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Mercury Poisoning – Minamata Disease

Mercury Poisoning in Fishes

Mercury is a naturally occurring chemical, but it can become harmful when it contaminates fresh and seawater areas. Fish and other aquatic animals ingest the mercury, and it is then passed along the food chain until it reaches humans.

Mercury in humans may cause a wide range of conditions including neurological and chromosomal problems and birth defects.

Minamata Disease

Minamata disease, sometimes referred to as Chisso-Minamata disease, is a neurologicalsyndrome caused by severe mercury poisoning. Symptoms include ataxia, numbness in the hands and feet, general muscle weakness, narrowing of the field of vision and damage to hearing and speech. In extreme cases, insanity, paralysis, coma and death follow within weeks of the onset of symptoms. A congenital form of the disease can also affect fetuses.

Oil Spills

In Oil Spills, the oil is released into the ocean or coastal waters. The Oil may be crude oil from the tankers, offshore platforms, drilling rigs, Oil wells, ships or in any other form.

Impact on Marine Life

Oil destroys the insulating ability of fur-bearing mammals, such as sea otters, and the water repellency of a bird’s feathers, thus exposing these creatures to the harsh elements. Without the ability to repel water and insulate from the cold water, birds and mammals will die from hypothermia. Many birds and animals also ingest oil when they try to clean themselves, which can poison them.

Fish and shellfish may not be exposed immediately, but can come into contact with oil if it is mixed into the water column. When exposed to oil, adult fish may experience reduced growth, enlarged livers, changes in heart and respiration rates, fin erosion, and reproduction impairment. Oil also adversely affects eggs and larval survival.


Containing floating oil within booms for recovery by specialised skimmers is often seen as the ideal solution to a spill at sea as this aims to physically remove oil from the marine environment. As a result, it is the primary at-sea response strategy adopted by many governments around the world.

For containment and recovery of oil to be successful, there are some key challenges that must be overcome. The drifting floating oil must be located and the equipment deployed in an effective arrangement. The sea state and weather conditions must be sufficiently calm to permit the selected equipment to function well and for the response personnel to safely operate the equipment.

The oil must also be in a state that is amenable for recovering using the available skimmers. These interrelated challenges commonly combine to limit the proportion of spilled oil that can be recovered to 10-15%. However, where the environment conditions and response factors allow, containment and recovery can be an important strategy.

Largest Oil Spills

  1. Gulf War, 1991


240 to 336 million gallons

  1. Deepwater Horizon 2010

Mexican Gulf

210 million gallons

  1. Ixtoc 1 Oil Well, 1979

Bay of Campeche, Mexico

140 million gallons

  1. Atlantic Empress, 1979

Trinidad and Tobago, West Indies

88.3 million gallons

  1. Fergana Valley, 1992


87.7 million gallons

  1. ABT Summer, 1991

Off the coast of Angola

80 million gallons

Bioremediation of Oil Spills

Specific bacteria can be used to bioremediate specific contaminants, such as hydrocarbons, which are present in oil and gasoline. Oceanic oil spills are managed using containment methods (floats on the water) and bioremediation (adding bacteria to the oilto speed up the breakdown process).

Oil Zapper

In 2010, a new technique of using the bacteria to get rid of oil spill became popular called Oil Zapper. Oil Zapping is a bio-remediation technique involving the use of ‘oil zapping’ bacteria.

United Nations Convention on the Law of the Sea (UNCLOS)

The United Nations Convention on the Law of the Sea (UNCLOS), also called the Law of the Sea Convention or the Law of the Sea treaty, is the international agreement that resulted from the third United Nations Conference on the Law of the Sea (UNCLOS III), which took place between 1973 and 1982. The Law of the Sea Convention defines the rights and responsibilities of nations with respect to their use of the world’s oceans, establishing guidelines for businesses, the environment, and the management of marine natural resources. The Convention, concluded in 1982, replaced four 1958 treaties. UNCLOS came into force in 1994, a year after Guyana became the 60th nation to ratify the treaty. As of June 2016, 167 countries and the European Union have joined in the Convention. It is uncertain as to what extent the Convention codifies customary international law.

