Variation in sex steroids and phallus size in juvenile American alligators ( Alligator mississippiensis) collected from 3 sites within the Kissimmee-Everglades drainage in Florida (USA)

• Published in: Chemosphere (Oxford) 2004-07, Vol.56 (4), p.335-345
• Main Authors: Gunderson, Mark P., Bermudez, Dieldrich S., Bryan, Teresa A., Degala, Satish, Edwards, Thea M., Kools, Stefan A.E., Milnes, Matthew R., Woodward, Allan R., Guillette, Louis J.
• Format: Article
• Language: English
• Subjects: Alligator mississippiensis; Alligators and Crocodiles - anatomy & histology; Alligators and Crocodiles - metabolism; Analysis of Variance; Animal, plant and microbial ecology; Animals; Applied ecology; Biological and medical sciences; Biomarkers; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on vertebrates; Endocrine disruption; Endpoint Determination; Environmental Pollutants - analysis; Environmental Pollutants - toxicity; Estradiol - blood; Estradiol - metabolism; Everglades; Female; Florida; Freshwater; Fundamental and applied biological sciences. Psychology; Geologic Sediments - analysis; Hydrocarbons, Chlorinated; Insecticides - analysis; Insecticides - toxicity; Lake Okeechobee; Male; Penis - anatomy & histology; Penis - drug effects; Pesticides; Radioimmunoassay; Reptilia. Amphibia; Testosterone - blood; Testosterone - metabolism; Variance; Wildlife
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2004.01.020

This 3-year study was designed to examine variation in plasma sex steroids, phallus size, and the standard error (S.E.) associated with these endpoints in juvenile alligators collected from 3 sites within the Kissimmee-Everglades drainage (Florida, USA) with varying concentrations of sediment organochlorine contaminants. We hypothesized that decreased plasma sex steroid concentrations and phallus size would be observed in the higher contaminant site when compared to the intermediate and lower contaminant sites. Furthermore, we hypothesized that greater S.E. associated with these endpoints would be observed for the populations from more contaminated sites. We found that differences existed with females from the higher contaminant site exhibiting lower plasma estradiol-17β (E 2) and testosterone (T) concentrations. Males from the higher contaminant site exhibited smaller phallus sizes than males from the intermediate and lower contaminant sites. Smaller phallus size in this case differed from that reported in Lake Apopka male alligators [Gen. Comp. Endocrinol. 116 (1999) 356] in that a significant positive relationship between body size and phallus size existed. No difference among sites was observed in plasma T for males. Lower S.E. was associated with E 2 and T concentrations in females from the higher contaminant site and in phallus size in males from the higher contaminant site. This pattern was opposite to what we had hypothesized. We concluded that variation in plasma E 2 and T concentrations, phallus size, and the S.E. associated with these endpoints exists among the 3 sites with the patterns matching the patterns of organochlorine contamination, although S.E. patterns were opposite to what was predicted.