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Stream Organisms
Uni1: Module 4, Lecture 4
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s2
Objectives
Students will be able to: describe major characteristics of autotrophs. categorize autotrophs types by location. contrast seasonal variations in the growth of
periphyton communities. compare and contrast the four types of macrophytes. define and provide examples of stream
macroinvertebrates. provide examples of morphological adaptations to
water and interpret their significance. diagram the life cycles of aquatic insects. compare and contrast the functional roles of
macroinvertebrates in organic matter processing.
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s3
The slides on stream organisms are divided into three sections: Autotrophs Invertebrates Fish
Stream organisms
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s4www.glifwc.org/
Autotrophs
Autotrophs are organisms that acquire materials from the environment and energy from sunlight in the process of producing organic matter.
Green plants, diatoms and filamentous algae, some bacteria, and some protists make up the autotrophs in lotic systems.
In contrast, heterotrophs, such as fungi or fish gain nutrients and energy by processing dead organic matter.
Functionally, autotrophs serve lotic communities by making organic energy available to consumer organisms at higher trophic levels.
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s5
Benthic autotrophs
Benthic autotrophs grow on virtually all surfaces receiving light in flowing waters and are collectively referred to as the periphyton community.
Habitat specialization allows for classification of benthic autotrophs into groups; Species that grow on stones (epilithon) Species that grow on soft sediments (epipelon) Species that grow on other plants (epiphyton)
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s6
Periphyton
Periphyton is a complex matrix of algae and heterotrophic microbes attached to submerged substrata in almost all aquatic ecosystems.
It serves as an important food source for invertebrates and some fish, and it can be an important sorber of contaminants.
www.duluthstreams.org/understanding/algae.html
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s7
Hoffman Image Gallery
Hoffman Image Gallery
Periphyton components
Lotic phytoplankton include: Algae Protozoans Cyanobacteria
These are small enough to remain suspended in the water column and be transported by currents.
phytoflagellates (euglenophyta)
Biodidac
www.cawthron.org.nz/periphyton_image.htm
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s8
University of Wisconsin Botanical Images Collection
Hoffman Image Gallery
Hoffman Image Gallery
Attached and benthic populations
Many blue-green algae grow attached on the surface of rocks and stones (epilithic forms), on submerged plants (epiphytic forms) or on the bottom sediments (epipelic forms, or the benthos) of rivers.
The epiphytic flora of lotic communities is usually dominated by diatoms and green algae, and blue-greens are of less importance in this community.
blue-green algae (cyanobacteria)
Diatoms
Biodidac
green algae (chlorophyta)
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s9
Seasonal succession in periphyton communities
Diatoms dominate during the winter, spring, and early summer
Green algae and cyanobacteria populations increase during the summer
Benthic autotrophs tends to decrease during the summer as a result of increased shading, increasing again in fall
www.urbanrivers.org/web_images/diatoms.gif
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s10
Distribution of autotrophs: Lakes vs rivers
Image from Allan, Fig. 4.12, p. 105
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s11
Algal primary productivity
Photosynthesis-Light - Temperature-Nutrient - Chronic toxicity-Velocity
Respiration/Excretion
Grazing
Mortality
-Acute toxicity
-High temperature
Sinking
- Velocity
- Stress
Algal biomassWashout-Velocity-Available substrate
Loading Turbulent diffusion
www.epa.gov/waterscience/pc/wqnews/algal.gif
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s12
Macrophytes
Westlake (1975a) identified four primary growth forms: 1) Emergents occurring on river banks and shoals
typically are rooted in soil that is near or below the waterline and have aerial leaves and reproductive structures;
2) Floating-leaved species occupy margins of slow current areas, are rooted in submerged soils, and have aerial or floating leaves and reproductive structures;
3) Free-floating species are typically not attached to the substrate and often form mats that entangle other species in slow flowing tropical rivers;
4) Submerged species are rooted to the substrate, have submerged leaves, and are located in mid-channel to the point of insufficient light penetration.
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s13
Macrophyte growth forms
Emergents: banks and shoals
Floating-leaved: stream margins
Free-floating: slow (tropical) rivers
Submerged: midstream (limited by light penetration, current speed, and substrate type)
Emergent
cce.cornell.edu/onondaga/watersheds/images/milfoil.jpg
Floating-leaved
www.sthubertsisle.com/Lily%20pads.jpg
Free-floating
http://lakes.chebucto.org/VIEW/PIC/duckweed.jpg
Submerged
http://riverwoods.ces.fau.edu/riverwoods/display.ihtml?pic=../photos/birdseyenupharsm.jpg
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s14
Aquatic macrophytes do not show adaptations to life in rivers and streams.
