Quantification of Maternal Offloading of Organic Contaminants in Elasmobranchs Using the Histotrophic Round Stingray (Urobatis halleri) as a Model

摘要

Maternal offloading is one route by which young animals may accumulate persistent organic pollutants, such as dichlorodiphenyltrichloroethane (DDT) and polychlorinated biphenyls (PCBs), but has not been well documented in e1asmobranchs despite their propensity to accumulate high concentrations of contaminants Using the round stingray (Urobatis halleri) as a coastal elasmobranch model,we examined maternal offloading processes at two stages in the stingray's entire reproductive cycle. Post-ovulated and near-term pregnant female stingrays were sampled from southern California, and organic contaminants were measured in the ova and embrvonic tissues and compared to concentrations measured in corresponding female livers to determine route and extent of transfer. Total organic contaminant loads measured in ovulated eggs were about two times lower than loads measured in embryos (p＜ 0001) indicating mothers have the ability to transfer contaminants throughout pregnancy Contaminant loads measured in pups showed a positive relationship with mother's contaminant concentrations (p ＜ 0.001); However, mothers offloaded relatively low percentages (1.5 ± 1.7%) of their total contaminant load using contaminants measured in the liver as a proxy. However, histotrophy is only one form of supplemental provisioning utilized by elasmobranchs and variation in reproductive modes likely influences the extent to which female elasmobranchs may maternally offload contaminants.