Killer seaweed hits California

Marine biologists are trying to save California's sea floor

By Toby Murcott of the BBC Science Unit

A seaweed that devastates marine life has been found for the first time off the coast of California.

The seaweed smothers marine life

It may look pretty in indoor aquariums, but caulerpa taxiflora has turned vast areas of the northern Mediterranean seafloor into a green desert.

Now biologists in the US are working to save the environment of the Californian coast from the same fate.

A small patch of the weed has appeared in a lagoon, greatly alarming biologists who are attempting to wipe it out before it can spread.

Harmful chemicals

The weed, originally from the Caribbean, was imported to Europe and used as decoration for tropical fish tanks. Hardier versions were developed especially for this purpose.

It was accidentally released from an aquarium in Monaco and a patch one metre square was seen in the Mediterranean in 1984. It spread extremely rapidly and now covers many hectares of seafloor.

While not toxic to human beings, it releases chemicals that can harm marine animals and it simply smothers the seafloor wiping out the local species of seaweed.

US marine biologists believe the Californian release took place when someone emptied a fish tank into a storm drain.

The scientists are confident they can eradicate this small patch, but are concerned that more of the weed is lurking in other aquariums. It seems only a matter of time before there is another release.