Increased Marine Pollution and Ocean Dead Zones

The marine environment, which is the planet’s largest food producer, is coming under increasing stress from mankind’s activities. Large scale agricultural and industrial runoff, increased nitrogen uptake from the widespread burning of fossil fuels, acidification from man-made carbon dioxide, all combined with the relentless rise in ocean litter, are proving to be a major environmental threat to marine biodiversity. The increase in the number of ocean dead zones over the last number of decades is a warning that over-exploitation of the world’s oceans is not sustainable.

Sources of Marine Pollution

The major sources of marine pollution are agricultural runoff from intensive farming, nitrogen uptake from burning fossil fuels, chemical pollution from coastal development, acidification from the growing levels of atmospheric carbon dioxide and the inexorable rise in ocean debris, particularly plastics.

• Modern intensive farming, especially in the developed world relies heavily on fertilizers to increase the production of crops such as wheat, maize, corn and rice. Chapter 4 of Global Environmental Outlook 4, published by the United Nations Environmental Programme (UNEP) in 2007 explains how the nutrients from fertilizer can be carried from the land to a nation’s waterways, encouraging algae bloom in rivers and estuaries and depleting these waterways of oxygen. The chapter goes on to explain how such major rivers as the Mississippi in the United States, the Amazon in South America and the Yellow River in China can transport this oxygen depleted water to the marine environment.

• Carbon dioxide is not the only environmentally damaging product of burning fossil fuels. North America’s Environment, published by the World Resources Institute in May 2002 shows that the nitrous oxides that are emitted by power plants and automobiles eventually end up in rivers, streams and ultimately the oceans

• In Dead Water, edited by C. Nellemann and published by UNEP in 2008 explains how coastal development is expected to impact over 90% all inhabited coasts by 2050 and how such development will contribute to more than 80% of all marine pollution.

• Ordinary everyday litter, irrespective of its origins, can end up in the world’s oceans, transported there by major inland waterways, such as the Mississippi/Missouri waterway system in the United States. The" National Marine Debris Monitoring Program Report" published by Ocean Conservancy in 2007 highlights plastic and synthetic materials as being the major ocean polluters since they are very slow to breakdown and can remain in the marine environment for hundreds of years.

• Blue Carbon, edited by C. Nellemann and published by UNEP in October 2009 shows how climate change and increasing atmospheric levels of carbon dioxide are changing the pH of the oceans. It goes on to detail how this acidification of the marine environment will have very negative impacts on ocean biodiversity.

Ocean Dead Zones

One of the most dramatic results of the relentless rise in marine pollution is the increase in both the number and size of ocean dead zones:

• Dead Zones, by Reyes Tirado and published by Greenpeace in 2008 defines ocean dead zones as areas of the ocean which have been depleted of oxygen. Excess nutrients from inland waterways encourage algae growth, which uses up all the available oxygen. This lack of oxygen ensures that no marine life can exist in such areas.

• Once confined to such heavily industrialized areas as the Gulf of Mexico and the Black Sea, Global Environmental Outlook 4, now says that marine dead zones are present in Asia, Africa and South America as well as the heavily industrialized North American continent.

• One of the original dead zones, that in the Gulf of Mexico, is growing at an alarming rate. Heal the Ocean, by Rodney Fujita and published by New Society Publishers in 2003 shows that this dead zone had grown to an area of 8,000 square miles by 1999 and the author claims that the rising economic growth since 1999 can only have added to its size.

• Rashid Hassan, author of Ecosystems and Human Well-being, published by Island Press in 2005 argues that the relentless push for economic development and the need for more artificial fertilizers to feed an ever increasing global population has led to a doubling of ocean dead zones every decade.

It is obvious that unsustainable economic development, intensive farming and the growth of carbon dioxide emissions are causing irreversible environmental changes in the world’s oceans. The marine ecosystem, already under threat from global warming, will have to be protected from all forms of pollution.

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