Ecology of the redfin darter and a potential emerging threat to its habitat

Abstract

The basic biologies and ecologies of most freshwater fishes throughout the world are poorly understood. But such knowledge may be critical for conservation decisions. The redfin darter (Etheostoma whipplei), a poorly understood fish species, is an excellent model for highlighting this situation. Much of the limited range of this species is experiencing nontraditional natural gas extraction activities including hydraulic fracturing, which may be a significant source of silt input for streams. We investigated aspects of the ecology and metrics of reproductive success of redfin darters in central Arkansas. We examined habitat occupation through quantitative surveys of fish assemblages and habitat variables, and reproductive life history through field and laboratory surveys in Cypress Creek, Arkansas. We also examined the proportion of young fishes in populations relative to intensity of natural gas extraction activity. Ordination analysis found habitat gradients relating primarily to stream size. Redfin darters had the highest relative abundance in samples in small, high gradient streams. Redfin darters reproduce in the spring, peaking with the rainy season, using larger substrate than their close relatives. Reproductive success appears to be negatively related to natural gas extraction intensity. Redfin darters reproduce at both a time and in a habitat which may be especially susceptible to siltation from natural gas extraction activities, which may be reflected in fewer young fishes in populations. Our research highlights the importance of life history data in understanding responses to novel disturbances in freshwater fishes.