The term algae encompass a variety of simple structures, from single-celled phytoplankton floating in the water, to large seaweeds. Algae can be single-celled, filamentous or plant-like, anchored to the bottom. Algae are aquatic, plant-like organisms – phytoplankton. Phytoplankton provides the basis for the whole marine food chain. Phytoplankton need light to photosynthesize so will therefore float near the top of the water, where sunlight reaches it. Light is the most limiting factor for algal growth, followed by nitrogen and phosphorus limitations), but other nutrients are required including carbon, silica, and other micronutrients. These microscopic organisms are common in coastal areas. They proliferate through cell division.
A natural progression occurs in many water bodies, from diatoms, to green algae to yellow/brown to blue-green, with time and temperature. The environment is important. Southern waters are characterized as being slow moving, and warm. This encourages cyanobacteria – or blue green algae. The introduction of nutrients is particularly difficult as it accelerates the formation of the blue green algae. Blue-green algae creates the bright green color, but is actually an end-of-progression organism.
If cells are present in the water mass in large numbers an algal bloom occurs. An algal bloom is simply a rapid increase in the population of algae in an aquatic system. Blooms may occur in freshwater as well as marine environments. Colors observed are green, bright green, brown, yellowish-brown, or red, although typically only one or a few phytoplankton species are involved and some blooms may be recognized by discoloration of the water resulting from the high density of pigmented cells.
So the desire for development created the idea to drain the swamp, which led to exposure of dark, productive soil that led to farming, which lead to fertilizers, which led to too much water, and water pollution leading to algae. A nice, predictable progression created by people. So what is the solution?