By Sarah Harrison | AFS Contributing Editor. E-mail: [email protected]
In this study, Joseph H. Tarnecki and William F. Patterson of the Dauphin Island Sea Lab, University of South Alabama, examined the impact of the BP Deepwater Horizon (DWH) oil spill on the diet and trophic position of Red Snapper Lutjanus campechanus off the coasts of Alabama and Florida. This study is unique because the authors had 18 months of pre-spill data. A common problem that has plagued evaluations of oil spill impacts is the general lacking of baseline data needed for comparisons.
In their investigations, the authors found that Red Snapper diet and trophic position differed significantly before and after DWH. Following the spill, they observed a decline in the consumption of pelagic zooplankton, both at natural and artificial reefs, and hypothesized that zooplankton had been negatively affected by the oil and dispersants. As a result, Red Snapper, which tend to be generalist mesopredators (think broad diets), had to switch their diet to higher trophic level prey: decapods, cephalopods, stomatopods, and fish. Stable isotope analysis confirmed the increase in trophic level feedings observed from stomach analysis in addition to the switch to more benthic prey (due to loss of pelagic zooplankton). However, unlike stomach analysis, which only provides a snapshot of ingested food in the days prior to death, stable isotopes take months to be incorporated into the muscle tissue of fish, suggesting these shifts in diet were persistent for several months.
Look for more exciting DWH oil spill results from Patterson’s lab. He has two more articles ready for submission that follow on this paper. The first demonstrates persistent trophic shifts of Red Snapper and Tomtate Haemulon aurolineatum after the spill stable isotope analysis and describes shifts in size at age. The second article depicts reef fish oil exposure inferred from liver PAH concentrations and changes in reef communities from 2009 to 2014.
Tarnecki, J. H., and W. F. Patterson. 2015. Changes in Red Snapper diet and trophic ecology following the Deepwater Horizon oil spill. Marine and Coastal Fisheries: Dynamics, Management, and Ecosystem Science 7:135–147. dx.doi.org/10.1080/19425120.2015.1020402