Colossal oysters missing from parts of Florida's coastline

Modern oysters growing along northern Florida's Gulf coastline are significantly smaller than they were hundreds of years ago. Photo by University of South Florida
Modern oysters growing along northern Florida's Gulf coastline are significantly smaller than they were hundreds of years ago. Photo by University of South Florida

Feb. 6 (UPI) -- Northern Florida's Gulf Coast were once home to a large population of colossal oysters, but no more. New research suggests the once commonplace mollusks are now absent from even the most pristine stretches of Florida's coastline.

According to the latest study, published this week in the journal Biology Letters, the newest generations of Gulf Coast oysters are roughly a third smaller than their predecessors.


For the study, scientists collected oysters from some of the last remaining stretches of unspoiled coastline in northern Florida and compared them to prehistoric oyster shells recovered from dig sites near Crystal River, Florida.

"Most policy makers and conservationists working in this area are only considering the last 50 years -- when we first began actively monitoring these habitats," Gregory Herbert, geoscientist at the University of South Florida, said in a news release. "Using archaeological data, our work shows that what these systems looked like 100 or 1,000 years ago matters for conservation efforts now."

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Florida's Big Bend region, which comprises the eastern portion of the Florida Panhandle, is home to one of the last remaining natural oyster fisheries in the United States. Though often regarded as a pristine coastal zone, the latest research suggests the region's ecological health may be more degraded than previously thought.


"We've been altering the environment in Florida for a lot longer than the 1950's. So, if we don't look at a longer time scale, we might be missing the root causes of why fisheries and marine environments in our state are beginning to collapse," said lead researcher Stephen Hesterberg, doctoral student in integrative biology at USF.

In nature, size matters. As previous studies have shown, larger plants and animals play an outsized role in recycling nutrients and boosting ecological health. In the Big Bend region, larger oysters offer superior water filtration services and great reproductive success than their smaller peers.

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Oyster reefs with a greater abundance of offspring can recover more quickly from mass mortality events. Without the improved filtration services of colossal oysters, downstream estuary habitats are more likely to feature muddier water, stunting the photosynthesis and growth of sea grasses.

Researchers used isotopic geochemistry to study the biological changes in modern oysters. Their analysis showed modern oysters are just physically shorter, they're also living shorter lives and growing more slowly.

Authors of the new study hope their findings will help conservationists develop better oyster habitat management strategies. If wildlife managers can find ways to improve the ecological health of Florida's Big Bend region, it's possible the colossal oysters will return.

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