Invasive species in the Wadden Sea


Botrylloides violaceus

From GiMaRIS in the Netherlands:

In three weeks time 28 non-native species are found of which twelve are new to the Dutch Wadden Sea. Some of these species like Botrylloides violaceus, which is introduced from the NW Pacific, are very brightly coloured.

Botrylloides violaceus is a sea squirt. Like Didemnum vexillum, another new Wadden Sea species. Also two Japanese crab species, including the Asian shore crab, were discovered for the first time ever in the Wadden Sea.

Source: NRC Handelsblad daily, paper edition, 22 September 2009, page 8.

Invasive Alien Species, ranging from disease and plants, to rats and goats, are one of the top three threats to life on this planet, according to a new publication coordinated by the Global Invasive Species Programme (GISP), of which BirdLife International is a partner: here.

The sea squirt offers hope for Alzheimer’s sufferers: here.

What Sea Squirts Can Teach Us About the Heart: here.

About these ads

4 thoughts on “Invasive species in the Wadden Sea

  1. * DECEMBER 3, 2010, 6:34 P.M. ET

    Invasive sea species may bring pros with its cons

    Associated Press

    BOSTON — An invasive sea squirt is increasingly being found spread like batter on the ocean floor off New England, but new research shows that’s not all bad news, despite fears about damage the animal could cause.

    The sea squirt rapidly expands on hard ocean bottom in rope-like chains or mats, and scientists worry it could crowd out valuable species that live on or near the sea floor, such as scallops.

    But new evidence shows some sea life and the fish that eats it actually thrive in regions where the sea squirt has taken hold. It’s an unexpectedly positive spin to the intrusion of a species scientists acknowledge they don’t fully understand.

    “This seems to be like the ecosystem is just sort of (saying): ‘OK, if you’re able to withstand that and survive here, then you might actually find it favorable and benefit to some degree,’” said Brian Smith, a federal food web ecologist who’s studying how the sea squirts are affecting groundfish diets.

    “Sea squirt” is the common name for various species, including the invasive Didemnum vexillum. Found worldwide, this species likely made its way to New England in the 1970s or 1980s in shipments of shellfish from Japan, said Judith Pederson, a scientist with the MIT Sea Grant program.

    The animal, since found south to Long Island Sound, looks like a tiny tadpole in its youngest stages, but is similar to a sponge as an adult, with a firm, flexible outer covering. The animal reproduces after fragments break off and attach to hard surfaces, forming colonies said to look like pancake batter.

    The sea squirts didn’t get much local attention until they were discovered in 2002 in a seven-square-mile patch of northern Georges Bank, the rich fishing grounds about 60 miles east of Cape Cod. Scientists have since found it in three areas of Georges Bank totaling about 180 square miles so far, though it doesn’t appear to be nearing domination of the vast 26,000-square-mile area.

    Much of Georges Bank has a sandy or shifty bottom where the sea squirts can’t get a firm grip, and they also appear to recede when the waters get colder.

    Still, the hard, gravelly areas where the sea squirts flourish are also a prime environment for scallops and important groundfish species, such as cod, haddock and flounder. Pederson said the sea squirts can perhaps harm scallops by growing over them, and also appear in preliminary studies to create an inhospitable environment for young scallops to take hold. The general aggressiveness of the sea squirts is also a concern, Pederson said.

    “In places where you see this animal, it can be the most abundant animal out there, which means all of your native species have been sort of reduced greatly in population size,” she said.

    But Smith’s work found that some animals are thriving among the sea squirts, including two species of marine worms and a species of Cancer crab that also appears to like the habitat created by the sea squirts.

    The worms are a known favorite of the winter flounder, a struggling groundfish species that slurps the worms up like spaghetti, said Smith, who works at the Woods Hole Laboratory of the National Oceanic and Atmospheric Administration’s Northeast Fisheries Science Center.

    Smith hesitates to call the findings about sea squirts “good news,” because so little is known about the long-term affects of a species that could still prove to have far more cons than pros.

    “It’s not completely negative,” Smith said. “Maybe that’s a better way to put it.”

  2. Pingback: Chinese deer in England | Dear Kitty. Some blog

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s