rivers and estuarine environments). ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

  52  

A DIATOM-BASED HOLOCENE HISTORY OF THE ÅNGERMANÄLVEN ESTUARY, IODP EXPEDITION 347 – BALTIC SEA PALEOENVIRONMENTS Jonathan P. Warnock1

1Department of Geoscience, Indiana University of Pennsylvania, Indiana, PA 15701 The Baltic Sea has experienced a complex climatological and ecological history during the Holocene, due to the deglaciation of Scandinavia and the complex morphology of the basin. Human habitation over the last several centuries has also affected the ecology of the Baltic, especially in coastal regions. While the history of the Baltic has been studied in the past, a comprehensive coring mission linking changes across the basin had not previously been undertaken. One of the primary goals of Expedition 347 was to capture Holocene records from across the basin in order to generate a comprehensive chronology of changes to nutrients, salinity, and primary productivity. This study focuses on two cores recovered from the Ångermanälven Estuary, Sweden. Utilizing established diatom ecologies and absolute diatom abundances, shifts in salinity, nutrients, and river discharge into the basin have been established. Additionally, the increasing influence of human development of Scandinavia is detected. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

  53  

GROWTH AND BIOCHEMICAL RESPONSES OF SKELETONEMA COSTATUM TO PETROLEUM CONTAMINATION James L. Wee1, David F. Millie2, Ngan K. Nguyen1, Johnathan Patterson3, Rose Ann Cattolico3, David E. John4, and John H. Paul4 1 Department of Biological Sciences, Loyola University New Orleans, New Orleans LA 2 Palm Island Enviro-Informatics, LLC, Sarasota, FL 3 Department of Biological Sciences, University of Washington, Seattle WA 4 College of Marine Science, University of South Florida, St. Petersburg FL A strain of Skeletonema costatum isolated from Lake Pontchartrain (Louisiana USA) located nearby the Deepwater Horizon oil release into the Gulf Of Mexico was exposed to light slop crude oil. Experimental laboratory populations exposed to uncontaminated f/2 media utilizing Lake Pontchartrain water and oil-emulsified (O-E) f/2 media (25, 50, 75, and 100% of initial levels) were evaluated during short- and long-term incubations. During 10-day incubations, inhibition of logarithmic growth slopes occurred in the most severely contaminated populations (75 and 100% O-E f/2). Growth curves for oil-contaminated populations were diminished during 21-day incubations, with growth rates for all populations converging by ca. day 12. Relative abundances of cellular fatty acids and RNA transcript copy numbers for RuBisCO, proxies for commitment to food storage and photosynthetic activity, respectively, were altered half-way through the long-term incubation; C16:0 and C16:1 fatty acids were greater and less, respectively, and RNA transcript copy numbers were greater within severely contaminated populations. Yet, fatty acid abundances and RuBisCO copy numbers were equivalent among culture populations by the end of the incubation. Oil contaminants within the culture medium were measured, with the presence of C6-C12 hydrocarbons and arsenic coinciding with initial growth inhibition and later altered cell physiologies, respectively. From this, relationships among cell growth, food reserves, and photosynthetic potentials were deemed useful determinants for assessing phytoplankton inhibition in response to petroleum contamination. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

  54  

URBAN LAKE ASSESSMENT: WATER QUALITY AND LAKE CONDITION IN CUYAHOGA COUNTY, OHIO

Julie A. Wolin1, Megan Dunleavy1, Tom Bienvenu1, Justin Ostry1, and Amelia Visnauskas1

1Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, Ohio 44115 USA

To better understand the functional role of water bodies in urban and suburban regions, we conducted a county-wide assessment of lakes, reservoirs, and retention ponds in Cuyahoga County, OH in 2013. Physical characteristics, surrounding land use, waterfowl presence, shoreline vegetation, water chemistry, microcystin, and surface sediments for diatom analysis were sampled at forty sites following protocols developed for the 2012 US National Lake Assessment (NLA) and the Ohio EPA Inland Lake Water Quality Monitoring Program. Surveys were conducted to determine lake management practices i.e. fertilizer use, dredging, and method of algal control. Grass was the dominant shoreline vegetation. Our results indicate 40-50% of the sample sites had poor shoreline habitat, comparable to 41% of man-made lakes found in the 2007 NLA. Visual algal assessment indicated moderate to extensive algae in 34% and detectable algae in 57% of the lakes. Microcystis was visible at 50% of the sites, while microcystin concentrations above WHO drinking water guidelines (1ug/l) were only found in three lakes. Surface sediment diatom community analysis indicate dominant factors contributing to lake condition are nutrient gradients and depth.

