Impact of variation in light intensity on habitat preference of macroinvertebrates in Carp Creek.

Abstract

Freshwater ecosystems are key contributors to global levels of biodiversity. Though small in area, these regions contain greater numbers of endemic species than all marine ecosystems combined (Angelier 2003). This species richness is especially influenced by invertebrate insect populations. The taxonomic composition of these ecosystems is a product of certain abiotic factors: water velocity, water chemistry, substrate, and amount of sunlight (Cushing & Allan 2001). Of these, sunlight has been investigated the least. In this study we address how the patchiness of sunlight in a stream affects the distribution and abundance of macroinvertebrates. In Carp Creek near Pellston, Michigan, invertebrate communities were compared between both sunlit and shaded sites. We found that the majority of identified taxa did not prefer sun or shade, though three of the 17 taxa (Amphipoda, Ephemeroptera, Diptera) were significantly more abundant at sunny sites. We conclude by discussing the relevance of our findings for conservation strategies that attempt to maximize stream macroinvertebrate diversity.