Plastic pollution is a big threat to marine biodiversity

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Plastic pollution is a big threat to marine biodiversity

THE SouthernTIMES Mar 19, 2018

    > Dr Moses Amweelo

    The increasing use of synthetic materials to replace glass or tin for containers and natural fibres for ropes and nets has introduced a new type of marine pollution.

    These materials are not readily degradable and they persist in the environment.

    Being buoyant, they float in the sea. Persistent plastics accumulate in shallow water and strand on beaches. Plastic pollution can unfavourably affect lands, waterways and oceans.

    Living organisms, particularly marine mammals, fish, and birds, while discarded fishing nets continue to trap marine organisms for long time, can also be affected through entanglement, direct ingestion of plastic waste, or through exposure to chemicals within plastics that cause interruptions in biological functions.

    Humans are also affected by plastic pollution, such as through the disruption of the thyroid hormone axis or hormone levels.

    There are three major forms of plastic that contribute to plastic pollution: micro plastics as well as mega and macro plastic.

    Mega and micro plastics have accumulated in highest densities in the Northern Hemisphere, concentrated around urban centres and water fronts.  

    In 2012, it was estimated that there was approximately 165 million tons of plastic pollution in the world’s oceans.

    One study estimated that there are more than five trillion plastic pieces (defined into the four classes of small micro plastics, large micro plastics, meso-and macro plastics) afloat at sea.  

    Dr Stefan Micallef Director, Marine Environment Division, IMO said: There will be more plastics in the ocean than fish by 2050 if we continue with our habits. 

    The litter that is being delivered into the oceans is toxic to marine biodiversity and humans.

    The toxins that are components of plastic include diethylhexyl phthalate, which is a toxic carcinogen, as well as lead, cadmium, and mercury.

    Plankton, fish, and ultimately the human race, through the food chain ingest these highly toxic carcinogens and chemicals.

    Consuming the fish that contain these toxins can cause an increase in cancer, immune disorders and birth defects.

    While some of these problems are alleviated by good housekeeping, they are best tackled at source. Extensive regulations already exist at the local level, and legislation to prevent disposal of plastics is now being introduced in several countries as well as internationally.

    The quality of the coastline and the safety of marine biodiversity could be much improved by greater public awareness and involvement, and by more rigorous enforcement of existing rules.

    The International Maritime Organizatio (IMO) for its part has pioneered the prohibition of plastics’ disposal anywhere at sea, which took effect more than 25 years ago when Annex V of the MARPOL Convention entered into force in 1988.

    Plastic materials in all shapes and sizes are omnipresent in our seas and oceans and are the worst form of marine litter because they are non-biodegradable. In 1982, the United Nations Convention on the Law of the Sea was adopted.

    Its provisions on the protection and preservation of the marine environment established an overall framework of governing principles and general obligations notably those requiring States to take all necessary measures to prevent, reduce and control marine pollution from any source, and to co-operate, on global and regional bases, as appropriate, in the formulation and elaboration of international rules, standards and recommended practices and procedures and in the establishment of appropriate scientific criteria for these purposes.

    The obligation to co-operate also extends to the notification of imminent or actual damage, the adoption of contingency plans against pollution, and the carrying out of research programmes.

    Development of technology for degradable synthetic materials to replace current plastic products, as appropriate.

    In this connection, Governments should also study the impacts on the environment of the products of degradation of such new materials.

    In addition to the environmental and health problems posed by marine debris, floating garbage and plastics pose a costly as well as dangerous problem for shipping as they can be a navigational hazard and become entangled in propellers and rudders.

    • Dr Moses Amweelo is Namibia’s former minister of works, transport and communication as well as a marine safety expert.

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