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FRESHWATER TURTLES AND THEIR EPIZOOIC DIATOM ASSEMBLAGES

Shelly Wu1 and Elizabeth A. Bergey1 1Department of Biology and Oklahoma Biological Survey, University of Oklahoma, Norman, OK 73019 USA

The shells of freshwater turtles provide a substrate for epibionts including algae. Unlike most other substrates, turtles move, bask, and excrete – behaviors that affect exposure of diatoms to desiccation, light regime, abrasion, and nutrients. Diatom assemblages were compared among five turtle species in Oklahoma and throughout a larger portion of the range for the common snapping turtle, using specimens from two museums. Temporal variation of diatom assemblages was investigated using red-eared sliders from Lake Texoma, OK, turtles collected in the 1950s and recently collected turtles. Turtle species had different diatom assemblages, although Luticola goeppertiana was commonly found. Diatom assemblages on the common snapping turtle varied regionally. A comparison of diatom assemblages from Lake Texoma shows that recent assemblages had a higher abundance of Epithemia adnata. Results indicate that the diatom-turtle relationship is a good model to study freshwater epibiosis.

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Poster Presentation Abstracts

The NADS Program 2015: Central Michigan University Biological Station

THE ECOLOGICAL HISTORY OF LAKE ONTARIO ACCORDING TO PHYTOPLANKTON

Lisa R. Allinger1 and Euan D. Reavie1 1Natural Resources Research Institute, University of Minnesota Duluth, 5013 Miller Trunk Highway, Duluth, Minnesota, 55811.

Lake Ontario’s water quality has fluctuated since European settlement and our understanding of the cause-and-effect linkages between observed ecosystem shifts and stressors is evolving and improving. Changes in the physical and chemical environment of the lake due to non-indigenous species, pollution, sedimentation, turbidity, and climate change altered the pelagic primary producers, so algal assessments have been valuable for tracking long-term conditions. Paleolimnological and long-term monitoring studies, particularly those using diatoms, reveal long-term changes, providing a rich understanding of multiple stressor effects on primary production including climate-driven change. We used an analysis of sedimented diatoms from Lake Ontario to summarize pre-European settlement, eutrophication throughout most of the 20th century, and subsequent nutrient reductions. Since the 1980s increases in several species from the genus Cyclotella, and a decrease in Aulacoseira islandica suggest lower nutrients, but nutrients alone do not appear to be the major determinants of higher Cyclotella abundance. In Lake Ontario there is a clear correlation with recent increases in atmospheric and water temperatures and longer ice-free periods, a trend that has repeated throughout the Great Lakes basin. Recent monitoring data suggest that although phytoplankton biovolume remains stable, species composition is reorganizing. We are currently applying a diatom-based indicator approach that combines modern and paleolimnological data to address issues requiring long-term data for water quality management and remedial decisions ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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MICROPHYTOBENTHOS DIVERSITY FROM MUDFLATS ALONG THE SAVANNAH RIVER ESTUARY Jelena Andrejic1,2, Ellen France1, and Kalina M. Manoylov1 1Department of Biological and Environmental Sciences, Georgia College and State University, Milledgeville, Georgia 31061 USA 2Nuclear Sciences "Vinca", Laboratory for Material Sciences, 11000 Belgrade, SERBIA Estuaries are known to have a diverse combination of freshwater, marine, and brackish organisms. The microphytobenthos is composed of photosynthetic eukaryotes and cyanobacteria with largely unknown life history and composition. Samples from the Savannah River mudflats were collected at low and high tide, 23 kilometers from the Savannah port at a USGS monitoring site. An attempt to culture taxa from the community was performed for all algae, with the goal of developing a molecular and morphologic catalogue for each taxon. In addition, cleaned diatoms were analyzed following standard methods. Scanning and light microscope data were analyzed, and morphometric measurements for each taxon were collected. 320 algal species were documented and are currently in different stages of description, culture development or sequencing. The algal community is dominated by planktonic marine diatoms like Cymatoseira belgica and freshwater riverine diatoms from the genera Navicula, Luticola, and Cyclotella. Many new taxa described were marine or brackish. The results from this research will serve as a baseline for changes in the community composition of primary producers from the Savanna river mudflats after the deepening of the Savannah Port. ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________

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SEMIORBIS IN THE UNITED STATES Andresen, N.A.1, Edlund, M.B.2, and Burge, D.R.L.2

