HOW DO FINE SEDIMENTS AND HANGMAN CREEK DISCHARGE AFFECT BENTHIC MACROINVERTEBRATES IN THE SPOKANE RIVER?
One of the most common causes of stream degradation globally is fine sediment deposition. Hangman Creek is a major tributary and source of fine sediment to the Spokane River (Washington, USA). The objective of this study is to investigate the effects of fine sediments on Spokane River macroinvertebrates. We sampled macroinvertebrate communities from 3 substrate types with different levels of fine sediment (sand, 0 - 25% embedded cobbles, and 75-100 % embedded cobbles) in the Spokane River upstream and downstream of its confluence with Hangman Creek and in Hangman Creek itself. The most three common invertebrates in the Spokane River were Chironomidae, Baetis, and Hydropsyche. To determine effects of sediment and Hangman Creek discharge on macroinvertebrate metrics we performed two-way ANOVAs with site and substrate type as independent variables. In early summer 2018, substrate significantly affected density of macroinvertebrates; family richness for Ephemeroptera, Plecoptera, and Trichoptera (EPT); proportion EPT; proportion Clinger functional group; and the proportion of the dominant taxon. Family richness for all taxa and Shannon-Weaver diversity were not affected. This work will contribute to our understanding of the biotic effects of these sediments.
Anwar Bushnaq (Primary Presenter/Author), Eastern Washington University , email@example.com;