Water which is the basic substance for life is also the home of many species. A significant percentage of human beings depend on sea-food. But today the marine diversity is endangered by harmful human activities. Attention to this issue was paid in several United Nations conferences which started from the 1950’s. Earlier there was a perception among the scientists that the capacity of the sea is enormous and it can dilute any number of quantities, which are thrown in it. But gradually this perception was broken when large number of species went extinct. Many species of manatees, dolphins, turtles, sea-lions, coral reefs, etc are endangered. The total number of aquatic species which are threatened to become extinct in the coming year is 2251 (320 marine and 1931 inland water species). Different species of frogs and toads are also vulnerable to the contamination of the pollution of the sea; many types of diseases and infirmities have developed in frogs in recent years.
Some of the reasons for extinction of different marine species are:
The Dumping of toxic wastes in Sea- Different types of waste are thrown in the sea without any type of recycling process. It is estimated that 80% of the total sea pollution comes from the land based activities. Many factories throw their effluent in the rivers, and through rivers that waste ultimately reaches the sea. Sea beaches, which are a place of tourist attraction, are a major source of pollution.
Oil Pollution- Many a times black tar like oil is washed onto beaches, killing sea birds and other aquatic animals. This tar like oil comes from the tankers which washout their holds while out at sea to save time at the port. The responsibility of obeying the concerned laws in this regard rests mainly on the captain. Once the oil is poured and the tanker is sailed, it is an impossible task to determine which tanker poured the oil. In 1992, 4 million tones of oil were poured into the sea. In a research by the US National Science Foundation, it was found that only 2% of the total hydrocarbon pollution is created by tanker accidents; 11% comes from natural resources, tar sands and oil seeps, 13 % comes from the atmosphere, 24% from all forms of transport and 50% comes from drains from cities and industries. The waste of oil, i.e., tar should not be thrown directly into the sea but should be recycled before throwing into the sea.
Illegal Hunting- Marine animals like the box turtles are hunted for their meat and for use in traditional Chinese medicine. According to World Chelonian Trust more than 700,000 turtles were shipped from the USA to China between 2003 to 2005. There are some species of fishes which are endangered, yet they are being caught, world over for medicinal purposes.
Bottom Trawling- This is a method of fishing in which the sea-bed is disturbed, creating a cloud of muddy water in order to hide a net which is drawn near the bottom of the sea bed. The net is such that it is closed at the end away from the fish, has a device which enables it to move forward and a source of noise is located at that point. A deliberate noise is created to attract the fish which begin to swim towards it. As this net keeps moving forwards, the fish finally get tired and fall into the closed end of the net. Bottom Trawling kills a large number of corals, sponges and fish.
Global Warming- Because of global warming the temperature of the sea water is increasing. Marine species such as the Ice fish, sea pigs, giant sea spiders, octopus, rare rays and basket stars etc are aquatic species which are accustomed to live in the cold water are finding it impossible to adapt to the rising water temperatures.