Oceanographers and natural resource officials from four continents gathered at the Woods Hole Oceanographic Institution in Woods Hole, Mass., in April for a two-day conference to discuss a diminutive – if insidious – invasive species now creeping its way north along the U.S. and Canadian East and West coasts. The sea squirt, which 15 years ago did not exist in New England waters, now covers clam beds, pilings and jetties along both coasts. It has no known predators, according to WHOI scientists, and is known to exist in temperate waters in New Zealand and the Netherlands.
“It’s a global threat, and we don’t even know what species we are dealing with,” said Mary Carman, organizer of the first annual International Invasive Sea Squirt Conference, which was held April 21 and 22.
“Is it a species that has not previously been identified? Is it a species that has been described but we haven’t figured out which one? Or is it a newly evolved species?” Carman asked.
The filter-feeding didemnid, also known as an ascidian or tunicate, because of the tunic-like veil covering its body, is spreading rapidly and can grow from less than 1 inch to 3 feet long.