SREL Reprint #2388

Population structure, reproduction, and lipid cycling in the dusky shiner (Notropis cummingsae) in contrasting streams

David L. Schultz

University of Georgia, Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802

Abstract: To document the reproductive and lipid cycle of the dusky shiner, and to determine how environmental differences can influence patterns of reproduction and lipid storage, I sampled dusky shiners from January 1989 to June 1991 from two streams in west central South Carolina: Upper Three Runs and Four Mile Creek. The streams were chosen because of likely differences in primary productivity. Sex, ovary mass, reproductive stage, somatic dry mass, and lipid mass were quantified, as appropriate, for all individuals sampled. There were many differences between the two streams that suggested shiners in Four Mile Creek had greater resource availability during most years, including greater monthly growth, larger ovaries, a longer spawning season, and higher maximum somatic lipid levels. In both streams, females accumulated lipid prior to ovarian enlargement and depleted lipid through a spawning season that spanned three or four months. Males accumulated and depleted lipid in a pattern similar to that seen in females but not to the same extent. There was no apparent lipid accumulation or depletion in immature individuals. There was a clear temporal relationship between lipid accumulation and ovarian enlargement. Lipid accumulation appears to be a prerequisite for reproduction. Lipid accumulation in fall appears to be facultative and not a prerequisite for winter survival. Size-specific differences in reproductive performance appear to be the product of size-specific differences in lipid storage. Large adults became rare in late summer when lipid levels were low. The differences between the two populations are consistent with the theoretical expectation that greater resource availability favors earlier maturation and greater allocation to reproduction.

SREL Reprint #2388

Schultz, D.L. 1999. Population structure, reproduction, and lipid cycling in the dusky shiner (Notropis cummingsae) in contrasting streams. Copeia 3:669-683.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).