Summary:
In order to assess impacts of the 2010 Deepwater Horizon oil spill on coastal fisheries we will look at both short-term and medium-term effects on individual fish in two species. We will then use the information obtained to model the population-wide effects. To assess short-term effects of the oil spill, two estuarine fish species: Cynoscion nebulosus (spotted seatrout) and Sciaenops ocellatus (red drum) were collected in 2010 at four locations along the Mississippi and Louisiana coast that received oil inflow.
These two fish species have varied life histories and therefore may have dissimilar responses to the introduction of oil into their habitat. Various biomarker stress responses will be evaluated within these fish; such as Cytochrome P450-1A (CYP1A) levels, aromatase and EROD activity. These biomarkers stress responses are indicative of animals breaking down hydrocarbons via the Phase I biotransformation pathway. The genes of interest (CYP1A and CYP19) will be sequenced for both species. In 2011, a series of toxicological assays will be conducted on juveniles from both species to measure molecular stress response and these data will be compared to field observations made in 2010.
Fish growth, health, and reproductive condition will be used as indicators to asses medium-term effects of the oil spill on C. nebulosus. Otholiths will be collected at one year following the oil spill and average fish growth in 2010 will be determined using otolith increment analysis. The incremental spacing and ring pattern in post-oil spill otoliths will be compared to historical otolith records from the same location and age to determine if significant growth reductions in fish growth occurred. Various morphometric indices will also be used to evaluate fish health, including Condition Factor (CF), Gonadosomatic Index (GSI), and Hepatosomatic Index (HSI). Histological analysis will be used to assess reproductive condition in one year old spotted seatrout and will also be compared to historical data.
The results obtained for the molecular bioindicators will be compared to the growth, health, and reproductive condition data to test for habitat-specific correlations between short-term stress and medium-term effects associated with the oil spill. These data will then be used to structure a population growth model in order to project possible population-level impacts of the findings.