[November 17, 2009]

Chance to predict, prevent red tide?: Researchers: Iron key to blooms that damage clams

Nov 17, 2009 (Gloucester Daily Times - McClatchy-Tribune Information Services via COMTEX) -- Researchers are claiming a breakthrough in the understanding of red tide-causing algae that could help predict -- and, in the future, possibly prevent -- the blooms that wreak havoc on shellfishing communities nearly every spring.

In a federally funded study, a group of government and university scientists found that certain bacteria occurring in red tide blooms convert iron, a critical nutrient, into a form red tide plankton can absorb.

The symbiotic relationship between the bacteria and the plankton -- the plankton produce organic matter eaten by the bacteria -- builds as blooms grow larger and larger.

And understanding that relationship should improve the computer models that scientists use to predict where red tide blooms will be and how bad they will be, said William Sunda, a plankton expert and co-author of the study.

"One of the things we need a better handle on are understanding bloom dynamics and right now this sort of symbiosis isn't in the models," said Sunda, of the National Oceanic and Atmospheric Administration's Beaufort Laboratory in North Carolina. "We would be want to be able to forecast blooms like you can forecast weather." Exactly how the new understanding of the symbiotic relationship can be exploited to predict red tide is not yet known, and will probably start with the introduction of new variables in the computer models.

Sunda said it will take more research to find out whether there is a direct correlation between iron content in a body of water and algae growth.

Prevention of red tide will require an even greater leap.

Killing bacteria with antibiotics would likely come with too many indirect effects to be employed on a large scale.

Molecular engineering could hold promise for altering the iron-producing bacteria to stop the blooms, Sunda said, but those ideas are "down the road a bit." But even if it doesn't result in an immediate red tide preventative, or predictor, the new understanding of phytoplankton -- which exist in many nontoxic forms throughout the world's oceans -- could hold broad implications.

While seeing the end of red tide-causing plankton would likely be viewed as a good thing, the loss of other plankton could have negative impacts as well, including implications for global warming. Plankton play a key role in producing aerosols that lead to cloud formation and clouds deflect earth-warming solar energy back into space.

With fewer plankton could come fewer clouds, Sunda said, and fewer clouds could lead to higher temperatures.

If consumed in high enough quantities, the algae that make up red tide can cause paralytic shellfish poisoning in humans.

Plankton accumulate in filter-feeding shellfish, so when levels of the microrganisms are detected at certain levels, regulators ban the harvesting of bivalves in those affected areas until tests show the water is clear.

Last year, the state Division of Marine Fisheries estimated that the red tide outbreak in Massachusetts caused a loss of $1.2 million in direct revenue to shellfish harvesters, a good chunk of it in Cape Ann's soft shell clam market.

Including related businesses, the entire shellfish industry in Essex County has been estimated to generate as much as $30 million.

Patrick Anderson can be reached at 978-283-7000 x3455 or panderson@gloucestertimes.com To see more of the Gloucester Daily Times or to subscribe, go to http://www.gloucestertimes.com/. Copyright (c) 2009, Gloucester Daily Times, Mass. Distributed by McClatchy-Tribune Information Services. For reprints, email tmsreprints@permissionsgroup.com, call 800-374-7985 or 847-635-6550, send a fax to 847-635-6968, or write to The Permissions Group Inc., 1247 Milwaukee Ave., Suite 303, Glenview, IL 60025, USA.

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