Workshop to show: Shellfish diseases in
Bay warrant watchfulness, not panic
NARRAGANSETT -- August 17, 2000 -- Shellfish diseases that have
damaged crops of oysters and clams in neighboring states have made their
way into Narragansett Bay. But the situation calls for caution, not panic,
because there are only a couple of locations where concentrations of infected
shellfish are high.
This is the word from fish pathologist Marta Gomez-Chiarri, a University
of Rhode Island fisheries, animal and veterinary science assistant professor.
Gomez-Chiarri will report findings from a survey of locally identified shellfish
diseases in a workshop Thursday, August 24. The presentation begins at 6:30
p.m. at the Coastal Institute, URI Bay Campus, Narragansett.
While Gomez-Chiarri focuses on diseases found in Rhode Island waters,
Roxanna Smolowitz will contribute reports about Massachusetts shellfish
diseases. Smolowitz is a veterinarian from the Marine Biological Laboratories
in Woods Hole, Mass., who has researched QPX (quahog parasite unknown),
among other diseases.
The scientists hope to alert shellfish harvesters and aquaculturists
to infestations of parasitic diseases and to identify some of the conditions
that signal disease presence. They will open their presentations to audience
discussion of aquaculture, implications for fisheries, and management and
Gomez-Chiarri's comments will update findings from the ongoing Shellfish
Disease Survey Program, designed to map the incidence and intensity of various
shellfish diseases in local waters. With research funded by the Rhode Island
Department of Environmental Management's Division of Fish and Wildlife and
outreach support from Rhode Island Sea Grant, her work will guide decisions
by managers as well as harvesters and aquaculturists about where to harvest,
when to harvest, where to gather seed, and where to transplant cultured
Now in its third year, the survey targets two diseases-Dermo and MSX
(Multinucleated Sphere X)-both caused by single-celled protozoan parasites
and both affecting oysters. Dermo, Perkinsus marinus, kills by breaking
(lysing) oyster tissue when it proliferates to high numbers. The Dermo parasite
"loves warm temperatures," says Gomez-Chiarri, "so it proliferates
in summer to the point that the oysters can't keep up with it." MSX
infection kills fairly quickly by spreading throughout the oyster's tissue.
While not harmful to humans, according to Gomez-Chiarri, these parasites
can wreak havoc with oyster crops. MSX can be transmitted from oyster to
oyster, and Dermo can take as long as three years after infection to kill
its host, gaining ample opportunity to spread to healthy mollusks. In both
cases, a major path to infection is transplantation of healthy oysters into
infected beds or infected animals into clean beds.
Gomez-Chiarri notes that, even if there's not much fishermen can do
about disease, "if they know what places in the bay have problems,
they can harvest or they can get seed elsewhere."
For information about the survey, sites of infestation, other disease
organisms identified and their impact on shellfish, contact David Beutel,
URI fisheries, animal and veterinary science, (401) 874-7152.
# # #
Contact: Tony Corey, (401) 874-6844