Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for...
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![Page 1: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/1.jpg)
Ecological Interactions
in Lake Superior
Sean Cox, Chris Harvey, and Jim Kitchell
Center for Limnology
University of Wisconsin, Madison
![Page 2: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/2.jpg)
Fish community objectives (FCOs)
• Self-sustaining forage fish
populations
• Maintaining native fish
community
• Self-sustaining lake trout
populations
• Self-sustaining populations of
salmon
![Page 3: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/3.jpg)
Outline
• Lake Superior food web structure: Stable Isotopes
• Simulating ecological and fishery interactions: 1929-1998
• Recommendations
![Page 4: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/4.jpg)
PhytoplanktonDetritus
ZooplanktonDiporeia
HerringS. sculpin
L.T.SiscowetBurbot
D. sculpin Chub Whitefish
Mysis
Lake Superiorpelagic food web
(ancestral)
Tro
ph
ic L
evel
2
4
5
3
![Page 5: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/5.jpg)
PhytoplanktonDetritus
ZooplanktonDiporeia
HerringS. sculpin
L.T.SiscowetBurbot
SteelheadCohoChinook
SmeltD. sculpin Chub Whitefish
Mysis
Sea lampreyLake Superior
pelagic food web(modern)
Tro
ph
ic L
evel
2
4
5
3
![Page 6: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/6.jpg)
• Heavy to light isotope ratio in tissues
15N/14N and 13C/12C
• Fractionate predictably up food chain
What are they?
Trophic structure: Stable Isotopes
![Page 7: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/7.jpg)
• Tracers of long-term diet history
• 15N indicates trophic level
• 13C indicates production source
What are they used for?
Trophic structure: Stable Isotopes
![Page 8: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/8.jpg)
15N
(‰
)
Tro
ph
ic level
13C (‰) Production source
0
3
7
-30 -26 -22 -18
10
Phytoplankton
Zooplankton
Forage fish
Top predator
Trophic structure: Stable Isotopes
![Page 9: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/9.jpg)
15N
(‰
)
Tro
ph
ic level
13C (‰) Production source
Coho
Cladocerans
Cycl. Copepods
Diporeia
Kiyi
Cal. Copepods
Bloater
Seston
Dws
LeanBurbotSiscowet
Chinook
Mysis
Smelt
HerringS. Sculpin
0
2
4
6
8
10
12
-32 -30 -28 -26 -24
DeepFood Web
Shallow Food Web
Trophic structure: Western L. Superior
![Page 10: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/10.jpg)
The “real” top predator: Sea lamprey
![Page 11: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/11.jpg)
15N
(‰
)
Tro
ph
ic level
Lamprey body mass (grams)
0
2
4
6
8
10
12
14
16
0 100 200 300 400
Transformers
Parasites
Spawners
Lake herring diet only
Isotopes indicate diet changes
![Page 12: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/12.jpg)
Simulating ecological interactions
![Page 13: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/13.jpg)
Simulating ecological interactions
Fishery Catch - Catch - Effort
USGS Trawl Survey - Biomass - Recruitment
Exotic Invasion - Smelt - Sea lamprey
Food Web Structure - Stable isotopes - Food habits
Stock Assessment - Biomass - Recruitment - Harvest rates
Ecosystem Simulation Model
Species Interactions - Competition - Predation
Fishery Interactions
![Page 14: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/14.jpg)
Changes in major species since 1930B
iom
ass /
Bio
mass in
1930
0
1
2
3
4
LakeHerring
Chub Whitefish LakeTrout
Siscowet
1950s 1990s
![Page 15: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/15.jpg)
Deep water food web
0
1
2
3
4
1930 1940 1950 1960 1970 1980 1990 2000
0
1
2
1930 1940 1950 1960 1970 1980 1990 2000
Chub
Siscowet
Bio
mass /
Bio
mass 1
930
![Page 16: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/16.jpg)
Deep water food webB
iom
ass /
Bio
mass 1
930
![Page 17: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/17.jpg)
Shallow water food webB
iom
ass /
Bio
mass 1
930
![Page 18: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/18.jpg)
Key Ecological Effects
• Potentially important interaction
between whitefish and herring
• Mysis and smelt facilitate energy
transfer between deep and shallow food
webs
• System continues to respond to
invasion and collapses that occurred
more than 50yrs ago
![Page 19: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/19.jpg)
Recommendations
• Develop management plan aimed
specifically
at recovery of lake herring
• Siscowet too, but magnitude is
uncertain
• Whitefish may be headed for moderate
decline as they approach carrying
capacity
![Page 20: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/20.jpg)
Compensatory recruitment
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0.0 0.5 1.0 1.5
Spawning stock
Ag
e-1
Recru
itm
en
t
![Page 21: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/21.jpg)
Lake herring recruitment, 1929-1970
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0.0 0.5 1.0 1.5
Spawning stock
Ag
e-1
Recru
itm
en
t
![Page 22: Ecological Interactions in Lake Superior Sean Cox, Chris Harvey, and Jim Kitchell Center for Limnology University of Wisconsin, Madison.](https://reader035.fdocuments.in/reader035/viewer/2022062423/56649e105503460f94afbf99/html5/thumbnails/22.jpg)
Depensatory recruitment
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0.0 0.5 1.0 1.5
Spawning stock
Ag
e-1
Recru
itm
en
t
1971-1998