There is something lurking in the water

January 29, 1999

As scientists ponder the 'cell from hell' that is plaguing our oceans, Tim Cornwell asks, is pollution to blame?

Harmful algal blooms in the sea, often called "red tide", pose a growing threat in the coastal waters of much of the world. In the United States alone, they may be costing as much as $100 million a year in human death and illness, ecological damage, and mass die-offs of fish and shellfish.

In an "escalating and worrisome trend", most US coastal regions - from New England to California - are threatened by sea-borne algae, according to Donald Anderson of the Woods Hole Oceanographic Institution in Massachusetts and a father figure in this field of ocean science. "The United States is not alone. Nations throughout the world are faced with a bewildering array of toxic or harmful species," Anderson says.

Harmful algal blooms - HABs - have a long history. It is thought that red tide was one of the biblical plagues, prompting the biblical prohibition of the eating of shellfish. Homer described them in his Iliad. But they are still poorly understood, and scientists are now trying to get to grips with these bacteria living in our vast oceans. With many in the scientific community reporting that HABs are on the increase, humanity's role - particularly whether pollution is to blame - is the most pressing mystery.

Lora Fleming, an epidemiologist at the University of Miami, describes the sea as a vast soup, swirling with bacteria and algae that may become toxic at only one stage in their life-cycle. "How do you figure out what is going on out there?" she asks. "We have a long way to go."

One of the biggest contemporary puzzles surrounds pfiesteria piscida, discovered and identified by Dr JoAnn Burkeholder of North Carolina State University and tied to a fish die-off in Chesapeake Bay, near Washington DC. Her controversial work linking diseased fish in North Carolina's waterways to slurry running off from the region's farms has earned her the lasting enmity of local fishing and farming industries, who blame the reports of pfiesteria piscida for scaring off tourists.

But Burkeholder's "cell from hell" has been an elusive quarry and so has the sickness it has allegedly caused in fishermen and lab workers, loosely titled Estuarian Associated Syndrome, along with a variant, Possible Estuarian Associated Syndrome.

Anderson identifies a string of economic and public health problems traced to harmful algae. They run from paralytic, neurotoxic and diarrhetic shellfish poisoning in humans to the death of farmed salmon, scallop and mussel populations and the overgrowing of macroalgae and seaweeds.

Economic costs are difficult to measure, but one outbreak of paralytic shellfish poisoning cost the state of Maine $7 million. The development of a commercial shellfish industry in Alaska, where several people have died, has been barred. And in Long Island, New York, blooms of brown tide are blamed for devastating the bay scallop industry Nor should the "linkage to pollution be ignored", Anderson says. There is speculation that man has helped the spread of red tide by dumping waste in the seas - everything from nutrient-rich sewage to bilge water from cargo ships.

Disease from eating seafood is still heavily underreported. But in one of the most dramatic examples of how man helps disease travel, 75 people aboard an airplane flight from from Lima, Peru, to California developed cholera after they consumed a cold seafood salad plate.

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