Consequently, they are limited to areas of little current and suitable substrate.
Most commonly these areas include; deltas, backwaters, pools, beaver impoundments, margins, banks, shoals, and contiguous wetlands.
Macrophyte growth forms
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s15
Basic macrophyte structure
Success and maintenance of macrophyte populations in significant current can be attributed to a few adaptive characteristics.
Tough, flexible stems and leaves; attachment by adventitious roots, rhizomes, or stolons; and vegetative reproduction characterize most lotic macrophyte species (Hynes, 1970; Westlake, 1975a).
aquat1.ifas.ufl.edu/zizaqu2.jpg
Stems and leaves
Adventitious roots
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s16
www.glifwc.org/
Patchy distribution of macrophytes
Macrophyte distribution and abundance changes annually
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s17
Macrophyte consumers
Even in streams that show high macrophyte productivity, a relatively small fraction of the streams total energy results from macrophyte production.
The fate of this primary production includes herbivory, secretion of dissolved organic matter, and decomposition.
Herbivory is carried out in large part by vertebrates, including waterfowl, manatee, grass carp, muskrat (Westlake, 1975b), and moose.
http://www.fcsc.usgs.gov/posters/Nonindigenous/Nonindigenous_Crustaceans/nonindigenous_crustaceans.html
http://images.fws.gov/www.epa.gov/25water/exotic/slide15.jpg
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s18
Stream invertebrates
Much of the aquatic life in streams is composed of benthic macroinvertebrates.
The term macroinvertebrate includes clams, crayfish, worms, and insects.
Macroinvertebrates do not have internal skeletons, are larger than 5 microns, and, typically, live on a stream substrate (bottom, woody debris, macrophyte, etc..)
photo source: North American Benthological Society
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s19
Insects
Adaptation to life in streams and rivers
Introduction to taxonomy
General life cycle Introduction to
functional roles
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s20
Morphological adaptations to running water
Adaptation Significance Representative Groups and Structures
Comments
Dorsoventrally Flat
Allows crawling in slow current boundary layer on substrate
Odonata – GomphidaeTrichoptera - Glossosoma
Streamlining Fusiform body minimizes resistance to current
Ephemeroptera – BaetisDiptera - Simulium
Relatively rare body form
Reduced projecting structures
Reduces resistance to current
Ephemeroptera - Baetis Large lateral structures exist in some groups
Suckers Attach to smooth surfaces
Diptera - Blephariceridae Rare adaptation
Friction Pads Increased contact reduces chances of being dislodged
Coleoptera - Psephinus
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s21
Morphological adaptations to running water
Adaptation Significance Representative Groups and Structures
Comments
Small size Allows use of slow-current boundary layer on top of substrate
Stream animals are smaller than stillwater relatives
Silk and sticky secretions
Attachment to stones in swift current
Diptera – SimuliumTrichoptera - Hydropsychidae
Ballast Cases made of large stones Trichoptera - Goera
Attachment claws /dorsal processes
Stout claws aid in attachment to plants
Ephemeroptera - Ephemerella
Reduced power of flight
Prevents emigration from small habitats
Plecoptera - Allocapnia Reduces dispersal ability
Hairy bodies Keeps sand/soil particles away while burrowing
Ephemeroptera - Hexagenia Allows water flow over body
Hooks or Grapples
Attachment to rough areas of substrates
Coleoptera - Elmidae
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s22
Classification of insects
Common Name
Human Canada Goose Lake Darner Dragonfly Giant water bug
Kingdom Animalia Animalia Animalia Animalia
Phylum Chordata Chordata Arthropoda Arthropoda
Class Mammalia Aves Insecta Insecta
Order Primate Anseriformes Odonata Hemiptera
Family Hominidae Anatidae Aeshnidae Belostomatidae
Genus Homo Branta Aeshna Lethocerus
species sapiens canadensis eremita americanus
Author Scudder (Leidy)www.usask.ca/biology/skabugs/idclass/classify.html
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s23
Aquatic insect orders
Order
Number of North American aquatic species
(estimated)
Larvae Adults
Ephemeroptera (mayflies) 572
Odonata (dragonflies and damselflies)
357
Plecoptera (stoneflies)
582
Trichoptera (caddisflies) 1215+
www.usask.ca/biology/skabugs/
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Developed by: Merrick, Richards Updated: August 2003 U1-m4-s24
Aquatic insect orders
Order
Number of North American aquatic species
(estimated)
Larvae Adults
