A University of Connecticut researcher and his team have discovered that a species of tiny aquatic organism prominent in harmful algal blooms sometimes called "red tide" is even deadlier than first thought, with potential consequences for entire marine food chains.
Professor Hans Dam and his research group in the school's Department of Marine Sciences have discovered that the plankton species Alexandrium tamarense contains not one but two different types of toxins, one that's deadly to large organisms and one that's deadly to small predators.
"If it's killing multicellular animals with one toxin and small protists with another, it could be the killer of the ocean world," he says.
Dam speculates that this ability to harm both large and small oceanic predators could lead to disruptions in the marine food web during large Alexandrium blooms, like the red tide that occurred along the Northeast coast in 2005, severely affecting the Cape Cod area.
"These small predators that are being affected by the reactive oxygen species are the things that typically eat large amounts of the algae and keep them from growing like crazy," says Dam. "This brings up a whole new line of inquiry for us: What will actually control these algae in the future?"
In small numbers, Alexandrium are virtually harmless to humans, says Dam. But when they're eaten by other clams, mussels or other microorganisms which are then eaten by small crustaceans, which are in turn eaten by larger crustaceans or fish the toxins can build up in large amounts. So in some parts of the world, eating contaminated shellfish, such as lobsters, clams and fish, has led to illness or death.
However, says Dam, that toxin only affects animals that have central nervous systems.
"This toxin blocks sodium channels in anything that has a well-developed nervous system," he says. "But most of the organisms in the ocean are not those kinds
|Contact: Tom Breen|
University of Connecticut