MP10 PCB Toxicity in Aquatic Organisms- Endocrine Effects
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(SPA-1117-855176) Creek chub (Semotilus atromaculatus Mitchill) reproduction in PCB-contaminated streams in Indiana.

Sparks, D¹, Simon, T¹, Tosick, M¹, Millsap, D^{1, 2}, Henshel, D², ¹ U.S. Fish and Wildlife Service, Bloomington, IN, USA² Indiana University, Bloomington, IN, USA

ABSTRACT- We examined creek chubs from two PCB contaminated streams (Clear Creek and Richland Creek) at three locations and a reference stream (Little Indian Creek) to determine if reproductive measures were correlated with in-situ PCB exposure. Throughout this study, no spawning activity was observed at either location in Clear Creek, although some very small young-of-the-year creek chub fry were observed at the downstream location (CC2) by late summer. Creek chub nests were observed in both Richland Creek and Little Indian Creek but young of the year were common only in Little Indian Creek. Differences in synchronization of male and female sexual maturation were observed at the PCB sites. By mid-May at the reference site spawning was complete. We observed no reference females with maturing or ripe ova, whereas at our PCB contaminated locations several females were found carrying deteriorating ova in various stages of maturity as late as July. At CC2, we observed females with deteriorating ovaries in 1 and 2-year olds, and older age classes of females were absent. Both egg quality (e.g. shape, coloration) and egg sizes were reduced at the PCB-contaminated sites. Males at the PCB-contaminated sites tended to exhibit female secondary sex characteristics, with reductions in seasonal testes maturation and nuptial tubercle development. We observed significant differences in ovary weight and fecundity between PCB sites and the reference site. The percent volume of developing ova were significantly different between PCB sites and the reference site for early maturing, mature, and ripe ova, but not latent ova. A small follow-up study was conducted at 4 PCB-contaminated streams and a reference site wherein females were collected just prior to spawning and ovary conditions were qualitatively assessed (GSI, maturation, coloration) and regressed against congener specific PCB analysis of the ovaries and whole body concentrations.

Key words: PCBs, ovarian atresia, gonadal maturation, secondary sex characteristics