Assessment of early life stage mahi-mahi windows of sensitivity during acute exposures to Deepwater Horizon crude oil

The primary windows of sensitivity during 96-hr exposures of early life stage mahi-mahi to Deepwater Horizon crude oil prepared as a high-energy water accommodated fraction (HEWAF), a thin surface slick, and a low-energy water accomodated fraction (LEWAF) were characterized. THe LWEAF method produces total polycyclic aromatic hydrocarbon (PAH)concentrations and compositions in the water column similar to that using the slick method without producing a surface slick, thereby aiding in distinguishing effects attributable to the surface slick itself and those attributable to the dissolved PAH in the underlying water. Median lethal effect concentrations were determined from the HEWAF and LEWAF exposures using a series of 96-hr bioassays with varying windows of oil exposure ranging from 2-hr to 96-hr. Results revealaed that exposures to environmentally relevant PAH concentrations of much shorter duration than 96-hr can impact significnatly toxicity to mahi-mahi. Although the period surrounding hatch was identified as likely the most sensitive to crude oil exposure for mahi-mahi, toxicity was also elicited by exposures during other developmental periods.