DURHAM, N.H. — For the past 25 years, researcher Stephen Jones has tried to understand the threat that bacteria may pose to oysters in New Hampshire’s Great Bay estuary. He often couldn’t get funding to study the problem. But that is beginning to change as scientists notice “something is going on.”
Scientists are recognizing that a waterborne disease sickening tens of thousands of people each year is associated with warmer waters of the Gulf of Mexico moving northward, partly because of climate change. The problem is extremely rare in New Hampshire and neighboring Maine, but scientists have seen cases elsewhere in New England and expect it to become a bigger problem.
“We have this situation in the northern part of the United States and other cooler climates where people haven’t thought this had been a problem,” said Jones, of the Northeast Center for Vibrio Disease and Ecology at the University of New Hampshire. “In the last 10 or 20 years, it’s become very apparent that there is something going on.”
In a paper in the science journal PLOS One, Jones and other scientists reported their findings that illnesses from vibrio bacteria have jumped significantly in New England – from five cases in 2000 to 147 in 2013. Disease-causing bacteria can contaminate oysters, leading to infections such as diarrhea, vomiting and abdominal pain.
Jones and his colleague, Cheryl Whistler, concluded that warmer waters in the Great Bay, higher salinity and the presence of chlorophyll all contributed to higher concentrations of one of the more common vibrio species that makes people sick – vibrio parahaemolyticus. The researchers are hoping their findings will serve as the foundation of an early warning system for the region’s booming oyster industry.
Currently, all experts can do is monitor the waters and rapidly cool harvested oysters to halt bacteria growth.
“Eventually, we would want shellfish managers to have access to these models that would allow them to communicate to the growers that conditions have changed and that we now need this to manage the potential risk to reduce whether there will be exposures,” Whistler said.
The bacteria fueled by warmer temperatures are also a stark reflection of the impact that climate change is having on the world’s oceans, experts say. An August report in the Proceedings of the National Academy of Sciences found that warming waters were linked to waterborne food poisoning, especially from eating raw oysters.
“There is similar reporting in Alaska where it has been found that increased cases have been occurring where it has not been reported before because of the temperature rise,” said the study’s lead author, Rita Colwell, of the University of Maryland.
The industry has welcomed Jones and Whistler’s work, noting that outbreaks like the one that occurred last month in Massachusetts need to be avoided. Nearly 75 people were sickened.
“When you are involved with a recall because people have gotten sick, you are a losing tremendous amount of money and a tremendous amount of credibility,” said Tom Howell, president of Spinney Creek Shellfish Inc., in Eliot, Maine, which harvests oysters from the Great Bay. A predictive model would allow the industry to move more aggressively to avoid an outbreak, he said.
But Howell and Chris Nash, New Hampshire’s shellfish program manager, said that day could be far off.
“We are still learning what seems to trigger these pathogenic strains to multiply … We don’t have that knowledge yet and it may be that we never do,” Nash said. “We are talking about biological organisms … They react to their environment different, the same way humans do.”
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