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Images: Are Sea Squirts Crowding Out Scallops?

Meadows of eelgrass provide crucial nurseries for sea life and are a prime habitat for prized shellfish—bay scallops. Now, WHOI researcher Mary Carman has found areas where invasive species of sea squirts are growing on eelgrass and taking over former scallop territory. (Photo by Dann Blackwood, U.S. Geological Survey)

Researcher Mary Carman did a double take this summer when she spotted two sea squirts, known to scientists as Didemnum vexillum and Diplosoma listerianum, clinging to acres of underwater eelgrass in a pond and lake on Martha's Vineyard. (Photo by Amy Nevala, Woods Hole Oceanographic Institution)

An orange sea squirt called Botrylloides violaceus shares space with a young scallop on blades of eelgrass found in Sengekontacket Pond on Martha's Vineyard. (Photo by Amy Nevala, Woods Hole Oceanographic Institution)

Volunteers Peter Estrella (left), the deputy shellfish constable out of Oak Bluffs, and shellfisherman Jeff Clements help Mary Carman (in water) map the spread of sea squirts in Sengekontacket Pond on Martha's Vineyard.  (Photo by Amy Nevala, Woods Hole Oceanographic Institution)

An example of Didemnum vexillum, which Mary Carman found clinging to eelgrass in water bodies on Martha's Vineyard.

(Photo by Dann Blackwood, USGS)

An example of Diplosoma listerianum, which Carman also found attached to eelgrass.

(Photo by Dann Blackwood, U.S. Geological Survey)