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Long-term variation in the Wabash River ecosystem The Wabash River Workshop IUPUI Dec 13, 2013

Long-term variation in the Wabash River ecosystem The Wabash River Workshop IUPUI Dec 13, 2013. Mark Pyron Center of Aquatic Biology and Fisheries Environmental Science. Background Side scan sonar Long term fish assemblage Size spectral analysis Isotope analyses. Wabash River.

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Long-term variation in the Wabash River ecosystem The Wabash River Workshop IUPUI Dec 13, 2013

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  1. Long-term variation in the Wabash River ecosystemThe Wabash River WorkshopIUPUI Dec 13, 2013 Mark Pyron Center of Aquatic Biology and Fisheries Environmental Science

  2. Background • Side scan sonar • Long term fish assemblage • Size spectral analysis • Isotope analyses

  3. Wabash River • 2nd largest trib of Ohio River • 85,000 km2 watershed • 764 km long

  4. Upstream Wabash River: medium-sized river with gravel substrates

  5. Inner bends have sandy beaches

  6. Downstream: large river; some vegetated riparian buffer

  7. and flat meanders

  8. 1. Fish data James Gammon 1974-98 Mark Pyron 2000-8 230 km

  9. Jim Gammon began project 1974-98 500-m sites Boat electrofishing

  10. Sampling Protocol: • Electrofish 500 m • Collect all fishes • Measure, release

  11. Fish assemblage patterns • Major gradient = river distance: substrate and habitat variation • Species separate along gradients

  12. Upstream: riffles, pools, gravel-cobble Blue sucker River redhorse

  13. Shovelnose sturgeon Everywhere = Freshwater drum

  14. Downstream: runs, sand-silt Flathead catfish Bigmouth buffalo

  15. Grass carp

  16. Asian carp

  17. Sauger Longnose gar

  18. GIS Approach to Analysis of Fish Assemblages Using Bathymetry, Water Velocity, Sediment and Woody Debris Mark Pyron, Reuben Goforth, Jayson Beugly, Scott Morlock, Moon Kim

  19. Sample 1: June 2009 Acoustic Doppler Current Profiler Interfaced with Differential Global Positioning System receiver 10-km reach at Lafayette, Indiana

  20. Three boats collect fishes: Ball State, Purdue, IDNR • Left, Center, Right bank • Individual fish assigned lat-long GPS coordinate

  21. Majority of fishes along banksBlue suckerCarpsuckerFreshwater drum

  22. CCA 4 x 4 m

  23. CCA 10 x 10 m

  24. CCA 30 x 30 m

  25. Summer 2012 • Sidescan sonar map; most of Wabash River • Collect fishes at four locations • Predict assemblages for entire river

  26. Highest abundances?

  27. CCA: species and environmental variables MEAN DEPTH Gravel

  28. Long term fish assemblage • Size spectral analysis • Time lag ordination • Isotope analyses

  29. Size spectral analysis: examine organisms by size Convert size-abundance matrix into size bins Regress abundances against size bins

  30. Examine organisms by size Convert size-abundance matrix into size bins Regress abundances against size bins Steeper with exploitation Steep regression = inefficient ecological transfer

  31. Spectral analysis • Use only individuals > 162 mm SL • (susceptible to boat electrofisher) • Regime shift in 1990s?

  32. steep regression = inefficient ecological transfer 1974-94 1994-1999 1999-2008

  33. 1974-2008 Trophic Groups

  34. Diet of fishes change?Pilot analysis • Isotope analyses: 13C and 15N ratios Museum archives 1960-2008 Detritivore = gizzard shad Omnivore = spotfin shiner Piscivore = spotted bass

  35. One trophic level ~ 3 ppt d15N Algae Macrophytes http://sofia.usgs.gov

  36. INHS archival fishes: Wabash River

  37. Gizzard shad consume additional sources NANFA.ORG

  38. Gizzard shad consume additional sources • Shiner consume lower trophic sources NANFA.ORG

  39. Individuals consume lower trophic levels in upstream locations

  40. Diet of consumer fishes (planktivore / omnivore) in 1990s Different algae? Different nutrients? Impact of Asian carp? Isotope RESULTS

  41. Summary • Switch in functional group dominance • Omnivores + planktivores to benthivores • Asian carp cause change in food web?

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