Development of the Fish Community in a New South Carolina Reservoir

Abstract

-Twenty-eight species of fish inhabited Steel Creek before it was impounded in 1985 to create L Lake. By early 1986, six of these species had successfully colonized L Lake (i.e., established reproducing populations); all were trophic and habitat generalists. With one exception, these species declined or disappeared during the next 2 yr as species more typical of reservoir ecosystems were introduced into L Lake. The introduced species were larger-bodied and exhibited greater trophic specialization than the original colonists. The close correspondence between the decline of the early colonists and the increase of the reservoir species, coupled with an absence of concurrent changes in the abiotic environment likely to result in species losses, indicated that interspecific interactions were responsible for the observed community changes. Both competition and predation appeared to be contributing factors, although the relative importance of these processes could not be determined. Given the rate and order in which species colonized L Lake, there was no evidence of priority effects, in which previously established species prevent colonization by later arriving species. The development of the L Lake fish community during the 1st 3 yr appeared to be a largely deterministic process, controlled initially by the habitat requirements and preferences of the species that had access to L Lake from Steel Creek and later by interspecific interactions between the original colonists of L lake and the introduced species.