Harmful Algal Blooms: Biosensors Provide New Ways of Detecting and Monitoring Growing Threat in Coastal Waters

D eep in the southwest of Scotland ripples a pool of moss-green water.Soulseat Loch, as this small lake in the United Kingdom is known, glows with unearthly green water-green because pixies, or elves, once washed their clothes in the loch.Or so claim local legends.But scientists who have studied the loch's water, like Geoffrey Codd of Scotland's University of Dundee, believe there's another explanation for its green color: a bloom of blue-green algae."At certain times," explains Codd, "Soulseat Loch's waters are covered with a 'scum' of green material.This floating raft is an overgrowth of blue-green algae named Oscillatoria agardhii.Blooms of these algae can make the water toxic to people-or animals-who drink it."That's exactly what happened in 1994, when six cattle died from drinking the green water of Soulseat Loch.The cows exhibited signs of rapid-onset disease, according to the farmer who owned them,"and in fact were subsequently found to have partially brokendown filaments of O. agardhii, which was toxic to the animals' livers, in their rumens," says Codd. Soulseat Loch, local farmers maintain, has a history of annual blooms of blue-green algae.This red tide, or Noctiluca miliaris bloom, was sighted