Microbial Biogeochemistry of
Walker Lake, NV
Dr. Duane Moser, Dr. Jim Bruckner, and
Dr. Jen Fisher
10/28/09
duane.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)
Microbial Biogeochemistry
Example: Internal N loading
From Lake Task 6 Final Report
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.
Abundances of Major Microbial Physiotypes
Cells per mL
Iron
FeNTA
Nitrate Sulfate
Sulfur
Fermenter
Reducer Reducer Reducer Reducer
Iron
Citrate
Reducer
Depth
(m)
Aerobes
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
Epilimnion
Metalimnion
Hypolimnion
Arsenate Arsenite
Reducer Oxidizer
Sediment
Stable Isotopic Evidence for Sulfate Reduction
Sort of
Depth (m)
Sulfate
Sulfide
SRBs
d34S-SO4
d34S-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
Epilimnion
Metalimnion
Hypolimnion
Anna Szynkiewicz and Lisa Pratt, Indiana University
Arsenic Biogeochemisty
Permanganate assay for arsenite oxidation
Sulfide/HCl assay for arsenate reduction
Jen Fisher
IC-ICP-MS data generated by Britta Planer-Friedrich at Universität Bayreuth, Germany
An Interesting Observation
Flow cytometric cell counts (RBD-3000)
Snapshot: Walker Lake (9/18/08)
Autofluoroescent cells
Total cells
Dissolved O2
Temp
YSI data courtesy Jeramie Memmott and Chris Fritsen, DRI
Snapshot: Walker Lake (9/18/08)
Chlorophyll a
Phycobillins
YSI data courtesy Jeramie Memmott and Chris Fritsen, DRI
Walker Lake Mystery Microbe.
Epifluorescence microscopy: Zeiss AxioScop, rhodamine filter (L), phase contrast (R)
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
• 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.
Aquatic Chemistry Summary
Data from Ron Hershey.
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-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
Arsenic speciation determined by IC-ICP-MS
22 m 9/18/09