Plasma steroid concentrations and male phallus size in juvenile alligatorsfrom seven Florida lakes

Neonatal and juvenile alligators from contaminated Lake Apopka in central F lorida exhibit abnormal plasma sex steroid concentrations as well as morpho logical abnormalities of the gonad and phallus. This study addresses whethe r similar abnormalities occur in juvenile alligators inhabiting six other l akes in Florida. For analysis, animals were partitioned into two subsets, a nimals 40-79 cm total length (1-3 years old) and juveniles 80-130 cm total length (3-7 years old). Plasma testosterone (T) concentrations were lower i n small males from lakes Apopka, Griffin, and Jessup than from Lake Woodruf f National Wildlife Refuge (NWR). Similar differences were observed in the larger juveniles, with males from lakes Jessup, Apopka, and Okeechobee havi ng lower plasma T concentrations than Lake Woodruff males. Plasma estradiol -17 beta (E-2) concentrations were significantly elevated in larger juvenil e males from Lake Apopka compared to Lake Woodruff NWR. When compared to sm all juvenile females from Lake Woodruff NWR, females from lakes Griffin, Ap opka, Orange, and Okeechobee had elevated plasma E-2 concentrations. Phallu s size was significantly smaller in males from lakes Griffin and Apopka vc; hen compared to males from Lake Woodruff NWR. An association existed betwee n body size and phallus size on all lakes except Lake Apopka and between ph allus size and plasma T concentration on all lakes except lakes Apopka and Orange. Multiple regression analysis, with body size and plasma T concentra tion as independent covariables, explained the majority of the variation in phallus size on all lakes. These data suggest that the differences in sex steroids and phallus size observed in alligators from Lake Apopka are not l imited to that lake, nor to one with a history of a major pesticide spill. Further work examining the relationship of sex steroids and phallus size wi th specific biotic and abiotic factors, such as antiandrogenic or estrogeni c contaminants, is needed, (C) 1999 Academic Press.