Do Freshwater Macroinvertebrates Select for Different Substrates Used in Fisheries Habitat Enhancement?

Habitat enhancement projects are commonly used for augmenting fisheries in lakes and reservoirs, but a dearth of research exists regarding how habitat enhancements influence lower trophic levels. Structures used for habitat enhancement may be comprised of a range of natural and artificial materials and thus present different substrates for macroinvertebrates. We examined whether motile, grazing macroinvertebrates from the genera Baetis, Ischnura, Pachydiplax, and Trichocorixa exhibited different selection for substrates commonly used in fisheries habitat enhancement projects. Substrates evaluated included natural pine wood with bark, polyvinyl chloride plastic (PVC; a common frame material for artificial fish cribs), and the composite plastic of a commercial fish attractor. Counts of individuals on each substrate were recorded at one-minute intervals for 30 minutes in a common garden style aquarium experiment where all substrate types were equally available. Substrate selection differed among the macroinvertebrate taxa tested. Natural wood was not selected more often than artificial substrates. Trichocorixa rarely selected for the wood substrate over artificial substrates. Ischnura selected the light colored PVC substrate most often and Pachydiplax selected the darker artificial composite most often. Our results suggest that selection of different substrates may be taxon specific and not heavily influenced by material composition.