Newswise — ITHACA, N.Y. – The shores of Appledore Island, Maine – just six miles from the New Hampshire coast – are being invaded by an aggressive red algae that can foul popular tourist beaches and damage vital local fisheries.
The seaweed, Heterosiphonia japonica, is a native to Japan and has not been reported elsewhere in Maine to date. The brownish-red stringy plant was first spotted underwater on Appledore in 2011 by undergraduates in the Shoals Marine Lab Underwater Research class. By this summer most of the studied intertidal transects on the island – permanent sites between the high- and low-tide lines – contained Heterosiphonia.
The alga grows in the water along the shoreline, then detaches and creates vast, decaying piles in the intertidal zone along the shore. In some locations along the Atlantic coast, Heterosiphonia has covered beaches and threatened tourism with its foul odor. Biologists are also concerned that this seaweed may out-compete native plants, overwhelming local ecosystems and the commercial fisheries they support.
Researchers believe this species was transported to the Atlantic Coast on boat hulls or by shellfish aquaculture. It was first discovered in southern New England on Rhode Island’s eastern seaboard in 2009.
So far, experts at the Lab – which is jointly supported by Cornell University and the University of New Hampshire – are cautious and say the impact of the red algae this far north has yet to be fully felt.
“It is currently present in large enough amounts in limited areas of Appledore’s shoreline to impact the intertidal zone. We don’t know what those impacts will be,” said Robin Hadlock Seeley, Shoals senior research associate. “Other than reports from lobster fishermen about clogged traps and troublesome piles of the seaweed on swimming beaches, we don't yet know the impacts of this seaweed invasion on the coast. But it's moving fast.”
The Shoals Intertidal Transect Project, begun 40 years ago when the Shoals Marine Lab was established, details the distribution and abundance of organisms in exposed and protected rocky intertidal habitats on Appledore Island. Through this annual survey of the biota of Appledore Island, Shoals Marine Lab, located in the Gulf of Maine, acts as a sentinel for invasive species expanding from the warmer waters of southern New England.
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