1Andresen Consulting LLC, 5742 Princeton Pl., Ypsilanti, MI 48197 2St. Croix Watershed Research Station, Science Museum of Minnesota, Marine on St. Croix, Minnesota 55423 USA The genus Semiorbis was erected by Patrick in 1966 as monotypic based on the relatively rare taxon Semiorbis hemicyclus. Although once considered an araphid taxon, scanning electron microscopy showed that Semiorbis hemicyclus had short subterminal raphe branches on the valve mantle that clearly placed the genus within the Eunotiales with additional defining characters of strongly arcuate valves, well developed external costae with spine-like projections on the interstriae, lack of rimoportulae, and a broader dorsal mantle. Recent work by Reid and Williams (2010; Diatom Research 25:355) recognized two additional taxa within Semiorbis including a new species from the eastern United States, Canada, and Japan called Semiorbis rotundus, and a species transferred from Eunotia, Semiorbis catillifera, that was earlier described from Alabama. The generitype, Semiorbis hemicyclus, was suggested to be limited in distribution to northwest Europe and Greenland. A population of Semiorbis was found in the central US on Outer Island, Apostle Islands National Lakeshore, along southeast Lake Superior. The population was in Outer Lagoon, a shallow embayment cut off from Lake Superior by a longshore bar. We provide the first documentation of living cells and colonies of Semiorbis, consider the taxonomy of this population using light and scanning electron microscopy, and examine historical population dynamics of Semiorbis with dated sediment cores from the lagoon. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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PHYSIOLOGY AND DESCRIPTION OF ABNORMAL LIVE AND DEAD DIATOMS FROM AGRICULTURALLY IMPACTED STREAMS IN OHIO Laura L. Aycock1, Nathan Smucker2, Morgan L. Vis3, and Kalina M. Manoylov1 1Department of Biological and Environmental Sciences, Georgia College and State University, Milledgeville, Georgia 31061 USA 2 Oak Ridge Institute for Science and Education Fellow c/o U.S. Environmental Protection Agency, Atlantic Ecology Division, Narragansett, RI 02882 USA 3 Department of Environmental and Plant Biology, Ohio University, Athens, Ohio 45701 USA Samples collected from the Western Allegheny Plateau of southeast Ohio were analyzed for whole algal community composition. For this project, only sites with documented agricultural impact were analyzed in detail. Physiology of diatoms preserved at the time of collection was studied years after collection. Diatoms were classified as live if chloroplast or other organelles were present. Diatoms exposed potentially to pesticides, fertilizers and other growth enhancement products might be expected to have deformities in the frustule, but morphometric and physiology of those diatom populations have not been previously analyzed. There are several types of diatom frustule deformities. The most common type of deformities seen was where the frustule is bent or incised. This abnormality is potentially caused by external and mechanical mechanisms during frustule biogenesis. Deformities in diatom frustules were documented and related to season, land use and presence of other algal groups. Deformities were present in Achnanthidium minutissimum (Kützing) Czarnecki and Fragilaria tenera (Smith) Lange-Bertalot. In spring collections, 72% of the Gomphonema parvulum (Kützing) Kützing had bent frustules or striae pattern deformities. This research is one of the first to study in detail the life history and physiology of deformed diatoms along a gradient of exposure to agricultural products. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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THOSE BELOW DAM DIATOMS Elizabeth A. Bergey1, Nina Desianti1,2, and Joshua T. Cooper1

1Oklahoma Biological Survey, University of Oklahoma, Norman, Oklahoma 73019 USA 2The Academy of Natural Sciences of Drexel University, Philadelphia, PA 19103, USA Bottom-release dams can result in downstream novel ecosystems through the alteration of flow regime and water temperature. We sampled rock-dwelling diatoms at nine sites for six samplings and at one site for 27 samplings (14 months) in the Lower Mountain Fork downstream of Broken Bow Lake dam in southeastern Oklahoma. The presence of Didymosphenia geminata well outside its projected range highlights the uniqueness of the river, which is colder and more oligotrophic than surrounding waters. We found 88 diatom species. None had distributions associated with Didymosphenia, which was found at only at the two sites located between the erosive tailwaters and the depositional area created by a small dam. Downstream and seasonal patterns of species occurrence were evident and diatom assemblages indicated low nutrient concentration. Because several diatom species were shared with the warmer river upstream of the reservoir and diatom composition indicated oligotrophy, we concluded that nutrient concentration affected diatom assemblages more than did water temperature. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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PHYTOPLANKTON SEASONALITY ACROSS A GRADIENT OF ISLAND LAKES AND LAKE MICHIGAN: IMPORTANCE OF WINTER PHYTO-FLAGELLATES Emon K. Butts1 and Hunter J. Carrick1

1Department of Biology & Institute for Great Lakes Research, Central Michigan University, Mt. Pleasant, MI 48859 USA. There is limited information about phytoplankton seasonality in temperate lakes, specifically during the winter months. In this study, data was collected over one year in order to document the seasonality in phytoplankton assemblages occurring in six lakes located on Beaver Island, Michigan and northern Lake Michigan (offshore Beaver Island). The biogeochemical conditions varied greatly among lakes, despite their close proximity to one another (<20 km apart) and similar, regional climate. Annual averages in pH ranged from 5.6 to 8.6 units, total phosphorus ranged from 10.6 to 19.8 µg/L, and chlorophyll concentrations spanned more than an order of magnitude (ranged from 0.8 to 31.1 µg/L). That said, lakes to the interior of the island were characterized by high concentrations of DOC and low conductivity and pH, while conversely, perimeter (coastal) lakes had low DOC concentrations, high conductivity, and high pH. In general, phytoplankton biomass and chlorophyll-a were greater in the interior lakes versus perimeter lakes (two-way ANOVA, F = 6.1, p = 0.018 and F = 6.9, p = 0.012, respectively). Total phytoplankton carbon varied significantly among the four seasons (F= 6.0, p = 0.002), whereby carbon levels were greater in the spring and fall periods compared with that present in the summer and winter. Overall, seasonal trends in phytoplankton taxonomic composition appeared to be lake-specific overall showing considerable compositional changes from month to month (Figure 3). However, the winter phytoplankton assemblages were strikingly similar in all 7 lakes, when large numbers of phytoflagellates (mainly Chrysophyceae and Cryptophyceae) occurred during ice-cover periods (low light and temperatures < 4oC). The prominence of winter phyto-flagellates occurred regardless of the relatively large differences in biogeochemistry and trophic state among the lakes. The biomass of this winter assemblages were significant contribution to the cumulative biomass of measured during the 7 months of ice-free conditions in 2011-12 (~25 %). Thus, we hypothesized that ability of phyto-flagellate populations to employ mixotrophy allowed them to sustain viable populations under the ice during the winter months. _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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LAKE ACACIA CHARACTERIZATION BY LOSS ON IGNITION CARBON AND DIATOM ASSEMBLAGES

