In the mid-20th century,due to lack of information on eutrophication, this phenomenon in Europe andNorthern America was thought to be water pollution. Ever since then, it wasrealised that this phenomenon is being distributed widely, not only in Europeand Northern America, but across the world. According to statistics, 54% oflakes in Asia are eutrophic, 53% in Europe and 28% in Africa. However, a studyby the CSIR has shown that in South Africa, more than 60% of the dams surveyedwere eutrophic.
Many effects can arise due to the occurrenceof eutrophication. When this phenomenon becomes intense, undesirable effectswill follow which will not only affect the water source but also theenvironment. Firstly, eutrophication will change the aquatic ecosystem. This issaid so because there will be formation of a detritus layer. Detritus layer islayer of organic materials suspended on the seabed, piling up as more and moreorganic materials suffocate and die due to lack of oxygen. Besides that,eutrophication also changes the aquatic ecosystem into a marshy land as when deadplants and organisms die, they sediment at the seabed, causing water to be moreturbid. This indirectly will also prevent touristic use of the lake as thecolour and smell of the lake will be unappealing. Plus, such a water source cancause skin irritation and can also promote certain other illness, depending onthe sensitivity of a person.
Secondly, eutrophication alsodecreases biodiversity in the ecosystem. This is said so because eutrophicationis the condition where the water surface is covered by algae and this preventssunlight from penetrating into the water body. As a result, plants begin to diedue to lack of oxygen. Once the producers die, the consumers will also begin todie as the oxygen concentration in the water source further decreases. Thiswill also lead to a significant decrease in the fishery affairs and decreasethe quality of aquatic organisms.
Unknowingly, some aquatic organisms can alsobe poisonous if consumed. Not only that, if any other organisms consume waterfrom that particular water source, it may face a high risk of damage to theinternal body system.Apartfrom that, eutrophication can also cause new species invasion. This is due to thechange in the condition of the water source from aerobic condition to anaerobiccondition.
Aerobic condition is the condition where there is sufficient supplyof oxygen while anaerobic condition is the condition where there is eitherlimited or no oxygen at all. Therefore, a new class of species, which can adaptto this environment will emerge. For example, plasmodium sp.
will then emergewhich will out-compete the original inhabitant species. This has been proven inNew England Salt Marshes.Otherthan that, eutrophication increases the toxicity of the water body.
Forinstance, anaerobic bacteria and algae can produce neurotoxins andhepatotoxins, which are lethal to aquatic organisms, human beings and mammals. Thetoxins they produce can make their way up the food chain and result in animalmortality. An example of this is shellfish poisoning. Toxins released duringblooming of algae is taken up by shellfish such as oysters and mussels. Thiswill cause food to acquire toxins and hence, cause food poisoning in humans.
Therefore,eutrophication also disturbs the entire ecosystem