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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Life Histories
EFFECTS OF AN URBAN IMPOUNDMENT ON THE PRODUCTION OF CHEUMATOPSYCHE PETTITI AND HYDROPSYCHE BETTENI (TRICHOPTERA: HYDROPSYCHIDAE).
S.A. Ridout and L.A. Smock. Department of Biology, Virginia Commonwealth University, Richmond, Virginia 23284
The influence of the impoundment of a 2nd order stream on two species of net-spinning caddisflies in a highly urbanized watershed in central Virginia was investigated over one year. Life histories, abundance and secondary production were determined through sampling of Cheumatopsyche pettiti and Hydropsyche betteni, the only two hydropsychid species in the stream. Sampling was from riffles above and below the small impoundment. Life histories of both species were at least bivoltine, with autumn-spring and summer cohorts. C. pettiti was about 60 times more abundant than H. betteni both above and below the impoundment. The combined annual mean density and biomass of the two species above the impoundment were 2481 m-2 and 969 mg m-2, respectively, whereas they were 1140 m-2 and 331 mg m-2 below the impoundment. Annual production of C. pettiti was 6464 mg m-2 and 2454 mg m-2 above and below the impoundment, respectively, whereas production of H. betteni was 140 mg m-2 and 103 mg m-2. The urban impoundment, which receives runoff from residential, commercial and industrial areas, thus had a positive impact on the abundance and production of these two hydropsychid species.
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