Ben C. Conklin1, Jordyn T. Stoll1, and Julie A. Wolin1

1Department of Biological, Geological and Environment Sciences, Cleveland State University, Cleveland, OH 44115 USA

The characterization of lake habit and history was conducted by analyzing a benthic sediment core from Lake Acacia. Lake Acacia, located in Cleveland MetroParks Acacia Reservation, was cored during the summer of 2013 as part of the Urban Lake Assessment Project. This 107cm core record spans approximately 60 years of deposition. Lake Acacia was created between the early 1950’s and 1960’s based on preliminary assessment of historic topographic maps of the area. Loss on ignition carbon (LOI) analysis of this core, yielded preliminary data regarding the productivity of the lake over time and provided a basis for sample selection for further analysis with diatom microfossils. Samples were selected based on vertical shifts in the organic carbon, indicating a possible change in productivity. Diatom community composition will be related to the pattern of productivity, in order determine water quality changes in Lake Acacia over time. This study will be paired with GIS analysis of land use throughout the history of Lake Acacia to determine if water quality changes are correlated to changes in land use.

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DIATOMS INDICATE FREQUENT NITROGEN STRESS IN GREAT LAKES COASTAL WETLANDS

Gabrielle M. Costello1, Steven N. Francoeur1, and Matthew J. Cooper2

1 Biology Department, Eastern Michigan University, Ypsilanti, MI 48197 USA 2 Institute for Great Lakes Research, Department of Biology, Central Michigan University, Brooks 186, Mount Pleasant, MI 48859 USA

Phosphorus is typically considered to be the limiting nutrient for algae in most aquatic habitats in the Great Lakes region. We analyzed benthic algal community structure, measured dissolved nutrient concentrations, and used nutrient diffusing substrata (NDS) to infer nitrogen (N) scarcity in 28 coastal wetlands of Lakes Michigan and Huron. N fertilization increased algal biomass in 13 of 28 wetlands. The relative abundance of N-fixing diatoms (Epithemia and Rhopalodia) was significantly higher in N-limited wetlands, positively correlated with the magnitude of N limitation, and negatively correlated with dissolved N concentrations. The high degree of concordance among all these measures confirms that algae in many Great Lakes coastal wetlands are often stressed by N scarcity.

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EVALUATING LINKS BETWEEN BENTHIC BIOFILMS AND WATER QUALITY PARAMETERS FOR STREAMS IN SOUTHEASTERN PENNSYLVANIA Daniella M. Daniels1, Shannon Bradley1, Kimberly A. Carrick1, Mariena Hurley1, and Hunter J. Carrick1

1Department of Biology & Institute for Great lakes Research, Central Michigan University, Mount Pleasant, MI 48859 USA The Susquehanna and Delaware Rivers serve as two key tributaries to important coastal ecosystems (Chesapeake Bay and Delaware Bay). In particular, the Susquehanna River flows south from New York, through Pennsylvania where it drains 40% of the landmass there. Extensive benthic algal mats have been observed in the river and its tributaries, which appear to be associated with large, diel oxygen swings (DOS) and depressed fish production. Given this, we conducted a regional study southeastern PA to evaluate the potential link between benthic biofilms and variation in important water quality parameters (conductivity, TN, TP, mat poly-P). Water quality was monitored at 6 river sites and 24 watershed sites in 2013 (grab samples, Sonde continuous data over 30 days). Benthic biofilms were collected and processed to measure chlorophyll, carbon, nitrogen, and phosphorus concentrations in the mat. Biofilm chlorophyll values ranged from 10 to 300 mg/m2 among the stream sites. The diatoms (Division Bacillariophyta) present in the biofilms were identified down to their lowest taxonomic unit using a research grade microscope. Diatoms were assigned to nutrient guilds based upon published nutrient optima (Potapova and Charles 2007). Our results indicate quantitative coherence between water quality parameters and biological proxies for stream productivity (TP, polyp and Chl). Further, the abundance of nutrient-tolerant diatom species (e.g., Navicula lanceolata, Nitzschia amphibia), and nutrient-sensitive species (e.g., Achnanthidium minutissimum, Cymbella turdigula) correlated predictably with water column TP and TN concentrations, as well as, the poly-P content of benthic mats. ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________

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PATTERNS IN DIATOM (BACILLARIOPHYTA) TAXONMIC DIVERSITY AMONG ISOLATED WETLANDS ON BEAVER ISLAND (MICHIGAN, USA) John Diller1 and Hunter J. Carrick1

