Eutrophication is a process characterized by excessive plant and algal growth due to the increased availability of one or more limiting growth factors needed for photosynthesis, such as sunlight, carbon dioxide, and nutrient fertilizers. Eutrophication occurs naturally over centuries as lakes age and are filled in with sediments, but human activities have accelerated the rate and extent of eutrophication through both point-source discharges and non-point loadings of limiting nutrients, such as nitrogen and phosphorus, into aquatic ecosystems. This is known as cultural eutrophication and has dramatic consequences for drinking water sources, fisheries, and recreational water bodies.
The primary cause of eutrophication is an overabundance of nutrients, primarily nitrogen and phosphorus, in water. These nutrients occur naturally, but most of the nutrients in our waterways come from human activities and sources such as fertilizers, wastewater, automobile exhaust, and animal waste. When these nutrients enter a body of water, they start a process called eutrophication. Algae feed on the nutrients, growing and spreading rapidly, leading to an overabundance of algae and plants.
Eutrophication sets off a chain reaction in the ecosystem, starting with an overabundance of algae and plants. The excess algae and plant matter eventually decompose, producing large amounts of carbon dioxide. This lowers the pH of seawater, a process known as ocean acidification. Acidification slows the growth of fish and shellfish and can prevent shell formation in bivalve mollusks. Eutrophication has had significant economic impacts on commercial shellfisheries, and recreational opportunities have been degraded.
In summary, eutrophication is caused by an overabundance of nutrients, primarily nitrogen and phosphorus, in water, which leads to excessive plant and algal growth. This process is accelerated by human activities and sources such as fertilizers, wastewater, and animal waste. The consequences of eutrophication include blooms of noxious, foul-smelling phytoplankton that reduce water clarity, harm water quality, and have significant economic impacts on commercial shellfisheries.
