Preliminary Analysis of the Effects of the Macondo Oil Spill on Coastal Diving Ducks in the Northern Gulf of Mexico

Aims: The explosion and sinking of the Macondo drilling platform resulted in one of the largest marine oil spills in history but with largely uncertain ecological consequences. Among the lesser studied but potentially greater concerns are population and toxicological effects of the spill on migratory birds, including many economically-important waterfowl that overwinter in the area. Here, we present a preliminary analysis of oil effects to coastal diving ducks.

Study Design: Oiled areas of coastal Alabama and reference areas on the Florida Gulf of Mexico coast were used to assess oil impacts in waterfowl.

Place and Duration of Study: Waterfowl were collected in oiled and unoiled areas along the northern Gulf of Mexico during the winter following the 2010 Deepwater Horizon oil spill.

Methodology: Specimens of scaup (Aythya spp), buffleheads (Bucephala albeola), and redheads (Aythya americana) were collected from local hunters to make comparisons of isotopic carbon signatures (n = 31, n = 6, and n = 12 total for scaup, bufflehead and redheads, respectively), a measure previously used to indicate oil hydrocarbon incorporation into tissues, using elemental analysis-isotope ratio mass spectrometry (EA-IRMS). A subset of these samples was analyzed for liver hydrocarbon concentrations using Gas Chromatography / Mass Spectrometry (GC / MS).

Results: Although based on a small sample size, we found little evidence of assimilation of hydrocarbons in waterfowl was detected based on isotopic signatures or liver concentrations with the exception of one redhead that had liver concentrations of 46 µg/kg Benzo[k]fluoranthene.

Conclusion: We speculate on possible explanations for the lack of oil indicators in waterfowl tissues including the rapid incorporation of oil into alternate food web pathways, degradation of oil prior to arrival, patchy oil distributions, low sample size, and/or insensitive metrics.