Overall Research Project Description Elasmobranchii’ s diverse reproductive strategies pose an unknown amount of risk to pregnant females from the level of embryonic maternal investment. This study aims to investigate the frequency and nutritional content of intrauterine histotroph secretions of Matrotrophic stingrays in Eastern Gulf of Mexico and assess the effects of embryonic maternal investment on the physical performance of gravid females throughout gestation.
Mature female Hypanus sabinus and Rhinoptera bonasus will be collected throughout all stages of gestation with seines, gillnets, and otter-trawls independently and in collaboration with Fish and Wildlife Research Institute’s Fishery-Independent Monitoring Program. These specimens are euthanized and dissected to remove developing embryos and ova for organic dry weight procedures and to quantify embryonic maternal investment at all stages of gestation. Histotroph will be assayed for total energic content, carbohydrates, fatty acids, proteins, and lipids.
Lastly, 10 H. sabinus will be collected at early gestation and transported to Florida State University Coastal and Marine Laboratory facilities for respirometry trials. The individual’s average oxygen consumption rate will be measured over a six-hour trial period and repeated every three weeks for six months to identify changes in physical performance at as gestation progresses.
Identifying intraspecific and interspecific variation in fluids that provide embryonic nourishment is integral to understanding how these reproductive strategies contribute to elasmobranch fitness. Negative physiological effects during gestation would directly impact a female and her litters ‘ability to survive in the wild during their most vulnerable life stage.