Question

How does water pollution affect biodiversity?

Answer 1

• The discharge of toxic synthetic chemicals and heavy metals into the environment has a huge impact on species abundance, and can lead to extinctions. Substances that are “natural” can become pollution when they are too abundant in a certain area. For example, nitrogen and phosphorous are important nutrients for plant growth, but when they concentrate in water systems after being applied as agricultural fertilizers, they can cause “dead zones” that are uninhabitable for fish and other wildlife.Also, carbon dioxide is a “natural” component of the atmosphere, but is considered a pollutant when emitted by human industrial activities.

• Bioaccumulation is an important concept connected with pollution. This is the process of chemicals becoming increasingly concentrated in animal tissues as they move up the food chain and can be a serious problem for biodiversity, and especially for marine mammals. Many agricultural and industrial chemicals are persistent organic pollutants (POPs), which do not seem to cause biological damage at very low concentrations. However, these POPs are easily incorporated into organisms like bacteria, phytoplankton, and other invertebrates at the bottom of marine food chains. As those organisms are eaten by fish, and fish are eaten by marine mammals, the POPs move up the food chain and affect the whole biodiversity.

• Eutrophication:Introduction of substances like fertilizers, organic waste, sewage or decaying matter results in the increase of chemicals nutrients like nitrogen and phosphorus. This causes water pollution. The presence of these nutrients in higher levels promotes excessive algal blooms in water. These algae use up oxygen during the night. The excessive growth of algae also blocks sunlight which hinders the process of photosynthesis of plants under water. The decaying process of these algae also requires oxygen which also decreases the oxygen content in water.

• Polluted water caused by oil and petroleum chemicals poison organisms and humans that take them up. Oil when introduced into the water body remains on the surface of the water and blocks sunlight penetrating into the water and affects the organisms in water. Oil that gets on the body of animal’s paralyses them making it difficult for them to escape from predator’s or drowns them.

• Thermal pollution is the degradation of water quality by any process that changes ambient water temperature.A common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers. When water used as a coolant is returned to the natural environment at a higher temperature, the change in temperature (a) decreases oxygen supply, and (b) affects ecosystem composition. Urban runoff--stormwater discharged to surface waters from roads and parking lots--can also be a source of elevated water temperatures.