What is Eutrophication?
Eutrophication is a process whereby water bodies, such as lakes, estuaries, reservoirs or slow-moving streams receive excess nutrients that stimulate excessive growth of aquatic plant and algae. Eutrophication is caused by an increase in nutrient levels; usually phosphorus and nitrogen and can result in visible cyanobacterial or algal blooms, surface scums, floating plant mats and benthic macrophyte aggregations. Concentrations of phosphorus of < 0.1 mg/L are sufficient to cause a cyanobacterial (algal) bloom. The decay of this organic matter may lead to oxygen depletion in the water, which in turn can cause secondary problems such as fish kills and liberation of toxic substances or phosphates that were previously bound to oxidized sediment.
Eutrophication is a process by which plant growth increases in a lake or pond. In time, eutrophication may cause plants to completely fill in the area where a lake or pond once stood. The word “eutrophic” is of Greek origin, meaning “truly nourished.” The accelerated growth and overcrowding of plants is due to either natural fertilizing agents that are washed from the soil, or the runoff of chemical fertilizers applied to agricultural lands. Eutrophication may also be brought about by the drainage of sewage, industrial wastes, or detergents into a body of water. As the overcrowded plants die off, the dead and decaying vegetation depletes the lake’s oxygen supply. This, in turn, leads to the death of fish in the lake. The accumulated dead plant and animal material eventually changes a deep lake to a shallow one. The shallow lake then becomes a swamp, and finally it becomes dry land….
Eutrophication refers to an increase of nutrients in a body of water. Although eutrophication is a natural process, when it is accelerated it is an issue for concern. Many human activities have led to widespread eutrophication in rivers, streams, lakes, and oceans around the world. If left unchecked, eutrophication becomes a problem, severely impacting water quality and biodiversity. Eutrophication was first recognized as a problem in the middle of the 20th century, and many biologists study it extensively in an attempt to prevent further eutrophication of vital bodies of water around the world. In the sense of a natural process, eutrophication is part of the aging of bodies of water. When a body of water initially forms, it tends to be low in nutrients. As streams feed the body of water, they carry nutrients which foster plant life, ultimately allowing other species to grow as well.
There are three main stages that make up the essential cycle of eutrophication: oligitrophy, mesotrophy, and eutrophy (Pringal). These stages represent the lake from its beginning to its death, specifying how old the lake is. When one or more of these stages is sped up or even skipped over completely, the natural balance is disrupted and can result in the annihilation of the body of water. Oligitrophy is the beginning stage of a lake. The lake is rich in dissolved oxygen, but lacks essential plant nutrients such as nitrogen and phosphorus. This means that the lake also has a lack of fertility that limits animal life in the lake. In its mid-life, the lake becomes mesotrophic. The nutrients, such as decaying organic matter or man made items such commercial fertilizers, flowing into the lake accumulate in the bottom sediments along with nutrients that settled from decay of the lake’s own organisms.
Eutrophication is also known as nutrient pollution. Eutrophication is the process where nutrients, mainly nitrogen and phosphorus, are added to bodies of water and can act like fertilizer causing the growth of algae. Excessive amounts of nutrients can lead to more serious problems such as low levels of oxygen dissolved in the water. This can kill fish, crabs, oysters, and other aquatic animals. To help us dive a little deeper into this question, we will talk with Dr. Suzanne Bricker about eutrophication – what it is, what it means, and what scientists are doing about it. Suzanne is a Physical Scientist from the National Centers for Coastal Ocean Science. Hi, Suzanne, welcome to our show. SUZANNE BRICKER: Hi Kate, thanks for having me today. I’m looking forward to talking about eutrophication and some of the studies that we’ve done to understand nutrient pollution in our nation’s estuaries. (DEFINING EUTROPHICATION) HOST: Thanks Suzanne.
