Tuesday, May 27, 2008
235

Effects of recreational flow releases on macroinvertebrate communities of the indian and hudson rivers in the adirondack mountains, new york

Barry P. Baldigo, New York Water Science Center, US Geological Survey, 425 Jordan Road, Troy, NY 12180 and Alexander J. Smith, Stream Biomonitoring Unit, New York State Department of Environmental Conservation, 425 Jordan Road, Troy, NY 12180.

The effects that recreational flow releases (4 times weekly) from a small impoundment had on macroinvertebrates in headwaters of the Indian and Hudson Rivers during 2006 were assessed by comparing community indices, feeding guilds, dominant species, and Bray–Curtis similarities at three affected Indian River sites (below the impoundment) with those indices at four Cedar River control sites (below a comparable, but run-of-the-river impoundment) and through another comparison of the indices at four less severely affected Hudson sites with those at an upstream control site. All analyses identified strong impoundment effects at Indian (IR01) and Cedar (CR01) sites just below respective dams (as expected), moderate effects at two Indian sites 2.2 to 3.9 km downstream, and minor or no effects at Cedar sites 8.0 to 53.5 km downstream or at any Hudson River site. Bray–Curtis similarities indicate that macroinvertebrate assemblages did not differ significantly (P < 0.05) among sites within each impact class. The paucity of scrapers at all Indian River sites, and the predominance of Simulium gouldingi  and Pisidium compressum only at IR01, identify minor differences in feeding guilds and dominant species between sites IR01 and CR01, which indicates that recreational flow releases have a small, localized impact on macroinvertebrate communities in the Indian River.


Web Page: flow regulation, impoundment effects, macoinvertebrates

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