1Department of Biology & Institute for Great Lakes Research, Central Michigan University, Central Michigan University, Mount Pleasant, MI 48859 Species diversity can be influenced by any number of factors, both biotic and abiotic in nature. The Laurentian Great Lakes represent 20% of the world’s freshwater and house considerable microbial diversity, some of which has declined over time (planktonic diatoms), given environmental changes in the Great Lakes (e.g., nutrient loading, toxic contaminants, introduction of invasive species). As such, twenty isolated lentic ecosystems were sampled on Beaver Island, Michigan (July 2013) to evaluate the factors most likely to regulate diatom biodiversity among ecosystems of varying size. The size of ecosystems sampled ranged more than 2-orders of magnitude (<1 to >250 ha). At each site, collections were made for biofilms growing on vascular plant material and pelagic water; sampling was performed at five points (2 m intervals) along 10 m transects (repeated twice). Biogeochemical conditions were determined on water samples collected at each site (pH, alkalinity, dissolved organic carbon, chlorophyll, and total phosphorus), while biological conditions (chlorophyll, diatom taxonomic composition) were measured on biofilms. Overall, diatom species richness was relatively high among the 20 sites sampled here (221 species were encountered). Diatom species richness varied as a function of ecosystem size, although the variance explained was modest (SAR regression, r2=0.30, p=0.024, n=20). Interestingly, diatom taxonomic composition exhibited strong, geographic patterns, whereby relatively distinct diatom assemblages were identified between interior island locations and perimeter sites as identified using complimentary multivariate analyses (hierarchical cluster and NDMS). These differences were likely attributed to the glacial history of the area, whereby the retreat of glacial ice sheets effectively led to the differential formation of aquatic ecosystems on Beaver Island with changes in lake levels. Given this, older ecosystems occupied the interior portion of the island (higher elevation); these ecosystems were biogeochemically dystrophic and the diatom assemblages (acidobiontic species) were adapted to lower dissolved organic carbon conditions (lower pH, alkalinity, and conductivity). Relatively young ecosystems were situated along the perimeter of the lake, whose biogeochemistry was characterized by higher inorganic carbon conditions (higher pH, alkalinity, and conductivity) and with a corresponding diatom flora (alkalibiontic species). A multivariate model was developed that improved predictions of diatom diversity from key biogeochemistry (pH, alkalinity, conductivity, TP; r2=0.62, p=0.001, n=20); this model accounted for the natural history differences among ecosystems that appeared to influence the diversity of diatoms assemblages. ________________________________________________________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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THE GENUS DELICATA IN THE UNITED STATES

Mark B. Edlund1 and Dennis Vander Meer2

1St. Croix Watershed Research Station, Science Museum of Minnesota, 16910 152nd St. N., Marine on St. Croix, Minnesota 55423 USA 2Rhithron Associates, Inc., 33 Fort Missoula Road, Missoula, Montana 59804

The genus Delicata was erected by Krammer in 2003 to accommodate the cymbelloid taxa around Cymbella delicatula. Delicata is characterized by asymmetry about the longitudinal axis, lack of apical pore fields and stigmata, dorsal deflection of the terminal raphe ends, and relatively fine striae. To date about a dozen taxa have been transferred to or described within the genus. Most of these are based on European collections; however, a few taxa have been described from disparate and tropical locations (e.g., New Caledonia, Celebes). Based on various federal survey efforts in the United States (New York, Lake Superior, Arkansas), several assemblages had abundant Delicata populations that could not be readily assigned to known taxa. We examined these US Delicata populations, documented their morphology, compared them to known taxa, and examined evidence for high intraspecific morphological variation that has been attributed to this group. Results suggest that several of the US taxa should be recognized as new species.

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DIATOMA EHRENBERGII – AN INTRODUCED SPECIES IN THE GREAT LAKES?

Mark B. Edlund1 and David R.L. Burge1

1St. Croix Watershed Research Station, Science Museum of Minnesota, Marine on St. Croix, Minnesota, 55047, USA

Diatoma ehrenbergii has become a common member of the nearshore plankton and periphyton in Lakes Michigan and Superior. This taxon grows attached or free-floating in zig-zag colonies; valves are characterized among Diatoma taxa by their large size, linear valve, capitate ends, and presence of a single terminal rimoportulae per valve. Paleolimnological analysis of nearshore cores from northern Lake Michigan show that this taxon did not appear until the mid-1990s. and that in the most recent core samples, Diatoma ehrenbergii can be found at nearly 5% abundance. Recent collections having this diatom come from northern Lake Michigan, southern Lake Michigan, and western Lake Superior, and include association with sloughed deposits of Cladophora that are potential habitats for botulism production. Earlier reports of this taxon in the Great Lakes (e.g., Stoermer and Yang 1969) have been determined to be misidentified specimens of Diatoma tenuis/elongatum.

