PARENT SESSION
Tuesday, August 8, 5:00-6:30 pm
Poster Session 8 - Aquatic ecology
Exhibit Hall, Ballroom Level, Cook Convention Center

Density-dependent effects on growth and reproduction of the orangethroat darter, Etheostoma spectabile (Pisces: Percidae).

Fortner, Allison^*,1, ¹ University of Oklahoma, Norman, OK

ABSTRACT- Density dependence is an important factor structuring biological systems and can affect various aspects of an organism's life history. The orangethroat darter, Etheostoma spectabile (Percidae), occurs across the midwestern U.S., from tributaries of the Great Lakes, west to Nebraska, and south to gulf drainages in Texas, and usually inhabits shallow gravel riffles, runs, or pools of clear headwaters or creeks. I conducted an experiment to determine the effects of population density on growth rate and reproduction. Young-of-year orangethroat darters were housed in outdoor 190-liter riffle-like mesocosms for eight months at four densities. Length of fishes and evidence of reproductive maturity were recorded every two months. Darters in low-density treatments showed accelerated growth compared to those in high-density treatments, and a higher percentage of fish in low-density treatments reached sexual maturity. In addition, darters in low-density treatments were reproductive earlier in the season than in the high-density treatments and size at reproduction varied with density. Since body size influences many aspects of reproduction in fishes, these results suggest that reproduction in E. spectabile is density-dependent.

Key words: Etheostoma spectabile, density dependence, streams