life in the globe cannot be possible without oceans. Besides governing the climate, the oceans supply us varieties of fish.
As it is believed, the life starts from the oceans. Our planet where we live is known as a planet of water or blue planet, because 71 per cent of planet is covered with oceanic water. Nearly a half of the human population of the globe lives across the oceans of the world. The remote sensing satellites and the robot vehicles could help the scientists to explore more about the oceans after 1900.
Many of the pollutants produced in the landmass ultimately go to kill the oceanic creatures, which not only pollute the oceanic bodies, but also kill the marine alga and various tiny plants floating on the sea-water. The damage causes enormous loss to the ocean and especially production of oxygen.
This amounts to cutting down of evergreen forests of landmass, which provide half of oxygen requirement of the world populations. Such types of activities also reduce fish populations of the oceanic bodies. The fishing activities as well as removal of evergreen forests at the river mouths and sea edge spell doom for the entire oceanic biodiversity.
The damage to the marine resource is already known from the daily fish catch from the Bay of Bengal which has reduced enormously. Besides, some of the marine species which were very common have either been extinct or on the verge of extinction.
So, conservation strategies for protection of oceans are urgently required. Although laws are there under the Coastal Regulation Zones for protection and conservation of oceans, yet such regulations are not implemented effectively. Recently, a shark carcass recovered from a sea-side village of north Chennai revealed that consumption of plastics led to the death of the animal. About 50 kg of plastic wastes were recovered from its intestine, which made the local young volunteers to work unitedly for maintaining the cleanliness of the beach of Kovalam. So far they have collected two tonnes of plastics and thormocol, 5,000 bottles and one tonne of old plastic wired fishing nets. Similarly, the water ways like river mouths and creeks are also clogged by plastic waste products, which prevent fish breeding. Although the CRZ laws are implemented by the State Forest Department, the State Pollution Control Board and the police, the enforcement of laws is not adequate for protection of the marine flora and fauna.
larger and heavier species like sharks and whales will be finished from the ocean due to irresponsible actions of the man. The shark is a ferocious fish with a long body, two dorsal fins and rows of sharp teeth. This species is hunted for its flesh and oil from its liver. Usually, the fish is not a human eater.
The creatures of the ocean depend on three factors to survive. light is one of them. The light zone is most important of all. The zone extends up to a depth of 650 feet, where enough of sunlight is available for the growth of green plants. The food chain of the entire ocean starts from this zone. If this zone is affected or vitiated, then whole oceanic biosphere is also vitiated. There must be a fishermen association in our State like Chennai for protection and conservation of the sunlight zone, besides that of the efforts from the State authorities.
Second is the twilight zone. The dim sunlight penetrates to this zone, which is not enough for the growth of any vegetation. In the strange situation of half-light, many fish and other animals like squids generate their own light from their bodies which are technically known as bioluminescence. The black skinned fish or squid are not found on the surface of the water during day time.
Third zone is the dark zone, where sunlight cannot reach. So it is dark. There is little food available in the zone. The big jaw, long and sharp teeth provide an excellent predatory habit to the animals in the zone. The population diversity of animal or plant is very poor.
The fourth one is the abyss zone. This zone is of high pressure environment, which is colder than any other zones. The availability of food is very poor. The creatures come over the sea floor for collection of food or depend upon the drift dead bodies of any animals. The diversities of species are very poor or less than the third zone. The community feeding of certain creatures is very excellent. The species like fish, crab, shrimp and shrimp like creatures called amphipod can strip a carcass to the bone within no time.
The presence of ocean creatures depends upon the availability of light. Similarly, the oceanic temperature varies depending on depth of ocean. Again the water pressure is 1,000 times greater than that of surface level. The water pressure also decides the diversities of the plant and animal species. At the base of the food-chain, the phytoplankton is present which is consumed by zooplankton. These are the food of larger zooplanktons and small fish. The top predators here are larger fish like shark.
The ocean creatures entirely depend on plants directly or indirectly for their existence. The tiny plants like phytoplankton trap sunlight to make their own food. Subsequently, they are consumed by the animal planktons called zooplanktons. The smaller zooplanktons are also eaten by bigger or larger zooplanktons. Then those bigger zooplanktons are eaten by smaller fish and smaller fish by the larger fish like shark and whale.
In 1997 a global survey estimated that more than 90 per cent of global coral reefs had been damaged due to various activities of man, including tourism. The constant interference of man in the biological functions of coral reefs damaged the coral biodiversities. The shipping and fishing are the main causes of destruction of coral reef. Our coral sanctuary in Andaman Nicobar Islands is the best example of conservation strategies.
The oceanic pollutions not only spoil the coral reef bodies of the seas or bays, but also damage the food chains of oceanic biosphere. Similarly, global warming caused by air pollution also changes the oceanic currents in ways it cannot be calculated. Even small changes in major surface currents can seriously affect the climate changes and weather patterns in the land. If sea levels rise by 20 inches in the next hundred years, the law-lying tropical islands will be under water.
(The writer is a former senior forest officer and an environmentalist. Tel no 9937460649)