PARENT SESSION
Oral Session #36: Conservation of aquatic systems: Ecology and ecotoxicology. Presiding: R. Lathrop.
Tuesday, August 7, 2001. 1:00 PM to 5:15 PM. Hall of Ideas H.

The impact of PCB 153 on male advertisement calling in Rana pipiens.

LeVering, Kate¹, Nemec, Jennifer¹, Karasov, William¹, ¹

ABSTRACT- Polychlorinated biphenyls (PCBs) are well known endocrine disrupters, and multiple studies, in both humans and wildlife, have shown PCB 153 to be one of the two most common congeners in tissue. Work on mammalian models suggests that PCB 153 is estrogenic in nature. In male rats, it causes increased levels of estradiol and T4. Relatively little is known about how these physiological changes ultimately affect behavior. Xenobiotic estrogenic compounds are capable of decreasing male sexual displays in fish, though the effects of PCB 153 on the reproductive endocrine and behavioral axes in unknown. Here we use male Rana pipiens to test the hypothesis that PCB 153 can decrease male sexual behavior in a manner similar to estradiol. Males in this species congregate in large choruses and court females by producing advertisement calls. Stimulation to call is partially provided by nearby conspecifics concurrently advertising for mates. Furthermore, the closer and louder conspecific song appears to be, the more likely the focal frog is to call. Our study took advantage of this by using a series of playbacks of conspecific chorus at different amplitudes to assess the motivation of male frogs to call, following administration of one of three treatments. The treatment groups were injection of: 1) corn oil vehicle, 2) 17-estradiol + vehicle, or 3) PCB 153 + vehicle. We then measured motivation by recording the calling response of each male. Measurements were taken both before and after administration of the treatments. Surprisingly, we found that the PCB 153 group called at a significantly higher rate than both the control and the estradiol groups (p = 0.05 and p = 0.02 respectively). We conclude that PCB 153 does not have estrogenic effects on mating behavior in male Rana pipiens.

KEY WORDS: Rana pipiens, behavior, reproduction, PCB 153