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?
A week or so ago, on a Sunday afternoon, I flew across Middle America to Colorado for a meeting and was again struck by the crop circles that dominate the landscape west of the Mississippi River. They are everywhere and are a clear sign of unsustainable groundwater use. I recently participated in a fly in event for National Groundwater Association in Washington DC, where several speakers, including myself, talked about dwindling groundwater levels and the impact of agriculture, power and economies. The impact is significant. Dr. Leonard Konikow, a recently retired USGS scientist, noted that he thinks a portion of sea level rise is caused by groundwater running off agriculture and from utilities and making its way to the ocean. He indicated that 5% of SLR each year was caused by groundwater runoff, and has upped his estimates in the past 10 years to 13%. This is because it is far easier for water to runoff the land than seep into rocks, especially deep formations that may take many years to reach the aquifer. And since ET can reach 4 ft below the surface, many of the western, dry, hot areas lose most of this water during the summer months. Hence the impact to agriculture, and the accompanying local communities and their economies will be significant.
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