Oyster Contaminants

Full Title: Use of elemental signatures to detect and trace contaminant entry to the northern Gulf of Mexico coastal food web: managing multiple stressors

This project will test whether trace elements associated with oil can be detected in oyster shells and serve as an indicator of oil exposure thus providing resource managers with a way to detect past oil exposure on oyster reefs.

Figure showing three restored oyster reefs (red circles) that will be sampled in the oyster contaminant research.

The Team: Ruth Carmichael (Lead Investigator, Dauphin Island Sea Lab, University of South Alabama, rcarmichael@disl.org)

Technical Monitor: Dennis Apeti (dennis.apeti@noaa.gov)

Federal Program Officer/Point of Contact: Frank Parker (frank.parker@noaa.gov)

This project began in June 2017 and will end in May 2020.

Award Amount: $231,671

Why we care: Oysters can serve as a record of water conditions at a particular site because they are stationary filter feeders with a hard shell that incorporates elements from the surrounding water as it continually grows. By measuring how trace elements associated with oil exposure are incorporated into a living oyster’s shell, the investigator will provide resource managers with an approach to detect when an oyster is exposed even after the oil is no longer present.

What we are doing: This study will test whether current or past exposure to contaminants may have affected the status of restored oyster reefs in Alabama, Mississippi, and Louisiana.These experiments will make it possible to link the chemical fingerprint in oyster shell back to exposure of that oyster to a contaminant. Because oysters live in waters that vary in salinity, particularly on the Northern Gulf of Mexico coast, where freshwater discharge can be very high, this link will be tested under different salinities. Understanding this linkage will make it possible to use historical oyster shell and tissue samples to assess past contaminant exposure at different sites. The trace element profiles in the shell of oysters exposed to contaminants will also be compared to measures of the biological condition of the oyster, such as growth rate, to develop an indicator for the condition of oysters at a particular site following contaminant exposure. Using data on mortality and abundance at active oyster restoration sites, this project will also assess whether current or previous exposure to contaminants is related to the status of a restored reef.

Expected Outcome: Overall, the results of this work will benefit the recovery of oyster reefs and the economic and ecosystem services they provide by determining how past oil contamination has impacted current oyster health in the Northern Gulf of Mexico.

From the seminar “Eastern Oysters (Crassostrea Virginica) as Retrospective Bioindicators of Trace Metal Contamination” 
Presenter: Dr. Ruth Carmichael, Dauphin Island Sea Lab, University of South Alabama