Predicting maternal body burdens of organochlorine pesticides from eggs and evidence of maternal transfer in Alligator mississippiensis

Abstract

Few data exist regarding maternal-embryonal transfer of organochlorine pesticides (OCPs) in reptiles. The objective of the present study was to evaluate maternal transfer of OCPs in American alligators (Alligator mississippiensis) from low-, intermediate-, and high-OCP-exposure sites. Overall, total OCP burdens ranged from less than 0.8 ppb in blood to more than 44,000 ppb in abdominal adipose tissue (wet wt concentrations). Lipid-adjusted ratios of maternal adipose burdens (total OCPs) to yolk burdens were close to one (0.94 +/- 0.31:1), suggesting that animals were in steady state and that OCPs in eggs originated from adipose lipids. In contrast, lipid-adjusted muscle and liver OCP burdens were greater than yolk OCP burdens, suggesting that lipids in muscle were not utilized during oogenesis and that nonlipid liver tissue sequesters OCPs. Predictive equations were derived for several tissues and several OCP analytes with r2 values ranging from 0.40 to 0.99 (p < 0.05). We suggest that yolk burdens are predictive of maternal tissue burdens for certain tissues and OCPs and that certain OCPs are maternally transferred in the American alligator. Furthermore, we suggest that future studies should investigate the applicability of these predictive equations for assessing maternal exposure in other crocodilian species.

Necropsy Findings in American Alligator Late-Stage Embryos and Hatchlings From Northcentral Florida Lakes Contaminated With Organochlorine Pesticides

“…Prior studies by our laboratory (conducted between 1999 and 2002) have indicated vastly different levels of OCP exposure and early-life-stage mortality across these sites. Lake Lochloosa was selected as the reference site because of its low level of OCPs (overall mean for total OCPs in yolk of 231630 mg/kg) and high clutch viability, defined as the number of live hatchlings/number of eggs in the clutch (71626%) (Rauschenberger et al, 2004). Lake Griffin was selected as an intermediate OCP-exposure site because yolk concentrations average 4,4146617 mg/kg, and Lake Apopka and Emeralda were selected as high OCP-exposure sites because yolk concentrations average 15,91161,786 mg/kg and 15,23861,787 mg/kg, respectively (Rauschenberger et al, 2004).…”

“…Lake Lochloosa was selected as the reference site because of its low level of OCPs (overall mean for total OCPs in yolk of 231630 mg/kg) and high clutch viability, defined as the number of live hatchlings/number of eggs in the clutch (71626%) (Rauschenberger et al, 2004). Lake Griffin was selected as an intermediate OCP-exposure site because yolk concentrations average 4,4146617 mg/kg, and Lake Apopka and Emeralda were selected as high OCP-exposure sites because yolk concentrations average 15,91161,786 mg/kg and 15,23861,787 mg/kg, respectively (Rauschenberger et al, 2004). In addition, clutch success on Lakes Apopka and Griffin and on Emeralda are below those observed at the reference Lochloosa site (51631% , 44633%, and 52635%, respectively) (Rauschenberger et al, 2004).…”

“…Lake Griffin was selected as an intermediate OCP-exposure site because yolk concentrations average 4,4146617 mg/kg, and Lake Apopka and Emeralda were selected as high OCP-exposure sites because yolk concentrations average 15,91161,786 mg/kg and 15,23861,787 mg/kg, respectively (Rauschenberger et al, 2004). In addition, clutch success on Lakes Apopka and Griffin and on Emeralda are below those observed at the reference Lochloosa site (51631% , 44633%, and 52635%, respectively) (Rauschenberger et al, 2004).…”

“…One viable egg was randomly collected from each clutch, opened, and yolk contents stored in glass amber vials at 220 C until analyzed for OCPs as described in Rauschenberger et al (2004). Previous work done in our laboratory has shown that OCP concentrations in alligator yolk does not differ across eggs within a particular clutch (Gross, unpubl.…”

“…Field studies have shown significant exposure of alligators to OCPs, especially in animals inhabiting reflooded muck-farm environments (Rauschenberger et al, 2004;Sepú lveda et al, 2004). The most notable finding so far has been the observation that these populations produce embryos that die before or soon after hatching (Woodward et al, 1993;Masson, 1995;Giroux, 1998;Rauschenberger et al, 2004). Thus, our overall working hypothesis is that one or more OCPs found at these sites are causing decreased earlylife-stage survivorship in animals, and that this decline is the likely cause for the low recruitment observed at these sites.…”