Professor Attempts to Crack Mystery of Lobster Shell Disease

Posted: February 12, 2007 at 1:00 am, Last Updated: November 30, -0001 at 12:00 am

By Tara Laskowski

Patrick Gillevet
Patrick Gillevet
Photo by Evan Cantwell

In Long Island Sound and some parts of the coast of Maine, lobsters are dying because of a mysterious shell disease that is literally eating the lobster alive. The disease eats through the shell and prevents the lobster from molting, causing it to die.

The disease is not caused by a single “bad” bacteria, but rather by a biofilm of bacteria, a combination of different kinds of bacteria that form a “perfect storm” and cause the disease. This kind of disease, known as a polymicrobial disease, is what Patrick Gillevet, associate professor of environmental science and policy, has been studying and mapping for the past 10 years.

diseased lobster
Photo courtesy of Barbara Somers

According to a fact sheet prepared by the Rhode Island Sea Grant, researchers first noticed lobster shell disease more than 20 years ago. At that time, the disease appeared as little black spots affecting the lobsters’ shells. But in the past several years, shells have sometimes become fully infected by the disease, with the worst cases rotting the shells entirely. Thirty percent of lobsters in coastal areas of southern New England and Long Island Sound are now affected by shell disease.

With a new $2.3 million National Oceanic and Atmospheric Administration grant, the New England Lobster Research initiative based at the University of Rhode Island is coordinating researchers from 11 institutions across the country to try to understand and control the spread of the disease. As part of that effort, Gillevet and Jeffrey Shields, a collaborator from the Virginia Institute of Marine Science, are studying the microbial community of lobsters and how it affects this disease.

Using his patented technology known as Multitag Pyrosequencing, Gillevet is able to map all of the bacteria in the biofilm on lobster shells in an afternoon.

“This is 100 times faster that what is normally done – we can look at 500,000 bacteria in one run,” says Gillevet. “Before, it would’ve taken an entire year to characterize one biofilm.”

Using Multitag Pyrosequencing, Gillevet can look at the DNA sequences of all the bacteria on dozens of diseased lobster shells and determine the kinds of bacteria and the amount of each type of bacteria to see how it differs from healthy lobsters.

This information will help Gillevet determine what combination of bacteria is causing the disease and if this bacteria colony is the primary cause of the disease or a secondary cause due to outside factors (such as pollution or global warming.) Once these bacterial communities are fully characterized, he will be able to determine how the bacteria interact with each other and how they interact with the living substrate they are destroying.

Gillevet uses Multitag Pyrosequencing in other research projects. Working with Bob Jonas in the Department of Environmental Science and Policy, Gillevet is mapping the bacteria biofilm of diseased coral to determine how coral reefs are being destroyed in certain parts of the world.

“Polymicrobial disease research is already affecting medical applications,” said Gillevet. “We have done extensive work on Crohn’s disease and ulcerative colitis and have developed several basic scientific principles that apply just as well to lobster shell disease, coral diseases and human disease. This new understanding of shifts in microbial communities will lead to an understanding of the processes involved and possible treatments for these diseases.”

lobster with disease pointed out
Photo courtesy of Barbara Somers

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