Dr. Duane Moser, Dr. Jim Bruckner, and

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Microbial Biogeochemistry of Walker Lake, NV
Dr. Duane Moser, Dr. Jim Bruckner, and Dr. Jen
Fisher 10/28/09
duane.moser_at_dri.edu
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• 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

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• 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)

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Microbial Biogeochemistry
Example Internal N loading
From Lake Task 6 Final Report
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Snapshot Walker Lake (9/18/08)
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DNA

• Molecular ecology 16S rRNA gene

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Molecular Ecology 16S rRNA
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• 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 lt0.03 43.2 42.4 35 6 1438
5 6.56 3970 lt0.03 41.4 42.1 31 6 1392
10 6.48 3980 lt0.03 42.2 40.9 40 6 1421
17.5 5.49 3960 lt0.03 4.27 42.1 30 9 1463
18 4.66 3950 lt0.03 42.3 41.9 24 11 1296
19 0.65 3930 lt0.03 41.4 41.5 22 15 1300
22 0.1 3890 lt0.03 38.1 40.6 17 23 1408
Data provided by Ron Hershey.
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Abundances of Major Microbial Physiotypes
Cells per mL








Iron FeNTA Reducer
Iron Citrate Reducer
Aerobes

Nitrate Reducer
Sulfate Reducer
Sulfur Reducer
Arsenate Reducer
Arsenite Oxidizer
Depth (m)
Fermenter








5

0

10
5
5
4
4
4
4
5
5
5
SD

10

10

10

10

10

10

10

10

10

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Stable Isotopic Evidence for Sulfate
Reduction Sort of
Depth (m) Sulfate Sulfide SRBs d34S-SO4 d34S-H2S total
0 3970 lt0.03 0 6.9 ----- ----
10 3970 lt0.03 0 7.0 ----- ----
17.5 3980 lt0.03 0 6.9 ----- ----
18 3950 lt0.03 101 7.0 ----- ----
19 3930 lt0.03 101 7.1 ---- ----
22 3890 lt0.03 102 6.9 -32.9 39.8
Anna Szynkiewicz and Lisa Pratt, Indiana
University
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Arsenic Biogeochemisty
Jen Fisher
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IC-ICP-MS data generated by Britta
Planer-Friedrich at Universität Bayreuth, Germany
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An Interesting Observation
Flow cytometric cell counts (RBD-3000)
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Cyanobacteria-like 16S rRNA Clones
Neighbor-joining tree, 16S rRNA gene
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Photosynthetic Electron Transport in
Cyanobacteria
SQR sulfide quinone reductase.
Wolf-SimonAndrew Knoll, Iron, Sulfur, Oxygen,
and Water Geochemical implications of
facultative anoxygenic photosynthesis in
cyanobacteria and the slow rise of oxygen. AGU
Poster 2008
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Conclusions

• 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

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.
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Aquatic Chemistry Summary
Data from Ron Hershey.
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Environmental Microbiology Lab
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.
Wolf-SimonAndrew Knoll, Iron, Sulfur, Oxygen,
and Water Geochemical implications of
facultative anoxygenic photosynthesis in
cyanobacteria and the slow rise of oxygen. AGU
Poster 2008
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Arsenic speciation determined by IC-ICP-MS
22 m 9/18/09