What may look from the air like a blazing oil slick can turn out to be a kilometers-long carpet of marine algae, their luminous bodies setting the ocean aglow. These outbursts of algal exuberance sometimes have a dark side: Algal toxins have been blamed for everything from fish kills in North Carolina to a manatee massacre in Florida to the 1987 deaths of four Canadians who consumed tainted mussels.
Anyone intrigued by toxic algal blooms--more commonly called red tides, although they're neither tide-driven nor always red--can turn to the eclectic Harmful Algae Page , started 4 years ago by marine ecologist Donald Anderson of the Woods Hole Oceanographic Institution in Massachusetts. To get a feel for what scientists are up against, start with the photos, a gallery of rogues that poison their enemies--such as the dinoflagellate Alexandrium tamarense--or stab them to death--including a Chaetoceros species that plunges its serrated spines into the gills of fish.
A section on human illnesses describes the five main kinds of algal seafood poisoning, which causes symptoms such as diarrhea and numbness. Illuminating the scope of the problem, a set of maps shows past algal blooms in U.S. coastal waters, and a short essay delves into why the number of blooms seems to be rising--better surveillance and nutrient-laden pollution are suspected. Researchers can search a directory of algal specialists, browse documents that spell out state, federal, and international research and control efforts, and access references and outside links.