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Don Anderson, Holding Back Red Tide

The ocean is teeming with plants, and most of them are good for marine animals and the planet as a whole. But as with anything in life, it is possible to have too much of a good thing. Biologist Don Anderson studies an insidious and sometimes fatal form of overindulgence: harmful algal blooms.

Algae are microscopic, single-celled plants that live in the oceans and many other bodies of water. Most species of algae (a form of phytoplankton) are plentiful, harmless, and incredibly valuable as the chief energy producers at the base of the marine food web, without which higher life on this planet would not exist.

Among the thousands of species of algae and phytoplankton in the sea, a few dozen produce toxins and pose a formidable natural hazard commonly called “red tides.” Sometimes they reproduce prolifically, discolor the water, and foul beaches with foam from their prodigious booms. Other times these harmful algae are dilute and invisible, nearly inconspicuous if not for the destruction they cause--a bloom of harmful algae can completely and permanently alter the structure of a food chain, causing massive die-offs of shellfish, marine mammals, fish, seabirds, and other animals that consume them. They can also sicken, disable, or kill humans who eat fish or shellfish that have ingested the toxic algae.

Don Anderson and his research colleagues are keenly interested in a toxic dinoflagellate known as Alexandrium, a genus responsible for poisonous red tides in many countries throughout the world. In 2005 alone, this harmful alga caused more than $50 million in lost revenues for New England’s seafood industry, as clam and shellfish beds from Narragansett Bay the Bay of Fundy had to be closed off to fishermen.

In the years since that dreadful bloom, Anderson and his team have been creating a regional observation and modeling program focused on the Gulf of Maine and its adjacent New England shelf waters. The project uses a combination of large-scale survey cruises on research vessels, autonomous underwater vehicles, moored instruments and traps, drifting instruments, satellite imagery, and numerical models to understand the dynamics, transport pathways, and toxicity of Alexandrium. They share this information with coastal managers, regulators, and fishing interests—and, most of all, the seafood consumer--to protect nearshore and offshore shellfish resources that can be threatened by paralytic shellfish poisoning. The researchers are even working to develop automated sampling instruments that could be left in the ocean to monitor the development of harmful algal blooms before they endanger the coast. Ultimately, Anderson and colleagues would like to be able to forecast algal bloom seasons in order to mitigate the impact on our coastal resources.

Originally published: June 29, 2007