Stream inflow and predation risk affect littoral habitat selection by benthic fish

Abstract

We examined small, fishless headwater streams to determine whether transport of macroinvertebrates into the littoral zone of an oligotrophic lake augmented food availability for Cottus asper, an abundant predatory fish in our study system. We sampled fish and macroinvertebrates during the recruitment and growth season of 2 years, either monthly (2004) or bi-monthly (2005), to observe whether stream inputs increased prey availability and whether variation in total macroinvertebrate biomass was tracked by fish. Our results suggest that the effect of fishless headwater streams on downstream fish may not always be through direct delivery of food. In this study system, fish preferred stream inflow plots, but this preference interacted with macroinvertebrate biomass in a manner that was difficult to explain. For young-of-the-year, predation risk was related to the preference for stream inflows, although the specific factor that mitigates predation risk remains poorly understood.

Citation

Polivka, Karl M.; Friedli, Lisa M.; Green, Elizabeth C. 2013. Stream inflow and predation risk affect littoral habitat selection by benthic fish. Freshwater Biology. 58(5): 986-994.