Non flowing (lentic) water bodies like lakes and reservoirs are not permanent features of the lands cape. The young lakes and reservoirs are relatively barren bodies of water and are deficient in nutrients which are necessary to support aquatic life. At this stage they bare referred to a being oligotrophic with the passage of time the materials retained by the lake gradually increase in the bottom sediments and the water bodies become highly productive or eatrophic. Through bacterial and other decompositions of the sediments, the water becomes rich in nutrients on which phytoplanktons thrive with the increase in phytoplankton’s and food supply, the zoo plankton and other animal forms also increase. Now the water bodies pass from olgotrophic phase to the mesotrophic and finally into the entrophic phase.
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However due to human activities like dumping domestic waste, agriculture and land drainage organic wastes from industries, there is rapid eutrophication. The nutrient rich waste induce productively and composition of aquatic life.
Control of Eutrophication:
- Limited input of nutrients through treatment of waste water before being discharged to water bodies.
- Reduction in the amount of nutrients dissolved in water through stimulation of bacteria multiplication.
- Harvesting and removal of algal blooms to check the recycling of nutrient into the water upon death and decomposition.
- Removal of dissolved nutrients from water through physical chemical and biological methods like precipitation, biological , nitrification and denitrification, ion exchange, electrolysis and reverse osmosis.