Regime Change in a Large River Fish Assemblage Mark Pyron Center of Aquatic Biology and Fisheries...
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Regime Change in a Large River Fish Assemblage
Mark PyronCenter of Aquatic Biology and FisheriesEnvironmental Science
Purdue Chapter of IN AFS
Collaborators:
Topics
• Wabash River
• Body size analysis– Change with time
• Food web analysis
Wabash River•2nd largest trib of Ohio River
•85,000 km2 watershed
•764 km long
History of Wabash River• -1900: Abundant and diverse fishes
History of Wabash River
• pre-1900: Abundant and diverse fishes
• 1900 – 1974: point source pollution, agriculture, dam building
History of Wabash River
• pre-1900: Abundant and diverse fishes
• 1900 – 1974: point source pollution, agriculture, dam building
• 1974: Clean Water Act
History of Wabash River
• pre-1900: Abundant and diverse fishes
• 1900 – 1974: point source pollution, agriculture, dam building
• 1974: Clean Water Act
• 1974 – 2015: invasive species, nutrient and sediment reduction
Carroll
Tippecanoe
Warren
Fountain
ParkeV
erm
illio
n
Vigo
Sullivan
Terre Haute
Clinton
10 km
Indiana
N
Fish work:Jim Gammon collected 1968-98
Lauer & Pyron 2001-8
Jim Gammon began project 1968-98
•500-m sites
•Boat electrofishing
Sampling Protocol:
• Electrofish 500 m
• Collect all fishes
• Measure, release
Sampling Protocol:
Gammon’s results:
• High diversity: 100+ species
• Recovering from pollution• IBI scores improved
Longterm assemblage: body size analysis
• Convert size-abundance matrix into size bins• Regress abundances against size bins
Examine organisms by size
• Convert size-abundance matrix into size bins• Regress abundances against size bins• Steeper with exploitation• Steep regression = inefficient ecological transfer
Longterm assemblage:
• Steeper with exploitation 1974-93
1974-931994-2008
-4.5
-4
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
1970 1975 1980 1985 1990 1995 2000 2005 2010
Size
-Spe
ctra
Slop
eSize spectra slope:
Proxy for ecological (transfer) efficiency
Trophic Groups
Planktivores
fishofohio.com
Gizzard Shad miseagrant.umich.edu
Silver Carp
Benthic invertivores
tnfish.org
ohiodnr.gov
Trophic Groups
Freshwater Drum
Shorthead Redhorse
Blue Sucker
Planktivores
fishofohio.comGizzard Shad
miseagrant.umich.edu
Silver Carp
Benthic invertivores
tnfish.org
ohiodnr.gov
Trophic Groups
Freshwater Drum
Shorthead Redhorse
Blue Sucker
Piscivores
Spotted Bassohiodnr.gov Longnose Gar
tpwd.texas.gov
Planktivores Gizzard Shad
fishofohio.com
Changes in Trophic Groups
Community shift ~ 1992
• Persistent change in structure and function of a system
• Cause?
• Nutrients, invasive species, hydrologic alterations, climate change?
Time lag analysis: 1968-2008
• Use only individuals > 162 mm SL• (susceptible to boat electrofisher)
• Was there a large change in fish assemblages in mid-90s?
-0.6 1.0
-1.0
1.0
1968
1969
19701971
1972
1973 1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
19861987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
2001
2002 2003
2004
2005
2006
2007
2008
Redundancy Analysis
Change in assemblage?
