Mussels and clams contaminated with poisonous algae blooms, known as red tide, have been found in the new Meadows River; prompting the state today to close the area to shellfish harvesting.

The earlier-than-normal outbreak of red tide in Maine could herald a hard year for the shellfish industry here, and a continuation of a global increase in oxygen-depriving algae-plumes, which are costing the fishing industry tens of millions of dollars.

Or, the early arrival of red tide might be the result of a warm, rainy spring, said Paul Anderson of the Maine Department of Marine Resources.

"Whether this means we are having a big red tide year, or if it’s just going to be limited to the typical hot points, we just don’t know yet," he said.

Anderson said the New Meadows River, between Bald Head in Phippsburg and West Cundy Point in Harpswell, will be closed to harvesting of mussels, clams and whelks until further notice.

No one can explain why red tide, brown tide and other oxygen-depleting algae blooms are on the rise around the world.

More than four tons of farm-raised salmon recently were killed in the country of Norway by an outbreak of algae not normally found in Maine; with the prevalence of international shipping, that species could be accidentally introduced to this country, Anderson said.

Senator Olympia Snowe, R-Maine, chairwoman of the Senate Sub-committee on Science and Fisheries, said the algae and toxic microbes such as Pfiesteria are costing the fishing industry $35 million to $65 million a year. "Even more troubling is that science cannot fully explain why this is happening or how to prevent it in the future," she said Wednesday during a hearing in Washington on the problem.

Last year an outbreak of Pfiesteria on two tributaries of the Chesapeake Bay attracted national attention, forcing the closing of the two rivers and killing thousands of fish. At least 39 people suffered health effects, from skin rashes to memory loss, according to federal officials.

Federal agencies and scientists have stepped up research in Pfiesterria and are trying to find ways to more quickly detect it in rivers and streams. Many scientists believe it is linked to nutrient runoff, including wastes from poultry farms.

With an El Nino-driven wet spring, federal officials say they’re bracing for summer outbreaks of more fish-killing algae blooms and harmful microbes.