Cyanobacteria is the oldest known fossils onearth, which can be dating back to more than 3.5 billion years ago. Most cyanobacteria are photosynthetic, whichcontains large number of chemical elements. Cyanobacteria are also veryimportant in the nitrogen cycle because it is able to transfer atmosphericnitrogen into organic nitrogen, which are significant to most plants growth.
However,excessive cyanobacteria, which we called cyanobacteria blooms, is consideredharmful to the whole aquatic ecosystem. Specifically, as cyanobacteria becomeincreasingly dominant in a lake, the concentration of TP and TN also increase andthese all will lead to lake eutrophication. Besides all that, cyanobacteriablooms will also cause bad odor in a lake and it will deplete the availableoxygen and lead to anoxic conditions. Because of these damages, some governmentmade policies to regulate the environment of some contaminated lake and broughtwater to normal conditions after couple of decades by removing excessivecyanobacteria.