Transcript The Roles of Biogeochemistry and Aquatic Biota in Mercury Cycling in

The Roles of Biogeochemistry and
Aquatic Biota in Mercury Cycling in
Stream Ecosystems
Lia Chasar, Barbara Scudder, Robin Stewart, and
Amanda Bell
U.S. Department of Interior
U.S. Geological Survey
National Water-Quality Assessment Program
NAWQA Mercury Bioaccumulation Study
Mercury source strength
Food web
complexity
Methylation efficiency
Structure
Food chain length
After : T.E. Mumley & K.E. Abu-Saba, WEF
National TMDL Science and Policy
Conference Proceedings, Nov. 13-16, 2002
Objective

Evaluate the influence of environment and
food web characteristics on mercury
contamination in top predator fish
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Environmental factors
Climate/hydrodynamics
 Physicochemical
 Substrate
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Food web complexity
food web structure
 food chain length
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Ecological Approach
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Physical setting
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Food web base
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Periphyton (attached algae)
Microbial biofilms
Detritus
Seston
Consumers
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Hydrology
Water chemistry
Primary and secondary
Locally/regionally common species
Feeding relationships
Life history of target species
Lookout Creek, Oregon
Reference site, low % wetland
Site Selection
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3 study areas
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2 to 3 sites each
Landscape type
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1 urban
1-2 reference
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Rural or non-cultivated
Low and high % wetland
Nearby atmospheric
monitoring sites for Hg
Availability of target predator
fish species
Range of food web complexity
Evergreen River, Wisconsin
Reference site, low % wetland,
wetlands close proximity
Multimedia Sampling
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Surface Water
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Dissolved and particulate THg and
MeHg
DOC, SO4, suspended sediment
Major ions
Nutrients
DO, pH, conductance, alkalinity
Streamflow
Biota
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Benthic algae (THg and MeHg)
Aquatic invertebrates (THg and
MeHg)
Predator and forage fish (THg)
Little Wekiva River, Florida
Urban site
Conceptual Food Web
Forage Fish
sp. 1
Invertebrate
sp. 1
Forage
Fish sp. 2
Invertebrate
sp. 2
Predator Fish
Seston
Detritus
Biofilms
Periphyton
Aqueous
MeHg
Predator and Forage Fish
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Predator
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Forage
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1 target species
Skin-off fillets
2 species
Headless/gutless
12 individuals per species
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Age, length, weight, sex
Gut contents
THg
Stable isotopes (13C, 15N)
Continued…
Benthic Invertebrates
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Two species
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Locally common
Whole-body
Target 30+ individuals
per species
Collectors and grazers
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THg and MeHg
Stable isotopes (13C,
15N)
Continued…
Periphyton
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Twice, seasonal
Target substrates
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woody debris
rocks
sediment
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Analyses
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THg and MeHg
 Stable isotopes
(13C, 15N)
Bell and Scudder
(USGS - OFR 20041446); Bell & Scudder
(JAWRA Journal, in
press)
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Expected Food Webs
Predator Fish A
WILL
WIMC
GAFL
Cutthroat
Brown Trout
Largemouth Bass
Predator Fish B
Brook Trout
Forage Fish A
Sculpin
Creek Chub
Juvenile Sunfish
Forage Fish B
Dace
Shiner/Dace
Gambusia
Invertebrate A
Caddisfly
Caddisfly
Crayfish
Grass Shrimp
Invertebrate B
Mayfly
Mayfly
Mosquito Larvae
Sampled Food Webs
WILL
WIMC
GAFL
Predator Fish A
Cutthroat
Brown Trout
Largemouth Bass
Predator Fish B
Rainbow
Green Sunfish
Forage Fish A
Sculpin
Creek Chub
Juvenile Sunfish
Forage Fish B
Dace
Gambusia
Dace
Sculpin
Gambusia
Shiners/Mollys
Invertebrate A
Caddisfly
Snails
Caddisfly
Crayfish
Grass Shrimp
Amphipods
Invertebrate B
Mayfly
Crayfish
Mayfly
Caddisfly
Results
Invertebrate MeHg (ng g-1 dry wt)
Relationship of invertebrate MeHg
to aqueous MeHg
400
300
GAFL
WILL
WMIC
200
100
0
-100
-0.2
0.0
0.2
0.4
Filtered MeHg (ng L-1)
0.6
Forage Fish THg (ng g -1 dry wt)
Relationship of forage fish THg
to aqueous MeHg
1000
800
GAFL
WILL
WMIC
600
400
200
0
-200
-0.2
0.0
0.2
0.4
Filtered MeHg (ng L-1)
0.6
Relationship of predator fish THg
to aqueous MeHg
Predator THg (ng g -1 dry wt)
8000
6000
GAFL
WILL
WMIC
4000
2000
0
-0.2
0.0
0.2
0.4
Filtered MeHg (ng L-1)
0.6
7
7
6
6
5
5
4
4
3
3
2
2
1
1
0
0
100
0
20
40
60
DOC (mgC/L)
80
SUVA (L/mg-cm)
Log Kd MeHg
Partitioning of Hg appears to depend
on DOC Quantity and Quality
Bioaccumulation of Hg in invertebrates
appears to depend on DOC Quantity and
Quality
5
400
GAFL
WILL
WMIC
300
4
200
3
100
2
0
Invertebrates
1
0
20
40
60
DOC (mgC/L)
80
-100
100
MeHg (ng/g)
SUVA (L/mg-cm)
6
Bioaccumulation of Hg in forage fish
appears to depend on DOC Quantity and
Quality
5
1000
GAFL
WILL
WMIC
800
600
4
400
3
200
2
Forage Fish
1
0
20
40
60
DOC (mgC/L)
80
0
-200
100
Hg (ng/g)
SUVA (L/mg-cm)
6
Bioaccumulation of Hg in predator fish
appears to depend on DOC Quantity and
Quality
5
8000
GAFL
WILL
WMIC
6000
4
4000
Need to fill
in data gap
3
2
2000
Top Predators
1
0
20
40
60
DOC (mgC/L)
80
100
0
Hg (ng/g)
SUVA (L/mg-cm)
6
Particle A&B (c=3)
Invert A&B (c=3)
Forage fish A&B (n=6)
Top fish A&B (n=6)
Particle A&B (c=?)
Invert A&B (c=3)
Forage fish A&B (n=6)
Top fish A&B (n=6)
Log Tissue Mercury (g g-1 dry wt)
Tissue Hg increases with
Trophic Position
100
GAFL
WILL
WMIC
10
1
Urban sites
0.1
0.01
0.001
0.0001
-2
0
2
4
6
8
15N
10 12 14 16 18
Log Tissue Mercury (g g-1 dry wt.)
Patterns of Hg Bioaccumulation are
similar among most sites ( slopes)
10
GAFL
WILL
WMIC
1
Urban
Urban
Urban
Low
Low
High
High
Low
0.1
0.01
0.001
2
4
6
8
10
12
14
Adjusted 15N (GAFL - Santa Fe Gammarids)
Regression Statistics
Florida
Little
Wekiva
Santa
Fe
Oregon
St.
Mary’s
Beaverton
Lookout
Wisconsin
Evergreen
Oak
Pike
Slope
0.20
0.23
0.23
0.30
0.22
0.12
0.28
Adjusted
Intercept
-2.52
-2.53
-1.92
-3.01
-3.43
-1.84
-2.89
R2
0.20
0.89
0.52
0.38
0.94
0.73
0.92
Summary
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Aqueous methylmercury concentration
apparently strong predictor for body burden in
aquatic biota
Summary
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Aqueous methylmercury concentration
apparently strong predictor for body burden in
aquatic biota
Bioavailability of methylmercury tightly linked to
both quantity and quality of dissolved organic
carbon
Summary



