Serum Concentrations of Various Environmental Contaminants and Their Relationship to Sex Steroid Concentrations and Phallus Size in Juvenile American Alligators

Abstract

Recent studies have reported a number of abnormalities in the hatchling and juvenile alligators of Lake Apopka, FL (USA). These abnormalities include modifications of plasma concentrations of sex steroids in males and females as well as abnormalities in gonadal morphology, gonadal enzyme activity, and steroidogenesis. Embryonic exposure to environmental contaminants in the eggs has been hypothesized to be the causal agent for these changes. However, posthatchling exposure can also contribute to changes in reproductive and endocrine functioning. We have detected serum concentrations of 16 of 18 organochlorine pesticides or metabolites (OCs) and 23 of 28 congener-specific polychlorinated biphenyls (PCBs) examined in juvenile alligators from Lake Apopka, Orange Lake, and Lake Woodruff National Wildlife Refuge. Lake Apopka juveniles had significantly elevated serum concentrations of p,p'-DDE, dieldrin, endrin, mirex, oxychlordane, SigmaDDTs, and SigmaPCBs compared to juveniles from the other lakes. Further, we observed no correlations between serum contaminant concentrations and sex steroid concentrations (estradiol-17beta and testosterone). However, serum testosterone was significantly lower in males from Lake Apopka and Orange Lake compared to Lake Woodruff NWR. We did not observe relationships between phallus size or other body parameters and serum contaminant levels. Phallus size was smaller in males from Lake Apopka even after adjustment for body size. We suggest that the observations previously reported for juvenile alligators-and observed again in this study-are apparently not associated with the current serum levels of the environmental contaminants we measured, but could be due to exposures during embryonic development to these or other pollutants. Future studies must determine if a causal relationship exists between the contaminants found in alligator eggs and abnormalities observed in the hatchlings and persisting in juveniles.

Pathology, Physiologic Parameters, Tissue Contaminants, and Tissue Thiamine in Morbid and Healthy Central Florida Adult American Alligators (Alligator Mississippiensis)

“…Whether elevated total protein in impaired alligators was due to dehydration or resulted from systemic inflammatory from a pathogen remains unknown, however, no microbial pathogens were found. Healthy alligator plasma total protein values were similar to published data (Lance et al 1983(Lance et al , 2001Guillette et al 1997). The cause for increased plasma globulin concentration in impaired Lake Griffin alligators is not known but acute tissue injury or long-term production of antibodies (immunoglobulins) have been associated.…”

“…Detectable concentrations of OCs were below concentrations normally associated with mortality in other wildlife (Eisler and Jacknow, 1985;Blus, 1996;Marburger, et al 2002). In all cases where OC pesticides were detected, the highest OC concentrations measured were below or comparable to concentrations recorded for alligators in other Florida lakes with no major mortality events (Guillette et al, 1999;Sepú lveda et al, 2004). There was no indication of exposure to OCs or their breakdown products, being responsible for observed neural impairment or mortality of alligators.…”

Heavy Metal and Selenium Concentrations in Liver Tissue From Wild American Alligator (Alligator Mississippiensis) Livers Near Charleston, South Carolina

“…The release of heavy metals into aquatic systems has been increasing with increased industrial use of heavy metals, such as mercury (Hg) and lead (Pb), which can bioaccumulate in organisms, especially higher trophic level animals. The American alligator (Alligator mississippiensis) is a long-lived, top predator found throughout coastal areas in the southeastern US and is susceptible to various environmental contaminants, including those of heavy metals and organohalogen compounds (Delany et al, 1988;Brisbin et al, 1998;Guillette et al, 1999;Burger et al, 2000;Khan and Tansel, 2000). Alligator populations have recovered in most of their range following their listing on the endangered species list in the early 1970s.…”

“…However, local populations of alligators can decline as a result of anthropogenic stressors such as chemical and agricultural runoff (Jennings et al, 1988). Heavy metals and other contaminants have been suggested as the cause of reproductive and developmental abnormalities in American alligators (Guillette et al, 1999). Most studies have focused on mercury and organohalogen contamination in American alligators located in Florida (Heaton-Jones et al, 1997;Guillette et al, 1999;Khan and Tansel, 2000;Rumbold et al, 2002).…”

“…Heavy metals and other contaminants have been suggested as the cause of reproductive and developmental abnormalities in American alligators (Guillette et al, 1999). Most studies have focused on mercury and organohalogen contamination in American alligators located in Florida (Heaton-Jones et al, 1997;Guillette et al, 1999;Khan and Tansel, 2000;Rumbold et al, 2002). Heavy metals other than Hg in tissues from wild American alligator populations have been the focus of only a few studies (Lance and Elsey, 1983;Delany et al, 1988;Burger et al, 2000), although alligators have been shown to be a good, suitable monitor of localized pollution (Delany et al, 1988).…”