Cyanotoxin which is why they are usually green or blue. Cyanobacteria are found almost everywhere; in oceans, lakes and rivers as well as on land. They flourish in Arctic and Antarctic lakes, hotsprings and wastewater treatment plants. They even inhabit the fur of polar bears, to which they impart a greenish tinge. Cyanobacteria produce potent toxins, but they also produce helpful bioactive compounds, including substances with antitumour, antiviral, anticancer, antibiotic and antifungal activity, UV protectants and specific inhibitors of enzymes. Cyanotoxins are often implicated in what are commonly called "red tides" or "harmful algal blooms". Lakes and oceans contain many single-celled
The Rise and Fall of the Great Lakes for theatrical distribution. However, Mason was disappointed when the NFB producer made several changes to his finished work, feeling he had lost creative control. The film won a BAFTA Film Award in 1971. The Rise and Fall of the Great Lakes The Rise and Fall of the Great Lakes is a 1968 Canadian short film featuring a humorous geography lesson, in which a canoeist travels abruptly through time as he crosses the Great Lakes, experiencing cataclysmic changes in different eras. The film is narrated in ballad form. Some animation is employed in the film to show the coming and going