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
Rivers and lakes of Armenia ones include the Dzoraget and the Pambak. The following table is the list of the biggest rivers in Armenia: Armenia has one very large lake called Lake Sevan and more than 100 small mountain lakes. None of them, except Sevan and Lake Arpi, have yet been extensively studied. The water resources of the lakes amount to about , Sevan holding most of this, nearly (before the drainage it had almost ). At the country's capital, Yerevan, it is possible to find small lakes, often in amusement parks. Rivers and lakes of Armenia The Rivers and lakes in Armenia are mainly