Despite their highly mobile nature, large epipelagic rays were likely exposed to crude oil and chemical dispersant CorexitTMfrom the Deepwater Horizon (DWH) incident in the northern Gulf of Mexico. Aerial surveyors of the immediately impacted area (i.e. SE Louisiana) reported rays swimming through oiled surface waters shortly after the blowout in spring 2010. This particular time-frame (i.e. season) has been shown to support higher than average densities of rays in this region.
However, the temporal and spatial extent of the exposure remains unknown due to limited distribution and habitat use data on these species. With their k-selected life history and historical use of the impacted area, epipelagic ray populations may have endured significant losses from the DWH incident. Alternatively, habitat use of these animals may have been influenced by the sudden changes in environmental conditions causing them to shift their distribution and thus sustained natural population levels of these rays.
Utilizing a historical aerial data set (2008 – present) we are examining the potential impact of DWH on the distribution and densities of two surface utilizing ray species, the cownose (Rhinoptera bonasus) and manta (Manta birostris), in the northern Gulf of Mexico. Additionally, to better estimate fine-scale habitat use, including affinities to petroleum platforms and other offshore structures, we are tracking the movements of these two species with satellite telemetry.