Explain five effects of water pollution.

Explanation

Effects of water pollution :
Release of sewage decreases dissolved oxygen ( used by microbes for degradation of organic matter ) and causes mortality of fish and other aquatic organisms.
Sewage contains many pathogenic microorganisms that spread serious diseases like dysentery, typhoid, jaundice, cholera, etc.
Presence of large amounts of nutrients in water causes excessive growth of planktonic algae, i.e., algal bloom that change the colour of water and deterioration of water quality and results in fish mortality.
Release of nutrients such as nitrogen and phosphorus causes eutrophication which leads to the excessive growth of aquatic weeds like water hyacinth. ( Eichhornia crassipes- Terror of Bengal).
`cdot` Toxic substances such as mercury, cadmium, copper, lead, etc. undergo biologocal magnifiaction ( biomagnification) in the aquatic food chain and cause harmful effects on animals of different trophic levels.
`cdot` thermal waste water reduces the number of organisms sensitive to high temperature, and may enhance the growth of plants and fish in extremely cold areas but, only after causing damage to the indigenous flora and fauna.