Eutrophication is characterized by excessive growth of plants and algae due to the increased availability of one or more growth limiting factors necessary for photosynthesis, such as sunlight, carbon dioxide, and nutrient fertilizers. Eutrophication occurs naturally over centuries as lakes age and fill with sediment. However, human activities have accelerated the rate and extent of eutrophication through point discharges and non-point loads of limiting nutrients, such as nitrogen and phosphorus, in aquatic ecosystems (cultural eutrophication), with dramatic consequences for sources of water. drinking water, fisheries and recreational water bodies.
For example, aquaculture scientists and pond managers often intentionally eutrophy water bodies by adding fertilizers to increase primary productivity and increase the density and biomass of economically important recreational fish through upward effects on fish. higher trophic levels. However, during the 1960s and 1970s, scientists linked algal blooms to nutrient enrichment resulting from anthropogenic activities such as agriculture, industry, and wastewater disposal. Known consequences of cultural eutrophication include blue-green algal blooms, contaminated drinking water supplies, degradation of recreational opportunities, and hypoxia. TheEstimated cost of damage mediated by eutrophication in the United States is approximately $ 2.2 billion annually.
The most notable effect of cultural eutrophication is the creation of dense blooms of noxious and smelly phytoplankton that reduce water clarity and damage water quality. Algal blooms limit light penetration, reducing growth and causing the death of plants in coastal areas, while also reducing the success of predators that need light to chase and catch prey. Additionally, the high rates of photosynthesis associated with eutrophication can deplete dissolved inorganic carbon and raise pH to extreme levels during the day.
Elevated pH can in turn be a “blind” organism that depends on the perception of dissolved chemical signals for its survival by affecting its chemosensitive abilities.
