Environmental Studies(ES)

ENVIRONMENTAL STUDIES

Lesson 19: Marine pollution

Effects of marine pollution

• Apart from causing Eutrophication, a large amount of organic wastes can also result in the development of ‘red tides’. These are phytoplankton blooms because of which the whole area is discolored.
• Commercially important marine species are also killed due to clogging of gills and other structures.
• When oil is spilled on the sea, it spreads over the surface of the water to form a thin film called as oil slick. This damages marine life to a large extent. Commercial damage to fish by tainting which gives unpleasant flavor to fish and sea food reduces market values of sea food and causes death of birds through its effect on feathers. Birds often clean their plumage by pruning and in the process consume oil which can lead to intestinal, renal and liver failure.
• For salt marshy plants oil slick can affect the flowering, fruiting and germination.

• Organic waste addition results in end products such as hydrogen sulphide, ammonia and methane which are toxic to many organisms. This process results in the formation of an anoxic zone which is low in its oxygen content; from which most life disappears except for anaerobic microorganisms and renders the water foul smelling.
• The coral reefs are the productive ecosystems offer many benefits to people. These coral reefs are threatened by a) the sediments from deforestation carried by the runoffs. b) the agricultural and industrial chemicals reaching through river discharges.To mention an example, River Ganga is estimated to carry 1.5 billion tons of sediments due to deforestation and intensive farming in India, Bangladesh and Nepal through which it flows to Bay of Bengal.
• Drill cuttings dumped on the seabed result in the production of toxic sulphides in the bottom sediment thus eliminating the benthic fauna.