Species that drive RDA
-0.8 1.0
-0.6
0.8
AmercEel
BighCarp
BigmBuff
BlacBuff
BlacBull
BlacCrap
BlacRedh
BlueCatf
BlueSuckBluegill
BowfinBurbot
ChanCatf
ChesLamp
CommCarp
FlatCatf
FresDrum
GizzShad
GoldRedhGoldeye
Goldfish
GrasCarp
GrasPick
GreaRedh
GreeSunfHighCarp
LargBass
LongSunf
LongnGar
MooneyeNortHogs
PaddleFs
QuilCarpRedeSunf
RivrCarp
RivrChub
RivrRedhRockBass
Sauger
ShorRedh
ShortGar
ShovStur
SilvCarp
SilvLamp
SilvRedhSkipHerr SmalBass
SmalBuff
SpotBass
SpottGar
SpotSuck
Walleye
WhitBass
WhitCrapWhitSuck
YellBass
YellBull
AmBrooLm
-0.6 1.0
-1.0
1.0
1968
1969
19701971
1972
1973 1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
19861987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
2001
2002 2003
2004
2005
2006
2007
2008
Food Web Analysis
• Isotopes: 13C and 15N ratiosMuseum archives
Pre-1992 vs Post -1992
–Piscivores–Benthic invertivores–Planktivores
• Mussels• Fishes
Food web analysis:
sofia.usgs.gov
-25.0-25.8-26.6-27.4-28.2-29.0-29.8
18
17
16
15
14
13
12
Mean d15C ratio
Mea
n d1
3N r
atio
Pre 1992Post 1992
Benthic Invertivores
Benthic Invertivores
Planktivore/Omnivore
Planktivore/Omnivore
Silver Carp
Planktivore / Detritivore
MusselsMussels
Silver Carp consume pelagic detritus
miseagrant.umich.edu
Mean d13C
Mea
n d1
5N
-25.0-25.8-26.6-27.4-28.2-29.0-29.8
18
17
16
15
14
13
12
Mean d15C ratio
Mea
n d1
3N r
atio
Pre 1992Post 1992
Benthic Invertivores
Benthic Invertivores
Planktivore/Omnivore
Planktivore/Omnivore
Silver Carp
Planktivore / Detritivore
MusselsMussels
Mussels shifted sourcesM
ean
d15N
-25.0-25.8-26.6-27.4-28.2-29.0-29.8
18
17
16
15
14
13
12
Mean d15C ratio
Mea
n d1
3N r
atio
Pre 1992Post 1992
Benthic Invertivores
Benthic Invertivores
Planktivore/Omnivore
Planktivore/Omnivore
Silver Carp
Planktivore / Detritivore
MusselsMussels
Gizzard shad and Minnows
Mean d13C
-25.0-25.8-26.6-27.4-28.2-29.0-29.8
18
17
16
15
14
13
12
Mean d15C ratio
Mea
n d1
3N r
atio
Pre 1992Post 1992
Benthic Invertivores
Benthic Invertivores
ePlanktivore/Omnivor
Planktivore/Omnivore
Piscivore
Piscivore
Silver Carp
Planktivore / Detritivore
MusselsMussels
Complete assemblage
Mean d13C
Mea
n d1
5N
Algal assemblage changed(gizzard shad stomachs)
2014Water column
Food web changed from 1968-2008
• Shift from pelagic to benthic carbon sources• Causes?
• Changes in nutrients?
• Changes in algal assemblage; both?
1975 1980 1985 1990 1995 2000 2005 20100
0.5
1
1.5
2
2.5
3Daily Statistics for Organic N Concentrations
Year
Org
anic
N C
once
ntra
tion
(mg/
L)
Min
AvgStd
1975 1980 1985 1990 1995 2000 2005 20106
8
10
12
14
16
18
20
Year
Org
anic
N C
once
ntra
tion
(mg/
L)
Max
Food web changed from 1968-2008
• Decrease in N, Increase in P
• Correlated with increased benthic invertivores
Logsdon et al.
Silver Carp fecal pellets transfer nutrients to benthic fishes
• Blue catfish increased growth
• Channel catfish survive
Silver Carp fecal pellets transfer nutrients to benthic fishes
• Blue catfish increased growth
• Shift nutrient source from pelagic to benthic habitat
Plankton consumed by Silver Carp: fecal pellets available to other consumers
AlgaeAlgaeRiparian C3Riparian C3-25.0-25.8-26.6-27.4-28.2-29.0-29.8
18
17
16
15
14
13
12
Mean d15C ratio
Mea
n d1
3N r
atio
Pre 1992Post 1992
Benthic Invertivores
Benthic Invertivores
ePlanktivore/Omnivor
Planktivore/Omnivore
Piscivore
Piscivore
Silver Carp
Planktivore / Detritivore
MusselsMussels
SummarySummary
• Switch in trophic group dominanceSwitch in trophic group dominance• Planktivores to benthivoresPlanktivores to benthivores• Silver Carp and Ag nutrientsSilver Carp and Ag nutrients
• Food web changes: Food web changes: • Shift from pelagic to detritus Shift from pelagic to detritus