1 / 19

What caused a regime shift in the Wabash River? Indiana AFS Feb 28, 2014

What caused a regime shift in the Wabash River? Indiana AFS Feb 28, 2014. Mark Pyron, Jesse Becker, Dawn DeColibus, Kevin Wyatt, and Allison Rober Center of Aquatic Biology and Fisheries Environmental Science. Previous results: regime shift. Regress body size on size bins

claudio-crowe
Download Presentation

What caused a regime shift in the Wabash River? Indiana AFS Feb 28, 2014

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. What caused a regime shift in the Wabash River?Indiana AFSFeb 28, 2014 Mark Pyron, Jesse Becker, Dawn DeColibus, Kevin Wyatt, and Allison Rober Center of Aquatic Biology and Fisheries Environmental Science

  2. Previous results: regime shift Regress body size on size bins Negative slope = inefficient transfer

  3. Wabash River Regime Shift Body size distribution of fishes changed: 1974-2008

  4. Abundances in trophic groups

  5. Potential causes of regime shift? Large flood / severe drought Point-source pollution Over-harvesting fish Excess nutrients, increased algae, diet change in upper trophic levels

  6. Diet of fishes change?Pilot analysis • Isotope analyses: 13C and 15N ratios Museum archives 1960-2008 Predator = spotted bass, drum, sucker Omnivores = spotfinshiner Detritivore = gizzard shad

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

  8. INHS archival fishes: Wabash River

  9. Gizzard shad now consume additional sources NANFA.ORG

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

  11. Upstream individuals consume at lower trophic levels

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

  13. Has diet changed? STOMACH CONTENTS Gizzard shad

  14. Summary Fish diets changed 1960-2000 Gizzard shad consume less algae, low quality Algal assemblage changed – cause?

  15. Summary • Fish diet changed • Algal assemblage changed • Asian carp / Higher nutrients?

More Related