Impacts of a Small Dam on Riverine Zooplankton

In order to explore the temporal impacts of a small dam on riverine zooplankton, monthly samples were conducted from November 2005 to June 2006 in a reach of Xiangxi River, China, which is affected by a small hydropower plant. A total of 56 taxa of zooplankton were recorded during the study and rotifers were the most abundant group, accounting for 97% of total taxa, while the others were copepod nauplii and copepod adults. This study indicated that: (1) the small dam in the Xiangxi River study area created distinct physical and ecological conditions relative to free‐flowing lotic reaches despite the constrained channel and small size of the dam; (2) the existence of the plant's small dam had a significant effect on the zooplankton community. In long periods of drought or dry seasons the effect of the dam on potamoplankton was more pronounced ( e.g ., November, February, March, and May). But the downfall or the connectivity of channel appeared to decrease the effect of small hydropower plants on riverine zooplankton ( e.g ., April). The present observation underscores the need for additional studies that provide more basic data on riverine zooplankton communities and quantify ecological responses to dam construction over longer time spans. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)