Diptera (flies and midges)
4662+
Hemiptera (true bugs)
410
Coleoptera (beetles)
1842+www.usask.ca/biology/skabugs/
www.usask.ca/biology/skabugs/
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Developed by: Merrick, Richards Updated: August 2003 U1-m4-s25
Aquatic insect orders
Order
Number of North American aquatic species
(estimated)
Larvae Adults
Megaloptera (alderflies and dobsonflies)
43
Neuroptera (spongilla flies)
6
Lepidoptera (moths)
635
Hymenoptera (parasitic wasps) 55
www.usask.ca/biology/skabugs/
www.usask.ca/biology/skabugs/
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Developed by: Merrick, Richards Updated: August 2003 U1-m4-s26
Life cycles of aquatic Insects
Holometabolous insects pass through a complete metamorphosis that consists of four stages: 1) Egg > immature (larva)
> Pupa > Adult 2) During pupal stage
adult characteristics develop
3) Examples include; caddisflies and dipterans such as blackflies
Holometabolous Hemimetabolous
fig. 14.2, p. 179 from Allan and Cushing
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s27
Life cycles of aquatic Insects
Hemimetabolous insects pass through three stages in their life cycle: 1) Egg > Immature
(nymph) > Adult 2) Adults are
terrestrial 3) Examples include;
stoneflies, mayflies, and dragonflies
Holometabolous Hemimetabolous
fig. 14.2, p. 179 from Allan and Cushing
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s28
www.usask.ca/biology/skabugs/lifecycle/insectlifecycle.html
Hemimetabolous life cycle
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s29
Adult
Holometabolous life cycle
Complete metamorphosis in the caddisfly Hydropsyche sp. Larva Pupa Adult
www.usask.ca/biology/skabugs/lifecycle/insectlifecycle.html
www.usask.ca/biology/skabugs/lifecycle/insectlifecycle.html
www.usask.ca/biology/skabugs/lifecycle/insectlifecycle.html
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s30
Life cycle length
Multivoltine – several generations per year
Univoltine – one generation per year
Semivoltine – one generation every 2-3 years
Baetis sp., a common mayfly is noted to be univoltine at low elevation and warmer temperatures and semivoltine at high elevations and colder temperatures (Allan, 1995).
www.mendozaflyshop.com/images/6_01.jpg
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s31
Ecological roles
Macroinvertebrates play a variety of roles in food webs.
Fig. 4.9, p.53 in Allan and Cushing, 2001
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s32
Shredders Dominant food
Vascular macrophyte tissue Coarse particulate organic material (CPOM) Wood
Feeding mechanisms Herbivores - Chew and mine live macrophytes Detritivores - Chew on CPOM
Representatives Scathophagidae (dung flies) Tipulidae (crane flies)
Macroinvertebrate functional roles in organic matter processing
A caddisfly of the family Limnephilidae
www.oaa.pdx.edu/CAE/Programs/sti/pratt/feeding/inverts/shredder.html
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s33
Collectors Dominant food
Decompose fine particulate organic matter (FPOM) Feeding mechanisms
Filterers - Detritivores Gatherers - Detritivores
Representatives Filterers
• Hydropsychidae • Simulidae (black flies)
Gatherers• Elmidae (riffle beetles)• Chironomini• Baetis• Ephemerella• Hexagenia
Macroinvertebrate functional roles
A blackfly of the family Simulidae
A caddisfly of the family Hydroptilidae
www.oaa.pdx.edu/CAE/Programs/sti/pratt/feeding/inverts/collector.html
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s34
Scrapers Dominant food
Periphyton (attached algae) Material associated with periphyton
Feeding mechanisms Graze and scrape mineral and organic surfaces
Representatives Helicopsychidae Psephenidae (water pennies) Thaumaleidae (solitary midges) Glossosoma Heptagenia
Macroinvertebrate functional roles
A dipteran of the family Thaumaleidae
www.oaa.pdx.edu/CAE/Programs/sti/pratt/feeding/inverts/scraper.html
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s35
Predators Dominant food
Living animal tissue Feeding mechanisms
Engulfers - Attack prey and ingest whole animals Piercers - Pierce tissues, suck fluids
Representatives Engulfers
• Anisoptera (dragonflies)• Acroneuria• Corydalus (hellgrammites)
Piercers• Veliidae (water striders)• Corixidae (water boatmen)• Tabanidae (deerflies & horseflies)
Macroinvertebrate functional roles
A stonefly of the family Perlidae
A “true bug” of the family Notonectidae
www.oaa.pdx.edu/CAE/Programs/sti/pratt/feeding/inverts/predator.html
Developed by: Merrick, Richards Updated: August 2003 U1-m4-s36
Other macroinvertebrates
Annelids (leeches and aquatic worms)
Molluscs (clams, mussels, and snails)
Crustaceans (crayfish, amphipods, and mites)
http://www.usask.ca/biology/skabugs/
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