This is Your Bay on Drugs

Balmer Sun (archive), Street drugs kill — even if you’re an oyster living in the Chesapeake Bay

Scientists administered drugs to oyster larvae in dishes to better understand how drugs found in surface waters near major cities like Baltimore and Annapolis affect wild oysters. They administered fentanyl, ketamine and benzoylecgonine — a cocaine derivative — that have been measured in marine ecosystems. “These drugs can be detected in surface water,” said lead researcher Gustavo Salcedo of the University of Massachusetts, Lowell. “The concentrations that we’re using attempt to recreate conditions that are detected in the waters around the world.”

The oyster larvae spent their days in water laced with drugs and were observed at eight days old and 14 days old. Salcedo and his team observed their swimming speed and patterns, survival and expression of certain genes. At both observation periods, survival of all drugged oysters declined compared to those living in clean salt water.

They originally planned to simply document survival rates, he said, but after the first few experiments, they noticed strange activity and stunted growth in the drugged oysters. “Swimming behavior is very important for aquatic organisms’ survival,” he explained. “It’s how they feed. It’s how they escape predators.”

Oysters at this stage usually swim in straight lines, Salcedo said. Those on cocaine and fentanyl spent more time swimming in circles, while those on cocaine and ketamine almost stopped swimming. Larvae on ketamine moved the slowest, and those on fentanyl actually swam slightly faster than the control group, but also spent more time swimming ineffectively in circles.

After two weeks, about 70% fewer oysters in the cocaine group survived, compared to the healthy oysters. They showed genetic activity indicating a fight against antioxidants, which Salcedo said indicates a struggle against damage and cell death. All of these deviations signal behavior that would lead to even higher mortality in the wild, he said, where other pollution and predators would further decimate the survivors.

Cocaine's for horses, not for men, they tell me it'll kill me but they don't say when. 

While the Chesapeake Bay Program has documented harm to the Bay’s oyster population due to microplastics and drugs or other “invisible” contaminants, Salcedo said the levels of street drugs ingested by oysters would not get a person high from eating them — if the drugged oysters survived to maturity.

The National Science Foundation funded the work, which was published in September in the journal Ecotoxicology and Environmental Safety. Salcedo presented their findings at the annual meeting of the Society for Risk Analysis in Washington, D.C., on Dec. 8.

Maryland waterways can host a cocktail of legal and illegal drugs, said Carys Mitchelmore, a professor at the University of Maryland Center for Environmental Science’s as well as the center for Anthropogenic Changes in Estuarine Systems. “Oyster populations face a barrage of pollutants — physical, biological and chemical contaminants,” Mitchelmore wrote in an email to the Baltimore Sun. “Regarding chemical contaminants, there are thousands out there. Some are more toxic than others, and so environmental risk assessments are conducted to prioritize those of concern.”

She said drugs get into waterways primarily from the people who use them, either leaching from individual septic systems or released from wastewater treatment plants that are often not equipped to clean up these chemicals. According to Maryland Department of the Environment sources, traces of drugs also are released from drug manufacturing facilities and seep out of landfills where people discard unused prescriptions and farm operations that use antibiotics to keep livestock healthy. “Wastewater treatment plants — depending on the level of treatment — can degrade some of these compounds, but not necessarily into less toxic compounds,” Mitchelmore said.