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EFFECTS OF FISH INTRODUCTION ON THE DIATOM RECORD OF A CANADIAN SHEILD LAKE IN PARC NATIONAL DE LA MAURICIE, QUÉBEC

Karista Hudelson1, Isabelle Lavoie1, and Paul E. Drevnick2

1Institute National de la Recherche Scientifique, Centre Eau, Terre, Environnement, Québec, QC 2University of Michigan, School of Natural Resources and Environment, Ann Arbor

Lac Français in Parc National de la Mauricie, Québec, Canada, is home to a relic population of arctic charr (Salvelinus alpinus), one of the southernmost populations of charr in North America. Despite restricted use of the lake and the prohibition of fishing, the health of the Lac Français charr population has been in a slow but steady decline since the 1960s. The decline could be due to climate warming or localized habitat alterations due to historical logging, fishing activities, the introduction of four invasive fish species, and the temporary damming of the lake. The purpose of this study is to determine how the history of land and lake alterations has impacted the charr habitat. Analyses of the uppermost 18 cm of a Lac Français sediment core included lead isotope dating, quantification of biogenic silica, and identification of diatom frustules to species level. Our preliminary interpretation of the data focuses on the drop in the percentage of benthic diatoms/increase in Cyclotella pseudostelligera which occurred around 1940, coincident with the introduction of rock bass (Ambloplites rupestris) into the lake. Larval rock bass predate primarily on zooplankton, which could result in the observed decline in C. pseudostelligera predators and thus the sustained dominance of C. pseudostelligera. Other trends in the diatom record of this lake (sustained decrease in Cyclotella bodanica beginning around 1910, increase in Fragilaria crotonensis from around 1910 to 1960) are evident but, to our knowledge, do not correspond with events from the human history of the lake.

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PHYTOPLANKTON RESPONSE TO NUTRIENT ENRICHMENT IN LAKES MICHIGAN AND SUPERIOR: A LINK BETWEEN GROWTH AND POLY-P Gary J.E. Michaud1 and Hunter J. Carrick1

Department of Biology & Institute for Great Lakes Research, Central Michigan University, Mount Pleasant, MI 48859 USA The Lake Michigan ecosystem has undergone systemic changes, such that the trophic state of the lake appeared to have changed (oligotrophication) over the past 10 years; the lake now supports levels of phytoplankton biomass and water column nutrients that are similar to those in Lake Superior. Given this, we conducted a series of experiments to determine whether phytoplankton biomass (chl) in the lake was limited by phosphorus (P), nitrogen (N), or both nutrients, and if the degree of limitation had changed compared with historical estimates of limitation. Experiments were performed on water samples collected from both near and offshore sites in southern Lake Michigan and central Lake Superior during three major thermal periods in each lake to account for seasonality (mixing, mid-stratification, and late stratification periods). Water samples were collected using clean 5-L Niskin bottles and placed in shaded carboys (10-liters). Once back in the lab, lake water was dispensed (0.5 liter) into 8 1-liter flasks, whereby P, N, and both N+P was added to duplicate flasks in order to double the concentrations in ambient lake water (2x2 factorial design). The experimental bottles were incubated in a plant growth chamber (ambient temperature, light, and day-length cycle) and sampled daily (end of the dark cycle) to determine in vivo fluorescence. Experiments were terminated when the phytoplankton had reached a growth plateau (~2 weeks), at which time final chl, total phosphorus (TP), and polyphosphate (polyP) concentrations were determined. Final chl concentrations varied among treatments and sampling locations (near vs. offshore), but not seasons (two-way ANOVA, F=1,500, p<0.0001). Chlorophyll was consistently higher in the P and N+P treatments, which indicated phytoplankton biomass was P-limited. This was true for both Lakes Michigan and Superior. Interestingly, phytoplankton growth rates from our experiments were inversely correlated with the TP-polyP ratio in both lakes (Lake Michigan, Pearson rank r= -0.49, p=0.0001; Lake Superior, Pearson rank r= -0.31, p=0.037). The results indicated that while both lakes were P-limited, the degree of P limitation in Lake Michigan appeared to be more acute compared with Lake Superior, and the degree of ploy-P storage was a reliable indicator of phytoplankton growth potential in both lakes.

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RELATING DIATOM ASSEMBLAGES TO SUB-WATERSHED CLUSTERS OF THE DELAWARE RIVER WATERSHED INITIATIVE

Alison Minerovic1 and Frank Acker1

1Patrick Center for Environmental Research, The Academy of Natural Sciences of Drexel University, Philadelphia, PA 19103 USA

The Delaware River Watershed Initiative (DRWI) is a collaborative effort to protect and restore water quality in the Delaware River basin. The DRWI focuses its efforts in eight sub-watershed “clusters,” comprising approximately 25% of the river basin and include portions of Delaware, New York, New Jersey, and Pennsylvania. Each cluster is characterized and threatened by unique, complex stressors, and targeted for its potential to measure impact. The Academy of Natural Sciences’ DRWI Team has designed and is implementing a comprehensive monitoring plan at over 300 project sites, with concentrated attention at 35 representative “integrative” sites to understand baseline conditions and trends in each of the clusters. We utilize fish, macroinvertebrates, algae, and salamanders as bioindicators, along with extensive water chemistry, in-stream habitat and riparian forest data to understand current conditions and monitor changes in water quality. Using algal assemblages (diatoms and soft-bodied) at each integrative site, along with physical and chemical data, we present current baseline ecological conditions in each cluster. “Restoration” clusters including Upstream Suburban Philadelphia (USP), Brandywine-Christina (BWC), Middle Schuylkill (MS), and New Jersey Highlands (NJH) clusters are characterized by elevated nutrient concentrations, higher pH and conductivity, and high siltation. Conversely, three “conservation” clusters including Poconos-Kittatinny (PK), Upper Lehigh (UL) and Schuylkill Highlands (SH) indicate oligo- to mesotrophic conditions, and low conductivity and salinity. For more information on the DRWI and its monitoring efforts, please visit http://www.ansp.org/drwi

