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SeaWeb Ocean Update: November 1999 Die-Offs Affecting Long Island Lobsters, Maine Urchins, Florida Dolphins
Three simultaneous mass mortality events are affecting divergent marine wildlife populations along the eastern seaboard and the Gulf coast. At time of going to press, the precise cause in all three cases remains a mystery.
In Maine, reports of dead and dying sea urchins on the sea floor and in tidal pools first appeared in mid-September, and accelerated following the opening of the urchin fishing season. It's unknown how extensive the die-off is; divers have reported finding urchins dead in areas where others nearby appear unaffected. Theories to explain the die-off include harmful algal blooms, marine bacteria, and a warm-water ameba. Although some researchers have suggested the die-off is not necessarily anything unusual or alarming, others beg to differ. "I started looking in the tide pools and there were a lot of urchins on their backs," said Peter Harvie of the University of Maine. "I've never seen a sick sea urchin, and I've been looking into tide pools for 20 or 30 years."
Mystery also surrounds a die-off of lobsters in Long Island Sound. Although the region regularly succumbs to episodes of hypoxia ? in which levels of oxygen drop in the water column, generally after algal blooms ? tests have shown that oxygen levels in the water are normal. The summer did witness relatively high water temperatures in the area, but this was mostly at the sea surface, not the bottom of Sound, where the lobsters live. Studies have shown the presence of two species of as-yet unidentified bacteria in some of the dead lobsters, but it is at present unknown whether either or both of these organisms are related to the die-off.
Meanwhile, more than fifty dead bottlenose dolphins have washed ashore along the Gulf coast of Florida since August. Tissue samples from the twelve most recently dead dolphins have been sent for analysis. Although no positive correlation between the events has been established, a red tide outbreak occurred in two Panama City bays in late August and September.
Sources: Haberstroh, J. 1999. A die-off of lobsters in the Sound: Mysterious ailment sweeping Long Island waters threaten a usually lucrative fall harvest. Long Island Newsday. October 17, 3; Richardson, J. 1999. What's killing the urchins? Portland Press Herald. October 10, 1.
Contact: Bruce McKay, SeaWeb. Tel: (514) 270 3978. E-mail: bmckay@seaweb.org
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