Seawater / River Water

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Zooplankton and its influence in water quality

What are Zooplankton?


Zooplankton are microscopic animals that live in both fresh and marine waters. They drift in the water, floating freely or remain passively suspended in the water. The zooplankton feed on the planktonic algae and there is a dynamic relationship between the zooplankton and the phytoplankton populations in a given body of water.

The zooplankton community in fresh water is principally compromised of free-living protozoans, rotifers, cladoceraus and copepods. The species diversity & numbers help in ascertaining water quality.


Zooplankton's influence on water quality


Due to the short life cycle, zooplankton respond quickly to environmental changes and could therefore be an additional tool to monitor and track the changes in the quality of the water environment.

When zooplankton numbers rise to high levels, there is the potential to impact and influence water quality through taste and odour. The rise and fall of zooplankton populations leads to decomposition of their dead bodies which is manifested in unpleasant odours and accumulation of organic debris lowering water quality, increasing turbidity and colour, depleting dissolved oxygen and raising organic carbon levels. Further, increased zooplankton numbers are known to pose a nuisance by blocking filters and interfering with water treatment and disinfection procedures, thereby reducing the efficiency of plants.