8019 - Laserfiche WebLink

Home Browse Search

Chironomidae (Midges) All were significantly different Other Diptera None were significantly different Other Invertebrates Dunn vs Pipe, Pipe vs Fisher These comparisons indicate: 1) densities of mayflies become comparable to those in Fisher River between Elkhorn and Pipe creeks; 2) caddisflies approach Fisher River densities between Dunn Creek and Elkhorn; and 3) stonefly densities do not approach Fisher River levels wit~'~ the Kootenai River study area. Midge densities differ both between rc~ulated sites and between regulated and control sites, while other dipterans and other invertebrate densities were not significantly different. An ANOVA test was also run on percent composition by biomass. Biomass showed the same trends as density by insect order, but with fewer differences that were significant for the mayflies, stoneflies, caddisflies and midges. Other Diptera and Other Invertebrates were combined for volumetric analyses and showed significant biomass differences between the control and regulated sites. The comparisons that were significantly different (P<O.05) are listed below. Order Paired Sampling Sites Dunn vs Pipe, Dunn vs Fisher Dunn vs Fisher, Elkhorn vs Fi sher, Pipe vs Fisher Dunn vs Elkhorn, Dunn vs Pipe, Dunn vs Fisher Dunn vs Elkhorn, Dunn vs Pipe, Dunn vs Fisher, Elkhorn vs Fisher, Pipe vs Fisher Dunn vs Fisher, Elkhorn vs Fisher, Pipe vs F i she r Dunn vs Fisher, Elkhorn vs Fisher, Pipe vs Fisher Ephemeroptera (Mayflies) Plecoptera (Stoneflies) Trichoptera (Caddisflies) Chironomidae (Midges) Other Diptera Other Invertebrates Comparisons of Pre- and Post-Impoundment Densities and Biomass Overall, post-impoundment densities were an order of a magnitude higher than those found at the Dunn Creek site in pre-impoundment studies (Table 6). This is due in part to the fact that some of our samples were taken with the kick sampler which collects many more of the small instars than the Knapp-Waters sampler used in pre-impoundment studies. Also, there is not a direct month-to-month correspondence in the sampling dates which could lead to differences. It does seem evident, however, that higher numbers of a few species of mayflies and dipterans projected -10-