Wednesday, May 28, 2008 - 10:15 AM
383

Downstream impacts of recreational releases from abanakee dam on organic matter transport and macroinvertebrate drift

Randy Fuller1, Jaime Dennison1, Gretchen Swarr1, Kelly Weichert1, Carrie Griego1, and Martin W. Doyle2. (1) Biology Department, Colgate University, Hamilton, NY 13346, (2) Department of Geography, University of North Carolina- Chapel Hill, CB 3220, Chapel Hill, NC 27599

We measured macroinvertebrate drift and organic matter transport at four sites below Abanakee Dam at base flow and during a release.  The Indian River experiences recreational releases 4 days/week (for 2.5 h/day) from April to October; the releases increase discharge from ~300 cfs at base flow to ~1600 cfs simulating a bank-full flooding event.  Transport of both FPOM and CPOM were similar at all 4 sites under base flow conditions; however during a release, both FPOM and CPOM increased with distance from the dam.  The river has three geomorphic regions with higher gradients near the dam (within 0.5 km) and at the downstream reaches (>4 km) and a lower gradient in the mid-regions (~3 km from dam).  In the mid-region, both CPOM and FPOM transport did not increase from what we observed at the upstream site whereas the most downstream site had the highest CPOM and FPOM in transport.  Thus, transport did increase with distance from the dam, but it appears that river geomorphology played a role in transport dynamics.  Preliminary results from macroinvertebrate drift samples suggest highest drift rates occurred near the dam and were largely due to high numbers of Simuliidae in the drift at this site.


Web Page: Organic matter transport, Macroinvertebrate drift, Floods

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