Sea Squirts Invade Georges Banks

[Charlie99]

An article in today's New Bedford (Mass.) Standard Times reports on the proliferation of tunicates in the Georges Banks.

Lead paragraphs:

A growing population of invasive sea squirts on Georges Bank could threaten commercial fish and sea scallop stocks by smothering their feeding and breeding grounds, according to scientists.
A new survey released yesterday shows that sea squirt colonies are spreading rapidly over an 88-square-mile study area in Georges Bank. Since last year, the area covered by the colonies has doubled at 75 percent of the observed sites, according to the survey.
Sea squirts are tunicates, or invertebrates that have a firm, flexible covering that resembles a tunic. They form thick mats when thousands of the tiny filter-feeding creatures attach themselves to gravel, ship hulls, docks and other hard surfaces. The squirts found on Georges Bank are known to scientists as a species of the genus Didemnum.

 

[archman]

That stuff's spreading all over. I haven't heard a peep from anybody regarding possible ways to get rid of it. Like most intrusives, all we ever seem to do is monitor it and whine about how bad its effects are.

Somebody needs to grow it in a lab and experiment with ways to kill the stuff.

 

[MarkH]

The problem (up here anyways) is that there are local species that look almost identical. With all the hype about invasive tunicates, I'd hate to see some well-meaning-but-dumb divers scraping the wall at Ten Mile Point bare.

 

[cummings66]

What's the name of your local species that's good? All I've ever come across is the bad stuff, but I did find it takes many tons of them to make 3 oz of cancer fighting drugs.

 

[MarkH]

What's the name of your local species that's good? All I've ever come across is the bad stuff, but I did find it takes many tons of them to make 3 oz of cancer fighting drugs.

I'm not sure what you mean by "good" tunicates, but we have dozens of local species. There are a few listed on the following page:http://www3.telus.net/kerryw/creature/creature.htm.
I don't think I've ever done a dive around here where I haven't seen at least a few species. There are some sites where large multi-coloured colonies cover the wall. Some of these tunicates (ascidians), such as compound, lobed and stalked look pretty much identical to invasive species on both coasts. I don't think a diver would be able to differentiate between local and invasive species unless they had a scientist who specializes in tunicates handy. Even then, some species are so similar you'd probably need a lab to make a proper I.D. I mentioned Ten Mile Point because that is one local dive site where there are piles of the lobed type which look pretty much like a tunicate that is carpeting some places on the East Coast. There are warnings about invasive tunicates in local dive magazines, websites and dive clubs which I think increases ecological paranoia in some divers and could lead to damage to innocent local ecosystems.

 

[archman]

Once an area's been destabilized by an intrusive exotic, mitigators are going to do collateral damage no matter what. Often a great deal of damage, at least in the short term.

Kill the tunicates!

 

[waterkitty]

They are working on ways in New Zealand to eradicate the tunicates. Right now, we are trying to understand their biology and get them growing in the lab to figure what makes them tick, the key to getting rid of them and uncovering other places to which they could spread.

 

[archman]

They are working on ways in New Zealand to eradicate the tunicates.

Got any details on the aussie stuff? Do they have some experiments in the works?

 

[waterkitty]

Oh shoot...I just came back to SB after months of deadbeatedness. The KIWIS - - are doing research on cost-benefit analysis of eradication at the Cawthron Institute. There is a report somewhere. I will have to get my mitts on it.

 

[Scram Bulleggs]

Is there a fish dying off that normally would use it as a food source?