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By DOUG FRASER STAFF WRITER Red tide threatens seabirds, whales
The spread of red tide slowed over the holiday weekend, with no new closures, but the bloom has intensified in Cape Cod Bay to the point where seabirds eating shellfish could sicken and possibly die, and even whales could be affected.A research vessel from the Woods Hole Oceanographic Institution and one from the Provincetown Center for Coastal Studies went out over the weekend sampling inshore waters to determine the intensity and extent of the bloom. In areas like Sandwich and Cohasset, the cells of Alexandrium algae that make up red tide are in full bloom, reproducing to the point where they reached unprecedented population levels in Cape Cod Bay of 40,000 cells per liter of water, 10 times anything that had been seen in the bay before. At that density, the water in Sandwich may start to turn red, one of the rare times that has happened in our waters.
''With scores that high in that area, we start to worry about seabirds and certainly humans,'' said Don Anderson, senior scientist at WHOI and a world-renowned expert in harmful algal blooms. Alexandrium cells produce a poison known as a saxotoxin that is concentrated in shellfish meat as clams, mussels and oysters feed on the algae. Eating shellfish with saxotoxins causes paralytic shellfish poisoning, with everything from numbness to paralysis and even death resulting.
Levels in shellfish can become so toxic that eating just a couple could be fatal to humans.
Wild Care in Eastham and the Cape Wildlife Center, which both tend to sick wildlife, had no reports of sick or dying birds over the weekend. Massachusetts Audubon Society naturalist Nancy Church said Audubon's Wellfleet Bay Marine Sanctuary did receive a call about an osprey that died soon after eating a fish.
''This is baby season, our busiest time of the year. To have potentially a mass mortality event is scary,'' said Wild Care director Lela Larned, State Division of Marine Fisheries chief shellfish biologist Michael Hickey said there was some concern for whales, particularly humpbacks, feeding on sand lances or mackerel that may have concentrated poison in their tissues after feeding on algae or smaller fish. Michael Moore, a WHOI scientist specializing in whale mortality, pointed out that red tide saxotoxin was blamed for the deaths of 14 humpbacks in 1987.
Sampling over the weekend showed Alexandrium cell counts at 4,000 per liter running along the coast from Barnstable on up through Truro, where it more than doubles to 10,000 in Provincetown. A normal reading this time of year without a true bloom might be 100 per liter of water.
This red tide bloom is possibly the largest in New England history, stretching from Maine down to the Cape and more than 20 miles east of Stellwagen Bank. The bloom was first noticed in early May off Maine. Currents would normally have taken the algae past Cape Ann on the North Shore and out to sea, but a northeaster May 7-8 blew the cells into Massachusetts Bay. A second northeaster May 24-27 pushed the bloom into Cape Cod Bay. Heavy rains from the two storms washed organic nutrients off the land into coastal waters that fed the bloom.
Add a weekend of sun over Memorial Day and you have perfect growing conditions.
Shellfishing was banned from Mid-Coast Maine to parts of Chatham, and back around the Cape tip into Cape Cod Bay to the canal. That left thousands of shellfishermen unable to harvest or sell their clams. Shellfishermen in Chatham, towns with Nantucket Sound beaches, and Nantucket and Martha's Vineyard were still able to earn a living digging clams and harvesting mussels and oysters.
Some good news
Anderson said there is some good news. Thus far, the canal has proven to be a barrier to the migration of mass amounts of algae. And, currents seem to be taking the bloom out to sea, skipping Monomoy Island, the heart of Chatham's $5 million shellfish industry. It might also bypass Nantucket.
In the meantime, shellfishermen, retailers and restaurants are making do with what they can get. Rick Angelini, owner of the Naked Oyster and co-owner of Grille 16, both in Hyannis, uses between 500 and 800 oysters a day. He's still getting local oysters from a Nantucket Sound aquaculturalist and from Nantucket and Chilmark.
If red tide ultimately closes those areas, he said he'll look down south or to northern Maine or Canada.
With red tide population levels up in the stratosphere, Angelini said he has faith in state DMF, emphasizing that because of rigorous testing and subsequent closures no one ever became ill or died since red tide first appeared in Massachusetts in 1972.
''Clearly, the real test was in the kitchen, where I popped a few in my mouth and ate them,'' he said.
Shellfish purge the poison from their systems in a few days or a couple of weeks after the algae have died off. One sign the bloom may be beginning to wane is that surveys over the weekend found Alexandrium cells that had moved into the next stage in their life cycle, just before they encase themselves in a hard shell and drop to the bottom. These cells develop into cysts only when food begins to run low or environmental conditions are no longer favorable and they wait out the summer on the bottom and hatch again in fall's cooler weather.
Rob McClellan, Wellfleet aquaculturalist and owner of Hatch's Fish Market, hopes he won't have to wait too long to sell local shellfish.
''If it lasts through the Fourth of July, it will be bad,'' he said. ''I couldn't see bringing in oysters from out of town, into this town.''
Doug Fraser can be reached at dfraser@capecodonline.com.
(Published: June 1, 2005)