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A CLOSER LOOK AT ENCYONEMA REIMERI Nick Schulte1, Elaine Jordan2, James Woodell2, Mac Flack2, Irene Tunno2, Sabrina Kamae2, Sergio Mendoza2, Joanna Gauthier2, Blamaki Behnaz2, Eilleen Salas2, David Burge3, Sylvia Lee4, and Mark Edlund3

1Department of Biology, Florida International University, Miami, FL 33199 2Ecology and Systematics of Diatoms class, Iowa Lakeside Laboratory, Milford, IA 3St. Croix Watershed Research Station, Science Museum of Minnesota, 16910 152nd St. N., Marine on St. Croix, Minnesota 55423 USA 4Cary Institute, Milbrook, NY 12545 Encyonema reimeri was described in 2009 by Spaulding et al. (Proc. ANSP 160:57) from West Lake Okoboji, Iowa. Although recognized as a new taxon, earlier reports considered this species under the names Encyonema muelleri or Encyonema ventricosum fo. muelleri. As a class project for the 2015 Ecology and Systematics of Diatoms class at Iowa Lakeside Laboratory, the morphology, allometry, and sexual reproduction of Encyonema reimeri was investigated. Collections made on 18 May 2015 showed a bimodal distribution of cell sizes that extended the upper size range known for this taxon, a positive relationship between valve length and breadth, and no apparent relationship between striae density and cell size. The class returned to collect new material after two weeks and found that the size distribution of cells has shifted downward and that there was evidence that the population was undergoing sexual reproduction. Two gametangial cells were paired in a copulation mucilage and each produced two isogametes. Pairing and fertilization most like followed Geitler's Normal Type 1c reproduction with no apparent relationship between gametangial cells and expanding auxospores. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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PLIO-PLEISTOCENE DIATOMS FROM THREE EAST AFRICAN RIFT LAKES Jeffery R. Stone1, Karlyn S. Westover1, Matthew D. Brindle1, and Joseph Mohan1

1Department of Earth and Environmental Systems, Indiana State University, Terre Haute, Indiana, USA, 47809 Over 2,000 meters of drill-core records from East African paleo-lakes have been collected in the past two years as part of the HSPDP collaborative research initiative. The sites for these drill-core materials were carefully selected to match the age and locations of world-class paleo-anthropologic sites where thick lacustrine deposits have been noted. The objectives of this research project include the assembly of high-resolution paleo-climatological and paleo-environmental records spanning the past ~4 million years in Eastern Africa and to use this information to test hypotheses linking climate change to evolutionary adaptations. Diatom analyses are a pivotal component of this research, providing much of the fundamental framework for reconstructing paleo-limnological responses. Here we present some of our initial observations on the diatom taxonomy and paleo-ecological inferences, including those from three lakes: the Northern Awash River Valley in Northern Ethiopia (Middle Pliocene), Tugen Hills in Central Ethiopia (Late Pliocene), and the western edge of Lake Turkana in Northern Kenya (Late Pliocene-Early Pleistocene). ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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DIATOM SURVEY OF LAGO DI RIPASOTTILE AND LAGO LUNGO, THE RIETI BASIN, LAZIO, ITALY Irene Tunno1, Paula Noble2, and Claire Archer2 1Department of Geography, University of Nevada, Reno 89557 USA 2Department of Geological Sciences and Engineering, University of Nevada, Reno 89557 USA A survey of diatoms from surface water habitats was conducted on two adjacent lakes and surrounding wetlands in the Rieti basin, 90 km NE of Rome, with the goal of assessing the ecologic associations of taxa in the modern environment. These lakes are remnant water bodies in an intermontaine alluvial basin that, in the past, were interconnected and have undergone significant drainage and alteration. Today, both lakes are eutrophic, alkaline systems, surrounded by agricultural fields, and wetlands dominated by phragmites. Ripasotille has higher TDS (680 vs. 545 mg/L), and hardness (130 mg/L vs. 90 mg/L) whereas Lungo until recently was hypereutrophic, is slightly smaller, and has a smaller perimeter to surface area ratio and smaller watershed. Samples taken along the perimeter in the phragmites zone show a periphyton dominated by Amphora, Gomphonema, Gyrosigma, several species of small chain-forming fragilarioids (including Staurosira construens, S. venter, B. brevistrata), adnate monoraphids (e.g. Planothidium and Cocconeis) and naviculoids (Navicula, Placoneis, Neidium, Craticula). A small pond draining into Lungo also provides abundant Fragilaria dilatata and Synedra spp. The largest difference between the lakes is the phytoplankton; Aulacoseira granulata dominated Ripasottile during our sampling period, along with tychoplanktonic Staurosirella, and C. ocellata dominated Lungo, followed by small Stephanodiscus. Examination of the core top from each lake reveals a composite of the last 1-2 years and indicates that Ripasottile Plankton:Periphyton ratios are smaller than Lungo, likely because of the larger watershed and littoral zones in Ripasottile. These data will be useful in interpreting paleoenvironmental significance of down core changes under study in both lakes. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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TWO NEW EUNOTIA SPECIES FROM THE TABLE MOUNTAIN CHURÍ-TEPUI, CHIMANTÁ MASSIF, VENEZUELA

