Relates how in the late 1980s, French marine biologist Prof Alexandre Meinesz of the University of Nice-Sophia Antipolis first detected the spread of a new species of algae off the coast of Monaco. The algae (Caulerpa taxifolia), which is prolific and vigorous, drives out all other marine life and is so toxic no native creature can eat it. Colonies of the algae spread along the French Riviera and there are now pockets as far afield as Majorca, Sicily and Croatia. When the so-called `killer algae' was found in California, the authorities used chlorine gas, which kills all life, to ensure its eradication. Other contributors to the programme include: marine biologist Rachael Woodfield, Greig Peters of the California Regional Water Quality Control Board, Robert Hoffman of the National Marine Fishery Service, Prof Charles-François Boudouresque of the University of the Mediterranean, Marseilles, Dr Georg Pohnert of the Max Planck Institute for Chemical Ecology, Jena, Prof François Doumenge, Director of the Monaco Oceanographic Museum, Dr Thomas Belsher of the French Research Institute for Marine Development, and Olivier Jousson of the University of Geneva, a specialist in DNA sampling.