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Wednesday, May 28, 2008 - 2:00 PM
436
(TALK WITHDRAWN BY SPEAKER) the effects of storm events on the behavior of hydropsychid net-spinning caddisflies
Thomas A. Sobat, Life Sciences, Ivy Tech State College of Indiana, 4301 S. Cowan Rd., Muncie, IN 47302 and Gary Dodson, Biology, Ball State University, Muncie, IN 47302.
Physical disturbance in the form of storm events has been implicated as a major determinant of community structure in streams. But there has been limited study of this effect on individual taxa within the communities. Such work is necessitated by untested assumptions regarding the behavior of bioindicator species in these systems. If a species is recorded as absent from samples when it is present but hidden, the resultant false negative would bias water quality assessment. I tested hypotheses regarding the behavior of hydropsychid caddisflies facing increased discharge, and the effect of stream size on this phenomenon.
Three sites along the West Fork of the White River, Indiana USA were studied during nine storms between 2001 and 2004. Stratified sampling from the upper 15 cm of substrate revealed alterations of hydropsychid distributions. During storms hydropsychids sought refuge in the hyporheic zone at depths dependent upon storm intensity. The possibility that poor water quality resulting from increased discharge caused the hydropsychid behavior was refuted by chemical analysis. Family level biotic index (FBI) data demonstrated that increased discharge results in reduced stream FBI values. These results indicate that high intensity storm events influence biological monitoring and should be factored into sampling protocol.
Web Page: storm events, caddisflies, disturbance
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See more of The Nabs 56th Annual Meeting (25-28 May, 2008)
See more of Contributed Sessions
See more of The Nabs 56th Annual Meeting (25-28 May, 2008)