A Virginia Institute for Marine Sciences study has found that oysters reduce destructive parasite that attack blue crabs. In our weekly series with the Bay Journal Delmarva Public Media's Don Rush talks with reporter Lauren Hines-Acosta about the potential for the study's findings.
RUSH: A new study finds that oysters appear to filter out a particular parasite that kills numerous blue crabs each spring. This is Don Rush. Virginia Institute for Marine Sciences says they removed as much as 60% from the water on average per hour. In our weekly series with Bay Journal, we talk with reporter Lauren Hines-Acosta.
HINES-ACOSTA: A study recently came out from the Virginia Institute of Marine Science and they found that oysters filter more than just pollutants in water, but also certain parasites that tend to infect the Chesapeake Bay, like beloved Blue Crabs. Some researchers went out in these coastal bays along the Eastern Shore (although this parasite also lives at the mouth of the Chesapeake Bay) to test this theory, and they did find some effectiveness. The trials in the field showed that the crabs were a third less likely to become infected when they were next to these oysters.
RUSH: So in terms of how effective is this, what kind of findings did they have there... in terms of their ability to actually filter these things out?
HINES-ACOSTA: They did two sort of experiments. So in the field, they found that the crabs were a third less likely to become infected when they were sandwiched next to oysters and these special mesh cages they had made. But there's a lot of variables [like] hydrodynamics; they couldn't control everything, so they wanted to make sure that the oysters were playing a role in the way they thought. And so in the lab they did 10 trials of putting parasites in the water with the oysters, and they found that the oysters removed 60% of the parasites from the water per hour on average.
RUSH: What kind of losses do they incur in terms of the blue crabs?
HINES-ACOSTA: So this parasite, Hematodinium perezi kills a lot of blue crabs every spring through fall, and it's the worst in the summer. So that results into the Virginia fishery losing about $500,000 to a million dollars per year. The big takeaway from this paper is pretty much we're seeing the oyster population in the Chesapeake Bay is about one to 2% of what it was before overharvesting and disease that really took hold in this region about a century ago. And so the researchers from this paper argue that the decline in oysters could have contributed to the increase of infected blue crowds because they're not around in the same numbers to help save off that parasite.
RUSH: Is there any plan for trying to maybe do more of this? What goes beyond this study? Or do we know?
HINES-ACOSTA: Well, I know the researchers are hoping to explore what role restoring oyster reefs can play and maybe being strategic about maybe restore these reefs next to where we know blue crab populations are, or to be strategic about it. But the research want to take the first step and analyze if that's even accurate, reef scale. But as for addressing the parasite, I'm not quite sure what advocacy there is out there, but this is an active field of study.
RUSH: Bay Journal reporter Lauren Hines-Acosta on an oyster study that finds they filter out a particular parasite that kills blue crabs. This is Don Rush for Delmarva Public Media.
