Organochlorine Pesticides in Chorioallantoic Membranes of Morelet's Crocodile Eggs From Belize

Abstract

Recent studies examined the utility of the chorioallantoic membrane (CAM) as a nonlethal, noninvasive indicator of environmental contaminant exposure in oviparous wildlife. The CAM is a highly vascularized extraembryonic membrane that functions as a site for respiration, nutrient transport, and waste storage during embryonic development. After hatching, the CAM is usually discarded with the eggshell and can be used for chemical residue analysis. Chorioallantoic membranes have been used successfully to examine contaminant exposure and predict chemical concentrations in multiple species of birds and reptiles. In this study, we examined organochlorine (OC) pesticide concentrations in CAMs from eggs of Morelet's crocodiles (Crocodylus moreletii) from northern Belize. Multiple OCs were detected in crocodile CAMs, including aldrin, dieldrin, endrin, dichlorodiphenyltrichloroethane, dichlorodiphenyldichloroethane, dichlorodiphenyldichloroethylene (DDE), heptachlor, lindane, and methoxychlor. Number and concentrations of OC compounds in CAMs were variable. The most prevalent contaminant detected was DDE, which occurred in 69% of CAMs, with concentrations ranging from 0.3 parts per billion (ppb) to 17.0 ppb. The OC burdens in crocodile CAMs confirm contamination of eggs and suggest exposure in embryos and maternal females. These results further support the use of CAMs as qualitative indicators of OC exposure in oviparous wildlife. The efficacy of this sampling technique in the field will depend on the logistics and cost associated with CAM collection and the specific life history traits of the wildlife species.

Very high concentrations of DDE and toxaphene residues in crocodiles from the Ord River, Western Australia: an investigation into possible endocrine disruption

“…The endocrine disrupting properties of toxaphene and of p,p 0 -DDE (2,2-bis-(p-chlorophenyl)-1,1-dichloroethene), the main persistent metabolite of DDT, have been well established [1][2][3][4][5][6][7] but previously reported work on crocodilian species have, apart from a few simple studies 8,9 been limited to the analysis of residue levels in eggs [10][11][12][13][14][15] and to studies of juvenile American alligators Alligator mississippiensis 3,4,16,17 The ecotoxicology of crocodilians has been comprehensively reviewed by Campbell. 18 The isolation of the OIA, the simplicity of its drainage system, and the exact record of pesticide application 19 make the region a valuable natural laboratory to study the long-term rate of degradation of DDT and toxaphene, and the possible endocrine disrupting effects of pesticide residues on wildlife.…”

Endocrine Disruption of Reproduction in Reptiles

“…Further, studies of Lake Apopka alligators have examined contaminant levels in muscle, blood, and liver, and have noted elevated levels of many organochlorine contaminants as well as PCBs in these tissues as compared to alligators from a relatively pristine and ecologically similar site in FloridadLake Woodruff National Wildlife Refugedwhich has been used as a reference site for more than 20 years (Delany, Bell, & Sundlof, 1988;Guillette, Brock, Rooney, & Woodward, 1999a;Garrison, Guillette, Wiese, & Avants, 2009) (Figure 14.4; Table 14.1). Organochlorine (OC) contaminants have been detected in several crocodilian species including the American alligator, the American crocodile (Crocodylus acutus), Morelet's crocodile (Crocodylus moreletii), the Australian freshwater crocodile (Crocodylus johnstoni), and the Nile crocodile (Crocodylus niloticus) (Campbell, 2003;Pepper et al, 2004;Rauschenberger et al, 2004a;Sepulveda et al, 2004;Yoshikane et al, 2006).…”

Accumulation of organochlorine pesticides in fat tissue of wild Nile crocodiles (Crocodylus niloticus) from iSimangaliso Wetland Park, South Africa

“…Owing to their high trophic status and long life span, crocodiles are particularly susceptible to the accumulation of contaminants released into the environment and OCP residues have been detected in crocodilians from multiple localities (e.g., Phelps et al, 1989;Campbell, 2002;Rauschenberger et al, 2004;Yoshikane et al, 2006;Wu et al, 2014). Contaminant studies have focused largely on residues in eggs and include American alligators (Alligator mississippiensis) (Heinz et al, 1991;Cobb et al, 1997;Sepúlveda et al, 2004), American crocodiles (Crocodylus acutus) (Hall et al, 1979;Wu et al, 2000), Morelet's crocodiles (Crocodylus moreletii) (Wu et al, 2000;Pepper et al, 2004;Wu et al, 2006), Nile crocodiles (Crocodylus niloticus) (Wessels et al, 1980;Phelps et al, 1986;Skaare et al, 1991;Bouwman et al, 2014) and broad-snouted caimans (Caiman latirostris) (Stoker et al, 2011). OCPs have also been detected in the caudal scutes of Morelet's crocodiles (Sherwin et al, 2016) and American crocodiles from Central America (Rainwater et al, 2007;Rainwater et al, 2011).…”