KARACHI:
Inland hydrological bodies such as lakes, ponds or shallow sea water contain minimal levels of nutrients and as such are not very supportive for large populations of aquatic organisms. The addition of nutrients including nitrogen and phosphorus to the standing water bodies, referred to as eutrophication, is characterised by excessive plant and algal growth. It is typically a gradual process and the outcome is generally a productive ecosystem.
Nevertheless, human activities have accelerated the rate and extent of eutrophication. This is mostly due to increased availability of one or more limiting growth factors needed for photosynthesis. In recent decades, there has been a debate regarding agriculture, industry, and sewage disposal on eutrophication. Due to excessive growth of algae the ecological balance is being disturbed. Degradation of water quality due to over sedimentation of inland water bodies and oxygen deficiency is indeed damaging for the environment and marine life. The conditions in Pakistan are alarming. For instance, Manchar, which is the largest freshwater lake in Pakistan, is degrading day by day due to effluents from various industrial sectors. Moreover, the enhanced nutritional levels of shallow seawater in the coastal belt of Karachi have indicated the disposal of domestic and industrial solid waste. A very careful attitude concerning reduced phosphorus and nitrogen input may save marine biodiversity and ensure safety of shrimps and other economically and recreationally important fishes as well as human lives and health.
Dr Intikhab Ulfat
Karachi
Published in The Express Tribune, April 6th, 2022.
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