Eutrophication refers to the degradation of water quality due to over- enrichment by nutrients such as nitrogen and phosphorous, which results in excessive algae growth and decay. The consequence is a decrease in the concentration of oxygen in the water. It is the result of discharge of sewage effluents and run-off from fertilizers into the water bodies. However, it can also occur naturally by way of accumulation of nutrients. This results in excessive growth of phytoplankton in the water body which in turn disrupts the normal functioning of the ecosystem by reducing the oxygen content which is essential for the survival of marine life. It also reduces the value of the water body as a resource and can lead to health problems by interfering with water treatment.
The problem of eutrophication ahs been recognised by the world at large and surveys show that 54% of the lakes in Asia, 53% in North America, 48% in South America 41% in Africa, 28% in Australia and 50% in Europe are eutrophic.
The increase in the nutrients results in excessive growth of algae which reduces the sunlight available to the organisms living at the bottom of the water bodies and reduces oxygen levels. Algae function differently from other organisms in the sense that they release more oxygen during the day than they use, and absorb more carbon dioxide than they release. In the night, however, they act in an opposite manner and act as a dead organic matter. Thus, under such conditions, oxygen levels increase during the day but is greatly reduced at night thereby resulting in the death of fishes, shrimps and their likes.
There is a high likelihood that the increase in the nitrogen levels may result in growth of newer species who would in turn eliminate other species who will be unsuccessful in competing with such newer species, as per Darwin’s theory.
There are some algae which are toxic to plants and animals. This in turn results in a chain effect by which humans are affected, for example in the case of shellfish poisoning.
Since eutrophication poses such a major problem to both the ecosystem and the human race, it is important to counter it and develop a sustainable solution. Clean up measures have been adopted but they have not proved to be successful as was witnessed in the case of Finland, which though achieved 90% efficiency, could not reduce run-offs in some targets even after adopting preventive measures.
Development of buffer zones between the land and the water can prove to be a successful means of trapping sediments and preventing them from reaching the water bodies. Legislations regulating the discharge of waste material in the water bodies can go a long way in addressing the problem. Reduction in the use of fertilizers by adopting the Soil Nitrogen Testing, is another effective way of controlling the flow of nutrients into the water bodies. Fertilizers can also be reduced by converting to organic manures.
However, one must take care to ensure that in the process of controlling water pollution, the population of the algae is not completely wiped out, since they play a vital role in the ecosystem and are required to provide continuity to the food chain. The focus should not be on elimination but on achieving a balance between the two creations of nature in order to ensure the existence of a healthy ecosystem.