Jana Veselá1, Markéta Bohunická2, and Jan Kaštovský2

1Diatom Herbarium, The Academy of Natural Sciences of Drexel University, 1900 Benjamin Franklin Pway, Philadelphia, PA 19103, USA 2Department of Botany, Faculty of Science, University of South Bohemia, Na Zlaté stoce 1, České Budějovice, CZ-37505, Czech Republic

Table mountains (tepuis) in northern South America represent one of the most unique ecosystems in the world. The largest complex of tepuis, the Chimantá Massif, consists of eleven table mountains, with Churí-tepui being one of them. During the expedition on top of Churí-tepui in 2012, a number of interesting microalgae were found. Among several unusual cyanobacteria and green algae, a number of unfamiliar diatom species were encountered. Two of them, belonging to the genus Eunotia, are proposed as species new to science. Eunotia churiensis sp. nov. and E. multirimoportulata sp. nov. both share a unique feature, a considerably higher number of rimoportulae per valve (3 to 8), which was observed only once within this genus up to date (from a relatively close locality). On top of it, this character is highly variable in terms of number of rimoportulae per valve apex, and in the arrangement (solitary, in groups). Besides this character, both taxa have notably large frustules, both somewhat resembling E. tetraodon in shape, and both share an uncommon valve surface pattern. Despite the high morphological similarity, these species can be distinguished based on curvature of the valve crests, length-to-with ratio, number of rimoportulae per valve, and perhaps ecology.

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DIATOMS FROM SHIP BALLAST SEDIMENTS Maria Célia Villac1, Irena Kaczmarska1, and James M. Ehrman2

1Dept. Biology, Mount Allison University, 63B York St., Sackville, NB E4L 1G7, Canada 2Digital Microscopy Facility, Mount Allison University, 63B York St., Sackville, NB E4L 1G7, Canada We will present to you the amazing biodiversity of diatoms transported in the sediments accumulated on the bottom of ballast tanks of ships arriving at Canadian ports on the West coast, East coast, and the Great Lakes during 2007 to 2009 (n=142 samples). Species richness was as high as 40 taxa per tank, including organisms in resting stages and cells that were considered alive at the time of sampling. Cell concentrations ranged from undetected to 1011 cells per tank. Although the lowest concentrations were often found in tanks that had undergone recent offshore ballast water exchange (BWE), the highest concentrations (109 to 1011 cells per tank) could be detected in any ballast management category: transoceanic with BWE, and intra-coastal with or without BWE. When fresh ballast sediment samples were inoculated into culture media, in vitro growth rates of total diatoms varied between 1.8 to 4.4 doublings per week. Our present inventory of 242 taxa corresponds to about 80% of the true potential biodiversity in the tanks. The most speciose genera were: Thalassiosira, Chaetoceros (spores), Cyclotella, Shionodiscus, Pseudo-nitzschia, Actinocyclus, Aulacoseira, Melosira, Podosira, Surirella, and Paralia. The following genera/families are among those for which diversity is still underestimated: Navicula, Nitzschia, Cymbellaceae, Fragilariaceae, and Pleurosigmataceae. Multivariate analysis reduced our data set to three assemblage types. We hypothesized that propagule pressure of these potential colonizers may be enhanced due to repeated introduction attempts by multiple ships of different ballast management categories, but which actually carried the same assemblage type. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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PALEOLIMNOLOGICAL INDICATORS IN A 6,300-YEAR SEDIMENT CORE FROM VOLO BOG, A SPHAGNUM WETLAND IN NORTHEASTERN ILLINOIS Naida Zulovic1, Michael Vujanovic1, Omar Morales Luna1, and Jennifer E. Slate1

1Department of Biology, Northeastern Illinois University, 5500 North St. Louis Avenue, Chicago, Illinois 60625 USA As Illinois’s only quaking bog, Volo Bog is unique due to the naturally acidic water caused by a floating mat of Sphagnum moss. We examined diatoms, chrysophytes, and loss-on-ignition from an 8.5-m core, spanning 6300 years, to determine the potential to infer changes in pH over time. Acidophilic diatoms (e.g. Eunotia) were present and unornamented chrysophyte cysts without a collar were abundant. We also identified nine other cyst morphotypes, and chrysophyte cysts were well preserved when diatoms were not. Percent organic matter was consistently high (75-93%) above 7 m, but decreased to <53% below 7.5 m. Further attention needs to be given to this transition, because it is not known when the Sphagnum mat developed. The diversity and excellent preservation of chrysophyte cysts suggests their potential to infer pH, especially for time periods in which diatoms dissolved. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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The NADS Program 2015: Notes

Central Michigan University Biological Station