Organochlorine compound residues in eggs broad snouted caimans (Caimans latirostris) and bioindicators of reproductive performance

STOKER CORA; ZAYAS MARCELO; GARCÍA, SR; REPETTI, MR; GALOPPO GERMÁN; DURANDO MILENA; BELDOMÉNICO, HR; LUQUE ENRIQUE; MUÑOZ DE TORO MÓNICA

Santa Fe

Workshop; 2nd Latin American Pesticide Residue Workshop; 2009

Organochlorine compounds (OCCs), such as organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), are persistent lipophilic chemicals identified as endocrine disrupter compounds (EDCs) that have broad-ranging effects on wildlife. Recently we reported high frequency and elevated concentrations of OCC residues in human samples from a littoral region in Argentina. OCC levels were positive associated with freshwater fish consumption. Caiman latirostris inhabit wetlands throughout northeastern Argentina and due to their longevity and their position at the top of the food net have the potential to accumulate high concentrations of OCCs. In spite of reproductive performance could be influenced by multiple parameters such as mother age and weather conditions, field and laboratory studies suggested parental OCP exposure may be contributing to low clutch viability in oviparous species. The aims of this study were to estimate the residues of OCCs present in the eggs of C. latirostris and to examine the relationship between OCC levels and parental reproductive parameters. Fourteen caiman clutches were collected from wetlands surrounding Parana River tributaries. The sites have either no history of agriculture or intensive crops. In order to minimize OCCs transfer from nest material, eggs were collected shortly after oviposition. Two to four eggs by clutch were used to establish OCC egg burden by gas–liquid chromatography. Clutch size, hatching success, and hatchling survival were recorded as bioindicators of parental reproductive performance. A high frequency of organochlorine residues and elevated concentrations were found in 89% of egg samples. OCPs most frequently found were: p,p´-DDE in 63%, oxychlordane in 46%, o,p-TDE in 15.2%, HCB, heptachlor, and o,p-DDT in 10.9%, heptachlor epoxide and endosulfan sulfate in 6.5% of the samples. PCBs were present in 50% of the samples. Of the 14 targeted PCBs congeners, BZ 28, 153, 138 and 180 were the most abundant. Concentrations of total PCBs and OCPs were different among nests collected in different sites, while the pattern of OCCs was similar between neighbouring nests. Eggs from nests collected in the area of intensive agriculture had the highest concentrations (∑PCBs═ 40.2±25.1 ng/g lipid and ∑OCPs═ 184±60.2 ng/g lipid). Moreover, endosulfan sulfate was present only in eggs from this site. Fifty percent of the nests with the highest concentrations of OCCs showed an impaired reproductive performance, characterized by low hatching success and a drastic reduction in hatching survival. Our results suggest parental OCC burden may contribute to low reproductive performance while exposure of the developing embryo to these EDCs in the detected concentrations could alter their reproduction in adulthood. Although Caiman latirostris are not currently endangered, OCC exposure could drastically interfere with population stability of this top predator.