While the Secretary General of the United Nations receives instruments of ratification and accession and the UN provides support for meetings of states party to the Convention, the UN has no direct operational role in the implementation of the Convention. There is, however, a role played by organizations such as the International Maritime Organization, the International Whaling Commission, and the International Seabed Authority (ISA).

  1. Internal waters

Covers all water and waterways on the landward side of the baseline. The coastal state is free to set laws, regulate use, and use any resource. Foreign vessels have no right of passage within internal waters.

  1. Territorial waters

Out to 12 nautical miles (22 kilometres; 14 miles) from the baseline, the coastal state is free to set laws, regulate use, and use any resource. Vessels were given the right of innocent passage through any territorial waters, with strategic straits allowing the passage of military craft as transit passage, in that naval vessels are allowed to maintain postures that would be illegal in territorial waters.

“Innocent passage” is defined by the convention as passing through waters in an expeditious and continuous manner, which is not “prejudicial to the peace, good order or the security” of the coastal state. Fishing, polluting, weapons practice, and spying are not “innocent”, and submarines and other underwater vehicles are required to navigate on the surface and to show their flag. Nations can also temporarily suspend innocent passage in specific areas of their territorial seas, if doing so is essential for the protection of its security.

  1. Archipelagic waters

The convention set the definition of Archipelagic States in Part IV, which also defines how the state can draw its territorial borders. A baseline is drawn between the outermost points of the outermost islands, subject to these points being sufficiently close to one another. All waters inside this baseline are designated Archipelagic Waters. The state has sovereignty over these waters (like internal waters), but subject to existing rights including traditional fishing rights of immediately adjacent states. Foreign vessels have right of innocent passage through archipelagic waters (like territorial waters).

  1. Contiguous zone

Beyond the 12-nautical-mile (22 km) limit, there is a further 12 nautical miles (22 km) from the territorial sea baseline limit, the contiguous zone, in which a state can continue to enforce laws in four specific areas: customs, taxation, immigration and pollution, if the infringement started within the state’s territory or territorial waters, or if this infringement is about to occur within the state’s territory or territorial waters. This makes the contiguous zone a hot pursuit area.

  1. Exclusive economic zones (EEZs)

These extend 200 nautical miles (370 kilometres; 230 miles) from the baseline. Within this area, the coastal nation has sole exploitation rights over all natural resources. In casual use, the term may include the territorial sea and even the continental shelf.

The EEZs were introduced to halt the increasingly heated clashes over fishing rights, although oil was also becoming important. The success of an offshore oil platform in the Gulf of Mexico in 1947 was soon repeated elsewhere in the world, and by 1970 it was technically feasible to operate in waters 4,000 metres deep. Foreign nations have the freedom of navigation and overflight, subject to the regulation of the coastal states. Foreign states may also lay submarine pipes and cables.

  1. Continental shelf

The continental shelf is defined as the natural prolongation of the land territory to the continental margin’s outer edge, or 200 nautical miles (370 km) from the coastal state’s baseline, whichever is greater.

A state’s continental shelf may exceed 200 nautical miles (370 km) until the natural prolongation ends. However, it may never exceed 350 nautical miles (650 kilometres; 400 miles) from the baseline; or it may never exceed 100 nautical miles (190 kilometres; 120 miles) beyond the 2,500-meter isobath (the line connecting the depth of 2,500 meters).

Coastal states have the right to harvest mineral and non-living material in the subsoil of its continental shelf, to the exclusion of others. Coastal states also have exclusive control over living resources “attached” to the continental shelf, but not to creatures living in the water column beyond the exclusive economic zone.

UNCLOS and problem of Arctic

There is an absence of modern regulatory tools, such as the precautionary approach, and a lack of necessary tailor-made measures to protect the extremely fragile environment and ecosystems of the Arctic.  No requirement of integrated, cross-sectoral ecosystem-based ocean management.

The Arctic Ocean requires a regional agreement tailor-made for arctic conditions developed under the overarching framework of UNCLOS similar to the Regional Seas Agreements. The goal is not to dismiss the UNCLOS rules but to make them work in the Arctic at the regional level effectively through regional rules of protection. The Arctic marine environment will be better protected if there is a Regional Seas Agreement signed.

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