OLYMPIA - Emergency action will be taken Saturday to eradicate an invasive marine species that was discovered recently in Puget Sound waters off Edmonds. The species could potentially pose a serious threat to Washington state's diverse marine life.
Recreational divers in the Edmonds Underwater Park found a 30-square-foot growth of "colonial tunicate" in early October. The siphon-feeding animals form dense mats made of many thousands of individuals, suffocating existing sea life, including clams, mussels and other native species.
"Colonial tunicates attach to any hard surface available and can quickly spread throughout the area," said Pam Meacham, assistant invasive species coordinator for the Washington Department of Fish and Wildlife (WDFW). "It is important to take aggressive steps to eradicate this fast-growing, non-native organism as quickly as possible."
Scientists are becoming increasingly concerned about the impact that invasive species can have on Washington's native fish and wildlife populations. For example, European green crab, an aggressive shellfish predator, have been found in Washington's coastal waters for the past six years and threaten Washington's multi-million-dollar clam and oyster industries.
Divers have secured a plastic tarp over the colonial tunicate mass in the Edmonds Underwater Park. On Saturday, divers will return to the site and place chlorine tablets under the tarp in an effort to kill the colonial tunicate. Divers will also examine the surrounding area for signs of additional tunicate masses.
WDFW and the state departments of Ecology, Agriculture and Natural Resources worked together to expedite issuance of the water and pesticide treatment permits necessary to eradicate the colonial tunicate.
Water quality testing will be conducted at the treatment site during the eradication process.
Meacham said it is uncertain how the colonial tunicate came to western Washington, but it most likely came inadvertently via ballast water from a ship. The species is native to Europe, but it has also been found in San Francisco Bay and in areas off the eastern coast of the United States. It has no known predators.
The colonial tunicate discovery comes at a time when the Washington State Legislature has directed state agencies to develop a "rapid response plan" to address discoveries of invasive species.
"While this process has not yet concluded, the discovery of the colonial tunicate required rapid action," said WDFW Director Jeff Koenings. "We appreciate the efforts from the state departments of Ecology, Agriculture and Natural Resources, as well as the City of Edmonds to address this problem."
For more information and photos of the colonial tunicate, see http://woodshole.er.usgs.gov/project-pages/stellwagen/didemnum/ on the Internet.