The sea slime alarm was sounded in 2002. Scientists discovered small, dense mats of a strange gooey creature on the ocean floor more than 100 miles offshore. A year later, the sea squirts had carpeted more than 6 square miles there and kept going. Soon, the bizarre, stringy squirts were showing up in enormous colonies in new places along the shoreline and fishermen began complaining they were smothering shellfish beds.

State officials have surrendered any hope of slowing the sea squirts' goopy spread, which may be making the seafloor inhospitable to fish eggs. But they are determined to stop other marine invaders -- many of which hitchhike accidentally across the ocean on ships -- from establishing a foothold and harming fishing, tourism, or biodiversity.

Starting this summer, state officials will pay to train scores of volunteers to scour the state's beaches and peer at the underside of docks looking for any sign of invasive species. Armed with a marine Most Wanted list -- a deck of 20 laminated cards picturing likely invaders -- the volunteers will collect information for a database being developed with the Massachusetts Institute of Technology Sea Grant Program.

Officials hope the early discovery of potentially dangerous species will help the state mobilize a strike team to eradicate them.

"We know this is really hard and we're just beginning," said Beth Suedmeyer, invasive species specialist for the state Coastal Zone Management office.

Despite hundreds of documented marine invasions in the United States, officials have been able to contain only one: a fast-growing Mediterranean seaweed introduced into two California lagoons in 2000 that was killed with chlorine.

"We're hoping there will be opportunities to Poll ID stop does not exist. something . . . from moving up the coast in the future," Suedmeyer said.

Invasive land species have long been the scourge of gardeners and landscapers -- ask anyone who has tried to extract plants from the choking grip of an oriental bittersweet vine. This month, Massachusetts began banning more than 140 plants from being bought or sold in the state because they are threatening native species.

The freshwater zebra mussel that arrived in the Great Lakes in 1988 is the invasive species poster child, spreading to 20 states and reproducing so densely it clogs drain pipes.

One alarming estimate places the economic cost to businesses from invasive species as high as $100 billion a year, but scientists say no one has accurately isolated how much of that is from marine species.

What's hard enough to control on land or in lakes has been nearly impossible to identify in the sea's murky depths, where the animals are often out of sight.

Scientists say they believe most of the marine invasive species are sucked into ships' holds with tons of ballast water used to keep the vessels steady on voyages, only to be silently discharged half a world away into an environment where they may have few predators.

Scientists know of about 50 non-native species off New England's coast that they probably can't do anything about, including a European seaweed known as "dead man's finger" that arrived in the 1960s and is now being tied to the destruction of cod and sea urchin habitat.

The US Coast Guard began a mandatory program in 2004 to require all large ships traveling from overseas to exchange their ballast water with ocean water at least 200 miles from shore, where there will be fewer organisms to bring to a new port. Last month, the agency prohibited a Panamanian-flagged ship traveling from the Bahamas to Boston from entering the city's port until it went back out to sea and exchanged its ballast water because the ship could not prove it had done so. The ship did not have required records of when it took in and discharged ballast water.

But specialists say the invaders have many other ways to get here, such as attaching to the hulls of boats, or contained in deliveries of aquaculture, aquarium supplies, or live bait.

Scientists say some submerged invaders have probably been around since Colonial days and people may mistakenly believe they are native.

But in recent years, a series of invasions have gotten scientists' full attention. In 1992, a group of schoolchildren on a science trip in Woods Hole spotted an inch-long crab scurrying on the rocky beach. It was an Asian shore crab, and within several years it had spread to Boston. This summer, it reached Acadia National Park in Maine. Discovered in New Jersey in 1988, the crab eats almost anything it can find and scientists say it is forcing out native populations of mud crabs and might also be competing with lobsters or larger crabs for food.

The invasion news got worse with the sea squirt, which fishermen say looks like fast-spreading pancake batter. There are other kinds of non-native squirts off New England, but none is as feared as this kind, known as Didemnum. The animals are a kind of superorganism, able to reproduce both sexually and asexually so even a tiny fragment can form new colonies. Nothing eats them, and where they came from and when is unknown.

In 2000, scientists began assessing exactly what was in New England marine waters by descending on regions for a week at a time to count and identify species, but the program provides only a snapshot of the problem.

To help in the Bay State, Massachusetts gave Salem Sound Coastwatch, a local nonprofit, a grant of $10,000 in 2004 to develop a pilot program for average citizens to identify invasive marine species. Officials say they cannot expect citizens to identify all species -- even taxonomists have a hard time with that -- but citizens can identify certain foreign creatures that have caused problems elsewhere.

The Salem program trained more than 50 people, and this year state officials have about $20,000 to help train about five more nonprofit groups.

Now, state officials, along with a coalition of other New England officials and scientists, are trying to develop a plan in case they find a potentially dangerous invader. Possibilities include simply pulling the creatures out of the water or sand by hand and throwing them away, or using pesticides or parasites that can be targeted to the invasive species.

"The best approach is get them early because you don't know what is going to happen, " said David Delaney, a doctoral student at McGill University who is helping to create a network of citizen groups in the Northeast to identify invasive marine species. "It is roulette."

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Source: Knight Ridder/Tribune Business News