Saturday, July 30, 2005

The blob, underwater version

Fans of bizarre B-movies no doubt remember the movie, "The Blob," which starred Steve McQueen in his first major role and was shot largely in and around this particular part of the universe. (In fact, I know a couple of now-much-older folks who were extras.)
Well, if you believe the Red Star, the Blob, underwater style, is moving fast toward the Maritimes and Maine...
HALIFAX—The Blob is coming.
It is creeping across the ocean floor toward the Canadian border, covering one of the richest fish habitats on the continent with a thick layer of goo.
Two years ago, U.S. scientists discovered a novel little critter on an underwater shelf that is a cornucopia of sea life.
When they returned last year, they discovered the tiny sea squirt population had exploded, spreading over more than 100 square kilometres of the precious Georges Bank, about 200 kilometres south of Nova Scotia. In much of that area, a thick blanket of the tiny animals now covers half the sea bottom.
Page Valentine is one of the scientists who discovered the invasion two years ago. He doesn't like its many nicknames: the blob, the slime, the goo, pancake batter and macaroni. But he understands why the sea squirt has picked up so many horror movie monikers.
It is moving rapidly, little is known about it and it is invading an area at the economic heart of dozens of communities in Maine and Nova Scotia.
"This is a new thing on the bottom. We think it will have an impact, but we really don't know," says Valentine, a scientist with the U.S. Geological Survey.
He and others are careful not to sound too many alarms about the invasion. No one knows exactly what kind of threat the creature poses, but common sense suggests its presence on Georges Bank can't be good.
The scientific name for the invader is didemnum. It is a tunicate, a very simple animal that lives inside a skin, or tunic, has no skeleton and filters microscopic bacteria and plankton from ocean water.
There are many different types of tunicates. The ones on Georges Bank are colonial, which means millions of the things link together to form one vast blanket stuck to the seabed.
The tunicate will cover anything it encounters that isn't moving: clams, mussels, rocks, seaweed. Nothing will grow on top of it.
That means it gets between fish and their food, and may prevent scallop larvae from developing.
There is no evidence yet that the invasion on Georges Bank has hurt the commercial fishery, but that's one of the things the U.S. group will study.
Valentine is returning to the area next month to see how far the tunicates have spread in a year, and what kind of damage they have done to sea life.
"It hasn't been found in Nova Scotia, but it should like it there," Valentine says. "It may not have been found because people aren't looking for it."
Canadian officials have little to say about the tunicate explosion in offshore fishing grounds.
Neither the Bedford Institute of Oceanography nor the Department of Fisheries and Oceans have research projects dedicated to the new threat, nor any scientists who specialize in the area.
They do have scientists who have studied other types of tunicates, which have fouled aquaculture operations in Prince Edward Island and British Columbia.
Aquaculture is big business on the East Coast, a fast-rising industry that many hoped would replace traditional fishing as the focus of the rural economy. Mussels, oysters and salmon are raised around the Maritimes, and companies are experimenting with other species as well.
Mussel farmers in P.E.I., Nova Scotia and B.C. have battled tunicate invasions that took over their hanging farms. In some cases, the tunicates get so heavy on a line of farmed mussels that the mussels break off and sink to the ocean floor. In other cases, the tunicates smother the mussels, wrapping them so tightly that the bivalve can't breathe.
Even when mussels survive a tunicate invasion, they must be cleaned before they can go to market. According to Valentine, that process may be spreading the problem.
Tunicates reproduce several ways, but researchers recently discovered they can simply replicate themselves if torn apart. That means disturbing a tunicate colony could spread the colony, as the tiny particles drift with ocean currents.
That may be a problem on Georges Bank, where draggers regularly plough through the ocean floor searching for tasty scallops. Valentine says each pass by a drag boat may create a new infestation of tunicates somewhere else, as the animals are torn up and float away.

It's attacking the wrong areas. Show them the way to Hans Island, folks.
Maybe they will win the War of 2007.