Dr. Duane Moser, Dr. Jim Bruckner, Dr. Duane Moser, Dr. Jim Bruckner, and and

Dr. Jen FisherDr. Jen Fisher

10/28/0910/28/09

Microbial Biogeochemistry of Walker Lake, NV

duane.moser@dri.eduduane.moser@dri.edu

Walker Lake microbiology (justification)

• Fleeting opportunity to establish baseline trophic structure while lake is still viable for fisheries

• Little known about microbial communities in alkaline habitats or terminus lakes

Walker Lake micro (justification cont.)

• Almost nothing known about microbial community/function in this alkaline terminus lake

• Insights for management (e.g. oxygen depletion, sulfide and ammonia production, nutrient dynamics, food web structure, trophic status)

From Lake Task 6 Final Report

Microbial Biogeochemistry

Example: Internal N loading

Snapshot: Walker Lake (9/18/08)

Heroes: Ron Hershey and Jeramie Memmott From Walker Basin Task 6 report

DNA

Molecular ecology 16S rRNA gene

Molecular Ecology 16S rRNA

Walker Lake Microbial Communities

Neighbor-joining tree from four Walker Lake samples (16S rRNA gene). J.C. Bruckner

Select Environmental Chemistry Variables

Depth ODO SO4 H2S TOC DOC Fe Mn As

(m) (mg/l) (mg/l) (mg/l) (mg/l) (mg/l) (ppb) (ppb) (ppb)

0 6.62 3970 <0.03 43.2 42.4 35 6 1438

5 6.56 3970 <0.03 41.4 42.1 31 6 1392

10 6.48 3980 <0.03 42.2 40.9 40 6 1421

17.5 5.49 3960 <0.03 4.27 42.1 30 9 1463

18 4.66 3950 <0.03 42.3 41.9 24 11 1296

19 0.65 3930 <0.03 41.4 41.5 22 15 1300

22 0.1 3890 <0.03 38.1 40.6 17 23 1408

Epilimnion Metalimnion Hypolimnion

Data provided by Ron Hershey.

0 105 101 101 0 0 0 0 103 105

10 105 104 101 0 0 0 101 103 104

17.5 104 104 102 101 102 101 101 103 107

18 104 105 103 101 102 102 101 104 105

19 104 105 103 101 102 103 102 104 106

22 104 105 104 102 104 104 105 104 104

SS 106 105 104 103 104 103 104 104 106

SD 105 105 104 104 104 104 105 105 105

Aerobes FermenterNitrate

Reducer Sulfate

Reducer Sulfur

Reducer

Iron FeNTA

Reducer

IronCitrate

Reducer ArsenateReducer

ArseniteOxidizer

Depth(m)

Epilimnion Metalimnion Hypolimnion Sediment

Abundances of Major Microbial Physiotypes

Cells per mL

Depth (m) Sulfate Sulfide SRBs 34S-SO4 34S-H2S total

0 3970 <0.03 0 6.9 ----- ----

10 3970 <0.03 0 7.0 ----- ----

17.5 3980 <0.03 0 6.9 ----- ----

18 3950 <0.03 101 7.0 ----- ----

19 3930 <0.03 101 7.1 ---- ----

22 3890 <0.03 102 6.9 -32.9 39.8

Stable Isotopic Evidence for Sulfate Reduction

Sort of

Anna Szynkiewicz and Lisa Pratt, Indiana University

Epilimnion Metalimnion Hypolimnion

Permanganate assay for arsenite oxidation

Sulfide/HCl assay for arsenate reduction

Arsenic Biogeochemisty

Jen Fisher

IC-ICP-MS data generated by Britta Planer-Friedrich at Universität Bayreuth, Germany

Flow cytometric cell counts (RBD-3000)

An Interesting Observation

Snapshot: Walker Lake (9/18/08)

YSI data courtesy Jeramie Memmott and Chris Fritsen, DRI

Autofluoroescent cells

Total cells

Dissolved O2

Temp

Snapshot: Walker Lake (9/18/08)

YSI data courtesy Jeramie Memmott and Chris Fritsen, DRI

Chlorophyll a

Phycobillins

Epifluorescence microscopy: Zeiss AxioScop, rhodamine filter (L), phase contrast (R)

Walker Lake Mystery Microbe.

Cyanobacteria-like 16S rRNA Clones

Neighbor-joining tree, 16S rRNA gene

Photosynthetic Electron Transport in Cyanobacteria

SQR = sulfide quinone reductase. Wolf-Simon…Andrew Knoll, Iron, Sulfur, Oxygen, and Water: Geochemical implications of facultative anoxygenic photosynthesis in cyanobacteria and the slow rise of oxygen. AGU Poster 2008

Conclusions

This project was funded through Congress by Public Law 109-103, Section 208 and awarded to the Nevada System of Higher Education under the administration of the Department of the Interior, U.S. Bureau of Reclamation with supplemental support to Jim Bruckner provided by the DRI/DEES postdoc program. Special thanks to Chris Fritsen and crew for help with lake access and Ron Hershey, Britta Planer-Friedrich, and Anna Szynkiewicz and Lisa Pratt for aquatic chemistry. Thanks to Jeremy Dodsworth and Brian Hedlund for assistance with sampling and dissolved gas analysis. Thanks also to Journet Wallace, Julius DeLeon, Susanna Blunt and other students from our lab who assisted with sample processing.

• Diverse and novel alkaliphilic microbial community

• Metal-driven redox cycling (As, Fe) appear to be present (important?)

• Microbial tipping point to Mono Lake-like microbial communities may have already occurred

• Historical sulfide accumulations in hypolimnion may now be consumed by As reduction and facultatively anaerobic cyanobacteria

Aquatic Chemistry Summary

Data from Ron Hershey.

Environmental Microbiology Lab

Wolf-Simon…Andrew Knoll, Iron, Sulfur, Oxygen, and Water: Geochemical implications of facultative anoxygenic photosynthesis in cyanobacteria and the slow rise of oxygen. AGU Poster 2008

Fluxes denoted as: a, anoxygenic photosynthesis; b, oxygenic photosynthesis; c, sulfide oxidation by disproportionation or phototrophic S-oxidizers; d, S0 respiration by cyanobacteria, e, sulfate reduction; f, S0-OM export/ballasting; g, pyrite formation; h, aerobic respiration;i, OM export and j, O2 export.

Arsenic speciation determined by IC-ICP-MS

22 m 9/18/09