The Effects of the Deepwater Horizon Oil Spill on Blue Crab Embryos

Blue crabs (Callinectes Sapidus) are ubiquitous along the east coast; however, they play a particularly integral role in the Gulf of Mexico (GOM), where, not only are they a keystone species, but they are also socioeconomically important. The survival of embryos is necessary to insure adequate recruitment into the next generation. Because the Deepwater Horizon oil spill occurred during the peak of the blue crab spawning season, the incident likely impacted blue crab embryos. This study was conducted in order to assess the effect of oil on embryonic growth and development. The eggs from seven different female crabs were collected from the GOM throughout the spawning season and exposed to an oil concentration of 500ppm (the approximate concentration of oil at the site of the DWH). We found that, while the overall mortality rate and the proportion hatched was not significantly different between embryos that were exposed to oil and those not exposed to oil, the proportion of prezoea in the experimental group was significantly greater. Prezoea are known to occur in suboptimal conditions such as low salinities, or bacterial and fungal infection, and have been documented to have reduced survival. Our results support these findings and indicate that oil concentrations of 500 ppm negatively impact the development of blue crab embryos. This study sheds light on a critical, but poorly investigated, phase of an important species’ life cycle in addition to providing further insight into the effects of the DWH spill.