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A Drifting Exposure and Effects Assessment Ring.

In-Situ Bioassays: Assessing Oil Spill Toxicity to Aquatic Life in the Field

Bioassays, tests that expose animals to oil to measure the toxic impacts, are usually done in the lab with scientists attempting to recreate oil spill conditions. A new tool called a Drifting Exposure and Effects Assessment Ring (DEEAR) was developed to drift for 8-48 hours and perform bioassays in actual oil spills. This tool was tested in the natural oil seeps off the coast of Santa Barbara in 2019. 

Small shrimp, larval fish, and fish eggs (which are commonly used in such experiments) are contained within glass tubes that water, and oil from the environment are pumped through. Other sensors collect data on contaminant concentrations, water quality, and the DEEAR’s trajectory as it drifts. After the DEEAR is retrieved those animals can be taken to the lab to study how the oil impacts their health over time. This includes studying which animals are killed by the oil, and any negative health impacts (sublethal impacts) on those that survive. 

Why is This Research Important? 

Bioassays help scientists to understand the specific impacts of oil, at different concentrations, to living animals. These data helps researchers confirm that injuries to marine life observed after an oil spill were caused by pollution, and develop a better understanding of an oil spill’s impact on the larger ecosystem. 

Not only does this research allow for more environmentally accurate bioassay studies, future advancements of the DEEAR have the potential for scientists to track biological and chemical data in real time during an oil spill. 

The full study is available in the Journal of Environmental Toxicology and Chemistry, “Tracking and Assessing Oil Spill Toxicity to Aquatic Organisms: A Novel Approach.”

For More Information Visit: 


United States Environmental Protection Agency
University of Michigan
Coastal Monitoring Associates
University of New Hampshire
Water Mapping LLC



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