Eutrophication - A Threat to the Aquatic Environment


The process of eutrophication is driven by the enrichment of water with nutrients, particularly those high in nitrogen and/or phosphorus, which causes an increase in the growth, primary production, and biomass of algae as well as changes in the organismal balance and degradation of water quality. Eutrophication's effects are unfavorable if they significantly reduce ecosystem health, biodiversity, and/or the sustainable production of products and services.

The main inorganic nutrients that cause the eutrophication of marine waters are nitrogen and phosphorous. Marine waters naturally include nitrogen and phosphorus, which are transported there from the land by streams, rivers, and runoff from rainfall as well as by the breakdown of organic matter already present in the water. The amount of nitrogen and phosphorus in the oceans has increased due to human nutrient inputs into the environment.

The Main Sources of Eutrophication

On land, particularly in agricultural areas, diffuse sources account for the majority of the nitrogen load. Aquaculture, wastewater treatment facilities, industrial water, nearby oceans, and nitrogen emissions (such as ammonium from manure and nitrogen oxides from ships, which are transmitted via the atmosphere to oceans by precipitation) are some other sources of nitrogen.

The primary source of phosphate introduced by humans is found in domestic and industrial wastewater and sewage. Although phosphate is a component of fertilizers its run-off from land is also a significant source of phosphate.

Effects of Eutrophication on Aquatic Ecosystem

The term "eutrophication" is broad and refers to a significant problem in the nation's estuaries. The process of eutrophication, which happens when the environment becomes enriched with nutrients, increases the quantity of plant and algae production in estuaries and coastal waters, is what causes harmful algal blooms, dead zones, and fish kills. According to a study, excessive nitrogen imports have moderately to severely deteriorated 65 per cent of the contiguous U.S.'s estuaries and coastal waters. A surplus of nutrients causes algal blooms and hypoxic conditions, which can kill fish and seagrass and diminish vital fish habitats. Bivalve mollusc populations (such as those of oysters, clams, and scallops) are also common in many of these estuaries, and they naturally remove nutrients through filter-feeding.

An excess of algae and plants is the first sign of eutrophication, which then triggers a chain reaction in the ecosystem. As the surplus algae and plant stuff finally break down, it releases a lot of carbon dioxide. This results in ocean acidification, a process where seawater's pH decreases. The production of shells in bivalve molluscs can be prevented by acidification, which also retards fish and shellfish growth. This results in smaller harvests and more expensive seafood for both commercial and recreational fisheries due to the decreased harvest.

Eutrophication can cause a decrease in the quantity of sunlight that bottom waters receive, which can affect the distribution of macroalgae and seagrasses by depth. Oxygen deficit in bottom waters can be caused by an increase in the decomposition of organic materials (dead algae). Reduced oxygen levels may therefore affect fish and benthic fauna (animals that live on the bottom of lakes or oceans), causing them to leave the area or perish. Moreover, eutrophication has the potential to alter biodiversity and ecosystem balance.

It also has socio-economic impacts such as the negative impact on the fish industry, degradation of water quality with foul smell and toxins from blooms affecting the tourism industry.

In conclusion, eutrophication is recognized as a toxic and pollution problem and a threat to water quality, marine life, tourism and economic growth.

About the Author: Muhammad Tahir is a postgraduate scholar in environmental sciences and deeply passionate about environmental studies and eager to pursue opportunities to deepen his knowledge and engagement in this area to make positive changes in this world.


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