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Final Progress Reports: University of Florida: Endocrine-Disrupting Effects of Chlorinated Hydrocarbons on Wildlife

Superfund Research Program

Endocrine-Disrupting Effects of Chlorinated Hydrocarbons on Wildlife

Project Leader: Timothy S. Gross
Grant Number: P42ES007375
Funding Period: 1995 - 2000

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Final Progress Reports

Year:   1999 

This project evaluated endocrine-disrupting effects of chlorinated hydrocarbon contamination on wildlife within central Florida lakes. Researchers examined fish and alligators for endocrine-disruption, alterations of sexual development and biomarkers for contaminant exposure. Project investigators focused on: 1) the reproductive endpoint significance of the endocrine disrupting effects observed for largemouth bass on Emeralda Marsh, 2) the incidence of altered secondary sex characteristics for alligators from Lake Apopka, 3) a survey of egg and maternal contaminants in alligators and any potential correlations to subsequent egg quality, hatchability and developmental mortality, 4) a determination of fertilization failure versus early neonatal mortality for non-banded alligator eggs from Lake Apopka, and 5) additional evaluations of vitellogenin responses in fish following acute exposures to pesticides. Largemouth bass from Emeralda marsh have been documented to exhibit decreased sex steroids and vitellogenin. During year 5, largemouth adults were removed from the Emeralda Marsh and spawned under control conditions in ponds. Bass from all sites spawned successfully, however, bass from the two most impacted sites, Long and Knight Farm, produced fewer eggs, decreased egg hatchability, and increased neonatal mortalities. These data indicate that decreased biomarkers do not necessarily translate to complete reproductive dysfunctions, but rather a large decrease in egg quality and embryo/neonate quality. A four-year growth study of alligator neonates was completed to document the potential for altered penis size due to site effects and pesticide exposure as neonates. Alligator neonates from Lakes Apopka and Woodruff were raised under control conditions and sacrificed at 4 years of age. Results did not detect any difference in penis size between sites, which suggests that previous field efforts may be inaccurate due to inabilities to age animals. A significant effort to collect adult female alligators and their respective eggs/clutches was also undertaken during year 5. This project was designed to examine a variety of chlorinated pesticides in maternal and egg tissues relative to egg/embryo quality and to enable the collection of un-banded eggs. Results indicated that chlorinated pesticides in eggs did not correlate to subsequent egg/embryo quality, but that concentrations of several pesticides in adult females did correlate well. These data continue to support the recent hypothesis of effects mediated through the maternal system rather than via egg/embryo exposure. Historically, decreased egg hatchability (as observed for Lakes Apopka and Griffin) is associated with significant numbers of eggs within clutches that are not banded. This lack of banding can be interpreted as infertility or very early embryonic mortality. A preliminary analysis of parentage suggested that unbanded eggs are indeed fertilized and that early embryonic death is most probably occurring. Overall, these data demonstrate endocrine disrupting effects of chlorinated hydrocarbons. The researchers have refocused attention from egg/embryo direct effects to maternal effects and therefore indirect embryo/egg effects. These future efforts will focus on developmental mortality in alligators and bass and to the maternal exposure mechanisms involved.

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