Bivalves such as oysters assimilate environmental toxins into their body when filtering water.
What happens to an oyster on antidepressants? What about on caffeine? Or, what if you combine these contradictory drugs and then consume the oyster?
As odd as it sounds, this scenario is playing out along the Oregon coast where oysters and other bivalves—a staple food source for both humans and animals— are assimilating low levels of environmental contaminants into their body. Portland State University researcher Elise Granek and colleagues are studying which chemicals are present, where, and what the effects may be up the food chain.
“The work in our lab is looking at how land based contaminants are affecting marine and coastal animals.” Granek said. “In the long term, what are the effects on humans?”
Bivalves—two-shelled animals such as clams, mussels and oysters—are integral to coastlines for food and structure. Not only do they serve as prime dining for many animals, but their colonies also provide shelter for small fish and invertebrates to hide. Bivalves filter water to feed, and thereby ingest a variety of chemicals from the water.
Granek and her team sampled native oysters at two sites along the Oregon coast to get an idea of what chemicals were present in their tissues. The results were stunning: ibuprofen, anti-inflammatory drugs, antihistamine and more. While each of these drugs was present in levels not considered harmful to humans, Granek is concerned about what the combined impact might be.
“These organisms don’t just have one compound. They have 2, 3, 4 types in them,” she explained. “So what happens when you have multiple of these compounds in one organism? How does that affect that organism or how does it affect predators that eat them, including us? We just don’t know.”
These contaminants likely seep into the water from outdated septic tanks or sewer overflows during storms and other high-water events.
Back in the lab, the team is conducting 90-day controlled experiments on each drug to get a better idea of the physiological effects on the bivalves. After they create a baseline for individual drugs—as early as spring—the lab will start combining different drugs to assess the effects.
“Most people who use pharmaceuticals or personal care products may not have any knowledge that what goes down the drain could harm aquatic and marine life,” said Joey Peters, a graduate student conducting the lab experiments. “I hope the results of this project elucidate one small piece of a growing problem.”
The next step is going back into the field to monitor which chemicals are present in other bivalves. From there, Granek wants to begin evaluating human impacts of eating these contaminated species. That information, she says, will help inform policy.
“My perspective has changed since I had a kid, and I think about all of the contaminants that she is exposed to in our world. Some things are harder to control and some things are easier to control. Food ought to be something that is easier to convince policy makers and managers to protect.”
Learn more:
- Emerging Contaminants in Oregon Coastal Waters: Landscape Drivers and Synergistic Effects on Native Oysters (Current Sea Grant-funded research project)
- Expression of HSP70 in Mytilus californianus following exposure to caffeine – 2011 journal article
