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
Largest shipwrecks on the Great Lakes Largest shipwrecks on the Great Lakes The Great Lakes are the largest bodies of freshwater in the world. They are five giant freshwater lakes, named Lake Superior, Lake Huron, Lake Michigan, Lake Erie and Lake Ontario. Thousands of vessels have sailed on the lakes from the late 15th century to the present day. Thousands of ships sank on the lakes from 1679 when "LaSalle"'s wooden barque the "Le Griffon" was lost, to the 1975 sinking of the giant freighter "Edmund Fitzgerald" on Lake Superior. Many of these shipwrecks were never found, so the exact number of wrecks will never be