Plasma dihydrotestosterone concentrations and phallus size in juvenile American alligators (A. mississippiensis) from contaminated and reference populations

Evidence increasingly suggests that some environmental pollutants are able to permanently affect development of the endocrine system in wildlife. Embr yonic and neonatal exposure to these "endocrine-disrupting contaminants" ca n cause structural and functional abnormalities of the reproductive system. It has recently been hypothesized that demasculinization of a population o f male juvenile American alligators (Alligator mississippiensis) from Lake Apopka, Florida, could result from exposure to antiandrogenic contaminants. The persistent pesticide contaminant p.p'-DDE interacts with the mammalian androgen receptor and antagonizes androgen action in vivo. Wildlife from L ake Apopka, which has been contaminated through agriculture and an industri al accident, exhibit elevated levels of p.p.'-DDE, among other pesticide re sidues. This study provides further evidence of reproductive dysfunction in Lake Apopka juvenile alligators by comparison with a "reference" populatio n from a relatively uncontaminated lake nearby, Lake Woodruff National Wild life Refuge. Phallus size correlated strongly with plasma dihydrotestostero ne (DHT) concentrations or body size in juvenile males from Lake Woodruff I n contrast, males from Lake Apopka had significantly smaller phalli (adjust ed for body size) than those from Lake Woodruff and correlations with body size or plasma DHT concentrations were weak or absent. Plasma DHT concentra tions did not differ significantly between juvenile males from the two lake s. In contrast, plasma DHT concentrations were significantly higher in fema les from Lake Apopka compared to those from Lake Woodruff This is the first report of masculinized female juvenile alligators from Lake Apopka and sug gests that juveniles of both sexes exhibit altered endocrine and reproducti ve parameters.