Aqueous methylmercury concentration
apparently strong predictor for body burden in
aquatic biota
Bioavailability of methylmercury tightly linked to
both quantity and quality of dissolved organic
carbon
Efficiency of trophic transfer similar across most
sites
Summary

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Aqueous methylmercury concentration
apparently strong predictor for body burden in
aquatic biota
Bioavailability of methylmercury tightly linked to
both quantity and quality of dissolved organic
carbon
Efficiency of trophic transfer similar across most
sites
Body burden of mercury in top predators
controlled primarily by amount of bioavailable
methylmercury
Summary

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Aqueous methylmercury concentration
apparently strong predictor for body burden in
aquatic biota
Bioavailability of methylmercury tightly linked to
both quantity and quality of dissolved organic
carbon
Efficiency of trophic transfer similar across most
sites
Body burden of mercury in top predators
controlled primarily by amount of bioavailable
methylmercury
BAFs not sensitive to local/regional differences
in Hg body burdens of top predator fish
Acknowledgments
Mark Brigham, USGS, NAWQA
Dave Krabbenhoft, USGS, Toxics Program
George Aiken, USGS, National Research Program
Dennis Wentz, USGS, NAWQA
Michelle Lutz, USGS, Wisconsin Water Science Center
Mark Olson, USGS, Wisconsin District Mercury Laboratory
John DeWild, USGS, Wisconsin District Mercury Laboratory
Shane Olund, USGS, Wisconsin District Mercury Laboratory
Jeremy Pyatskowit, Menominee Indian Tribe of Wisconsin
Mitchell Harris, USGS, Illinois Water Science Center
Suwannee River Water Management District (FL)
St. Johns River Water Mangaement District (FL)
Florida Dept. of Environmental Protection
Florida Fish and Wildlife Conservation Commission
Wisconsin Department of Natural Resources
H. J. Andrews Experimental Forest, Oregon
Hg in Biota
0.5
Hg (g/g DRY weight)
Other
Crayfish
Grass Shrimp
0.4
0.3
0.2
0.1
0
M
St
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ar
s
ta
n
Sa
Fe
L
W
a
iv
k
e
ke
Pi
en
e
r
rg
e
Ev
O
ak
o
Lo
ut
o
k
Be
rt
e
av
on
Total Mercury in Invertebrates is
largely Methylmercury
MeHg (ng/g, dry)
800
y = 0.99x - 0.61
R2 = 0.92
600
400
200
0
0
200
400
THg (ng/g, dry)
600
800
Log10BAF for each Trophic Category
Florida
Little
Wekiva
Santa
Fe
Oregon
St.
Mary’s
Wisconsin
Beaverton
Lookout
Evergreen
5.30
4.53
5.55
5.11 5.04
Oak
Pike
Periphyton
Rock
Wood
5.05
4.22
4.19
Sediment
5.18
5.65
4.63
5.25
5.16
5.89
5.44 5.01
Invertebrates
5.99
6.10
5.59
6.16
5.34
6.29
5.82 5.82
Forage Fish
6.71
6.61
6.27
6.80
6.21
6.76
6.48 6.63
Predator Fish
7.48
7.31
7.25
7.02
6.68
7.03
6.86 6.73
Small variations in log10BAF can lead to
significant variations in predicted tissue
Hg concentrations
Florida
Oregon
Wisconsin
BAF
Trophic
Category
Little
Wekiva
Santa
Fe
St.
Mary’s
Beaverton
Lookout
Evergreen
Predator Fish
7.48
7.31
7.25
7.02
6.68
7.03
6.86 6.73
0.57
0.26
0.58
0.40 0.30
Oak
Pike
Tissue Hg
Site
Average
FMeHg
1.65
1.12
0.98