THE EFFECTS OF THERMAL POLLUTION ON MARINE LIFE

By Surabhi Tanwar

1) DECREASE IN DO (Dissolved Oxygen) LEVELS:

• Cold water contains more oxygen than hot water so increases in temperature also decrease the oxygen-carrying capacity of water.

• In addition, raising the water temperature increases the decomposition rate of organic matter in water, which also depletes dissolved oxygen.

• These decreases in the oxygen content of the water occur at the same time that the metabolic rates of the aquatic organisms, which are dependent on a sufficient oxygen supply, are rising because of the increasing temperature.

• Ocean invertebrates, fish and marine reptiles are obligate poikilotherms -- their body temperatures depend entirely on the surrounding water.

• Each species is adapted to a single range of temperatures and many pass through several different life stages, each with an individual range of tolerance. The ocean's vast populations of microbes, fungi and sea plants also rely on narrow temperature ranges for optimal growth.

• Thermal pollution often temporarily increases aquatic plant populations. Other life forms, including microbes and animals, move into these regions to exploit the higher oxygen levels, but when photosynthesis stops at night or upon the death of plants, dissolved oxygen levels plummet, leading to massive animal die-offs. Excess heat can also cause unnaturally large microbial blooms, which kill animals by depleting local oxygen or producing toxins.

• Unnatural warmth and cold can also delay and redirect migration, influence when and whether breeding occurs, and decrease survival of young in marine mammal, reptile and bird populations.

• Heat pollution that leads to an overabundance of organisms in a region can draw in excessive numbers of creatures that feed on them, while depletion of prey populations by heat stress forces their predators to encroach on regions outside their normal range. Both situations lead to unnatural competition between and within species.

2) MIGRATION :

• A sudden thermal shock can result in mass killings of fish, insects, plants or amphibians.

• Hotter water may prove favorable for some species while it could be lethal for other species. Small water temperature increases the level of activity while higher temperature decreases the level of activity.

• Many aquatic species are sensitive to small temperature changes such as one degree Celsius that can cause significant changes in organism metabolism and other adverse cellular biology effects.

3) ECOLOGICAL IMPACT :

• A significant halt in the reproduction of marine wildlife (although this may be true, reproduction can still occur between fish – but the likelihood of defects in newborns is significantly higher) can happen due to increasing temperatures as reproduction can happen with in certain range of temperature.

• Excessive temperature can cause the release of immature eggs or can prevent normal development of certain eggs.

4) AFFECT ON REPRODUCTIVE SYSTEM :

• Outside of ideal temperatures, digestive enzymes begin to fail, altering organisms' rate of growth and ultimate size.

• Altered temperature can cause the need for more food and farther travel farther to find it, placing stress on surrounding populations as hungry interlopers encroach.

• Excess heat can confuse animals' ability to determine season and even direction.

→ It is also important to know that, thermal pollution can also trigger malnutrition in the affected organisms. Increase in the water temperature interferes with enzymes which are responsible for breaking down of lipids.

5) DIGESTIVE SYSTEM :

• A nuclear power-generating station on Nanwan Bay in Taiwan caused bleaching of corals in the vicinity of the discharge channel when the plant first began operation in 1988.

• Studies of the coral Acropora grandis in 1988 showed that the coral was bleached within two days of exposure to temperatures of 91.4°F.

• In 1990 samples of coral taken from the same area did not start bleaching until six days after exposure to the same temperature. It appears that the thermotolerance of these corals was enhanced by the production of heat-shock proteins that help to protect many organisms from potentially damaging changes in temperature.

Marine

http://animals.pawnation.com/effects-thermal-pollution-marine-life-7712.html

http://everydaylife.globalpost.com/effects-thermal-pollution-marine-life-40307.html

http://www.conserve-energy-future.com/causes-and-effects-of-thermal-pollution.php

http://www.slideshare.net/amba_slide/marine-pollution-8524112

http://www.slideshare.net/nileshjakher/thermal-pollution-16258502

http://www.powershow.com/view/1ac5e3-ODYxY/Thermal_Pollution_powerpoint_ppt_presentation

Presentation by: Surabhi Tanwar

Student of Masters in Environmental Science- Institute of Science, Mumbai