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Photo by Rob Criswell, from the Pennsylvania Department of Conservation and Natural Resources web site (http://www.dcnr.state.pa.us/wrcf/chdart.htm). Characteristics of Channel Darter Habitat in the Winooski River, Vermont. Douglas E. Facey and Shannon M. O ‘Brien Department of Biology
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Conservation and Natural Resources web site
Douglas E. Facey and Shannon M. O ‘Brien
Department of Biology
Saint Michael’s College
Channel darters (Percina copelandi) are found in the southern, central, and northeastern United States and southeastern Canada, but their populations are often highly localized and have declined dramatically in some areas. This decline is believed to be the result of habitat degradation due to sedimentation. In Vermont, channel darters have been found in only three Lake Champlain tributaries. The species was first reported in the Winooski River in 1996, and only a few individuals had been captured prior to 2002. Channel darters also are rare in the Poultney River, and only three have been found in the LaPlatte River. Therefore, little is known of their distribution and habitat use in this part of their range. Forty-four channel darters were captured during a study in the Winooski River in summer of 2002. Sampling was done in 3 X 10 m plots, and water depth, surface velocity, and substrate samples were taken at each plot. Channel darters were caught in six of 56 plots, but 24 of the 44 channel darters caught were from one plot. Sample plots with channel darters had substrate that averaged (by weight) over 60% particles over 1.9 mm in size, and less than 7% particles under 0.23 mm.
The Winooski River flows into Lake Champlain just north of Burlington, Vermont. Lake Champlain flows northward into the Richelieu River, which empties into the St. Lawrence River near Montreal.
Calculated Chi Square to determine if channel darters were randomly distributed – used Poisson distribution to determine expectation
Chi square = 43.7; df = 1; P<0.00001
Conclusion – channel darters were not randomly distributed among the plots sampled
Table 2. Mean percent substrate composition (+SD) of plots sampled.Note that plots with channel darters had less fine substrate (<0.54 mm) and more coarse substrate (>1.9 mm) than plots with no channel darters.