NB researchers monitor invasive tunicates

Posted on September 14, 2011


Lurking just across the St. Croix River, an invasive species with a deceptively innocent name has slowly been making its way toward New Brunswick, and it has some researchers worried.

The pancake batter tunicate, which resembles its namesake, blankets everything from docks to sea floors and poses a threat to the local ecosystem’s diversity, Jennifer Martin said. She is the lead researcher on a team of scientists and divers that will head to Campobello Island and Deer Island at the end of the month to spend two days monitoring the spread of the species that has been causing problems for north-eastern American states since it first snuck into the area aboard a mussels ship from Japan.

Tunicates, also known as sea squirts, are invertebrate filter-feeders that can largely carpet ocean floors. They usually move around by hitching a ride on something faster, such as a boat.

“It can smother and out-compete anything that is in our natural environment,” Martin said.

The researchers at the St. Andrews Biological Station have been monitoring the spread since 2009. At last inspection it was growing on pontoons and wharves in Eastport, Maine. They haven’t yet seen it in New Brunswick waters.

But Martin said it wouldn’t be a big jump to make. The two sides have nearly identical environments.

In late September, St. Andrews researchers will lead a diving expedition to Eastport, where they will study the invasive species to determine if there has been any progress since last year.

The researchers from St. Andrews Biological Station will be joined by counterparts from Halifax, Montreal and P.E.I., as well as some partners from the Woods Hole Oceanographic Institute in Maine.

This year will be their biggest team yet, at about 14 people in total, Martin says.

While species that get buried beneath its quarter-inch shell still seem to be able to breathe, the tunicate impedes growth. It can also latch itself to and weigh down fishing gear, aquaculture structures and buoys.

Unfortunately, Martin said there’s not a lot people can do once it’s there. They can scrape it off surfaces with a paint chipper, but this poses possible threat of spreading it further.

On Sept. 27 and 28, divers will go down during low tides, when the current is calm, to take photographs of the species and retrieve samples, which will be taken to the lab for study. They will also drag for scallops, which will likely haul up some of the tunicates at the same time, if present.

Tunicates can also be monitored by deploying collectors (plates) attached to floating docks or buoys.

In recent years, there has been increased efforts to study the invasion of aquatic species, as international trade expands and more vessels enter the Bay of Fundy.

To date, the Bay of Fundy tunicate monitoring program has provided evidence that the golden star tunicate, and the vase tunicate are present in the Bay of Fundy.

The pancake batter tunicate has been observed on the U.S. portion of Georges Bank and in northern Maine, including Eastport in Passamaquoddy Bay. But as Martin said, nature knows no political boundaries.

Previously published by the Telegraph-Journal; Sept. 1, 2011

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