Meeting Abstract
P2.32 Friday, Jan. 4 Comparative Bioenergetics of Endangered Freshwater Fishes and Widespread Relatives SANDEL, Michael*; OTT, Brian; The University of Alabama; USDA-ARS Catfish Genetics Research Unit kwksand@yahoo.com
Most geographically restricted species are endangered by human disturbance. It is necessary to understand the natural factors that restrict such species’ distributions in order to best conserve them. Interestingly, highly endemic species are often closely related to more widespread taxa. It is unknown whether this “dispersion disproportion” is due to local constraints or the evolutionary history of species. This study aims to determine the relationship between ambient thermal variation and metabolic rate among four freshwater fish species, and to determine if this relationship differs among those widespread and those geographically restricted. Two species pairs are examined, each of which contains a widespread and a narrowly distributed species. The spring pygmy sunfish and the tuscumbia darter are restricted to thermally stable spring-fed streams in the Highland Rim of northern Alabama. The banded pygmy sunfish and the gulf darter are widespread and common within the Coastal Plain, and are not restricted to spring systems. Ecological similarity between sister species suggests that abiotic factors may play an important role in accounting for the “dispersion disproportion” between these fishes. Closed chamber respirometry is used to determine metabolic rate per species, measured as mass-specific oxygen consumption. Temperature variation, activity, and feeding are also considered. Results suggest a mechanistic explanation for the “dispersion disproportion”, and implicate the relative importance of local constraints and the evolutionary history of species. The parameters calculated during this study are primary to the formation of bioenergetic models for each species. When complete, these models will allow prediction of species’ response to environmental change, and will aid in the conservation of all geographically restricted freshwater fishes.
