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Food webs and contaminantsImplications for NRDAR at the
land-water interface
Johanna M. Kraus, Ph.D.US Geological Survey, Fort Collins CO
• Aim: Broaden the discussion about natural resource injuries and restoration in linked freshwater-terrestrial ecosystems from a food web perspective.
How do we think about damage?
Baxter et al. 2005
Freshwater-Terrestrial Linkages
Consequences of aquatic stressors
http://cdn.audubon.org www.nps.gov
1. Indirect impact of contaminants on fish mitigated by terrestrial invertebrate subsidies.
2. Cascading or “ripple” effects of aquatic contaminants on terrestrial consumers (spiders, birds, bats etc.)
3. Predicting when you might have a food loss problem, an exposure problem, both or neither.
Take Homes
1. Indirect impact of contaminants on fish mitigated by terrestrial invertebrate subsidies.
2. Cascading or “ripple” effects of aquatic stressors on terrestrial consumers (spiders, birds, bats etc.)
3. Predicting when you might have a food loss problem, an exposure problem, both or neither.
Take Homes
How do stream metals affect use of terrestrial resources by fish?
Kraus et al. 2016, JAE
A.
Terr
estr
ial/A
quat
icIn
sect
Bio
mas
s%
Sto
mac
h C
onte
nts
0
20
40
60
80 B.
1.0 100.1
R2 = 0.46, 0.99b
P = 0.016b
R2 = 0.49, 0.84b
P = 0.007b
Stream Metal (CCAR)
% F
ish
Eatin
g Te
rres
tria
l
0
20
40
60
80
100C.
R2 = 0.19P = 0.037
4.0
2.3
1.0
0.3
0.0
10% of insect biomass in diet
Metal: Low
Stream Trout Diet
Kraus et al. 2016, JAE
A.
Terr
estr
ial/A
quat
icIn
sect
Bio
mas
s%
Sto
mac
h C
onte
nts
0
20
40
60
80 B.
1.0 100.1
R2 = 0.46, 0.99b
P = 0.016b
R2 = 0.49, 0.84b
P = 0.007b
Stream Metal (CCAR)
% F
ish
Eatin
g Te
rres
tria
l
0
20
40
60
80
100C.
R2 = 0.19P = 0.037
4.0
2.3
1.0
0.3
0.0Metal: Moderate
54% of insect biomass in diet
More metals = more terrestrial subsidies
Stream Trout Diet
Kraus et al. 2016, JAE
Compensatory?
Stream Trout Density and Condition
Kraus et al. 2016, JAE
• Aquatic and riparian food webs may become more terrestrial as aquatic stressors increase.
Aquatic dominates
Terrestrial dominates
Stream metal (CCAR)
Prey
bio
mas
s
Terrestrial prey
Basis of Production
1. Indirect impact of contaminants on fish mitigated by terrestrial invertebrate subsidies.
2. Cascading or “ripple” effects of aquatic stressors on terrestrial consumers (spiders, birds, bats etc.)
3. Predicting when you might have a food loss problem, an exposure problem, both or neither.
Take Homes
1. Indirect impact of contaminants on fish mitigated by terrestrial invertebrate subsidies.
2. Cascading or “ripple” effects of aquatic stressors on terrestrial consumers (spiders, birds, bats etc.)
3. Predicting when you might have a food loss problem, an exposure problem, both or neither.
Take Homes
Intro to system slide
Schmidt et al. 2010, 2011, 2012Kraus et al. 2014, Eco Apps
Emergence Production
Kraus et al. 2014, Eco Apps
97% loss
Emer
genc
e (m
g dr
y m
ass/
trap
/d)
Trace metals
Aquatic diptera flux (mg m-1d-1)
0 2 4 6 8 10 12
(a)
(b)
Den
sity
(m-2)
Biom
ass
(mg
m-2)
0.1
0.3
1
0.1
1
10
P = 0.02R2 = 0.20Block*
P = 0.04R2 = 0.29Block*
Web-building spiders
Kraus et al. 2014 Eco Apps
75% decline in spider biomass
Trace metals
Low metal High metal
X =
Metal Accumulation and Flux
Kraus et al. 2017 ET&C
“Contaminant vector”
Lipid-corrected PCB concentrations up to
~10,000 ng/g
Web-building spiders: PCBs
Current-use Pesticides
Adult aquatic insects: Pesticides
Kraus et al. In prep
• Intense agriculture• Critical habitat for water fowl• Insectivorous bird declines
1. Indirect impact of contaminants on fish mitigated by terrestrial invertebrate subsidies.
2. Cascading or “ripple” effects of aquatic stressors on terrestrial consumers (spiders, birds, bats etc.)
3. Predicting when you might have a food loss problem, an exposure problem, both or neither.
Take Homes
1. Indirect impact of contaminants on fish mitigated by terrestrial invertebrate subsidies.
2. Cascading or “ripple” effects of aquatic stressors on terrestrial consumers (spiders, birds, bats etc.)
3. Predicting when you might have a food loss problem, an exposure problem, both or neither.
Take Homes
ContaminantEcosystem
CommunityIndividuals
Habitat
Framework for Predicting Effects
Kraus et al. 2014 ES&T
Framework for Predicting Effects
Framework for Predicting Effects
Kopp and Allen, U OklahomaColin Talbert, USGS
Framework for Predicting Effects
1. Indirect impact of contaminants on fish mitigated by terrestrial invertebrate subsidies.
2. Cascading or “ripple” effects of aquatic stressors on terrestrial consumers (spiders, birds, bats etc.)
3. Predicting when you might have a food loss problem, an exposure problem, both or neither.
Take Homes
• Aim: Broaden the discussion about natural resource injuries and restoration in linked freshwater-terrestrial ecosystems from a food web perspective.
How do we think about damage?
Johanna M. Kraus, Ph.D.US Geological Survey, Fort Collins CO
Food webs and contaminantsImplications for NRDAR at the
land-water interface
