December 05, 2016
Hampshire looks for answers behind oyster outbreaks
DURHAM - 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 due to 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 oyster 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 losing a 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