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
Great Lakes nations maintain coast guard vessels in the Great Lakes. During settlement, the Great Lakes and its rivers were the only practical means of moving people and freight. Barges from middle North America were able to reach the Atlantic Ocean from the Great Lakes when the Welland canal opened in 1824 and the later Erie Canal opened in 1825. By 1848, with the opening of the Illinois and Michigan Canal at Chicago, direct access to the Mississippi River was possible from the lakes. With these two canals an all-inland water route was provided between New York City and New Orleans. The