After the Spill: Oysters and Oil Consumption
November 29, 2012
Oysters are a benchmark commercial species harvested along the shores of lower Alabama’s Gulf Coast. After the Deepwater Horizon Oil Spill of 2010 dumped almost half a million tons of crude oil into Gulf of Mexico waters, fishermen and consumers were concerned about the status of local oyster beds. In a recent paper in Environmental Science & Technology, Dauphin Island Sea Lab marine scientist Dr. Ruth Carmichael and colleagues questioned whether oysters consumed some of the oil, potentially helping to remove it from the local ecosystem and into the food web.
“We were fortunate to have been working on oysters along our coasts well before the DWH event,” said Dr. Carmichael. She and her colleagues were able to use oysters sampled before, during and after the spill to define how the oysters’ diet changed due to the oil spill and determine the potential contribution of oil-derived materials to oyster nutrition. They were able to detect distinct signatures of a typical diet, as well as one that would have signaled consumption of oil.
Oysters are filter feeders that remove particles from the water so that their shell and soft tissues reflect local environmental conditions. “Oysters can be powerful recorders of environmental changes, particularly changes in food sources and water quality,” said Carmichael.
The research team used stable isotopes and other biochemical techniques in oyster shell and meats and found that while oysters may have been exposed to oil, they actually consumed very little in their diets.
“Whether the oysters avoided eating the oil material or were not significantly exposed to accessible forms, we’re not sure. What we DO know is that the natural background diet was the dominant food source to the oysters we tested before, during, and after the spill,” stated Carmichael.
Environ. Sci. Technol., DOI: 10.1021/es302369h
Publication Date (Web): November 6, 2012