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Marine Biodiversity

The ocean constitutes over 90% of the habitable space on the planet and supports a multitude of life forms, from the blue whale, the largest animal on the planet, to tiny microorganisms, including the phytoplankton that provide 50% of the oxygen on earth.

Marine biodiversity provides basic goods and ecosystem services that are crucial to human life and to the reduction of poverty.

  Marine biodiversity is essential for life on earth. We must act today to protect it for the future.      

Irina Bokova, UNESCO Director-General, on the International Day for Biological Diversity 2012

As biodiversity declines, so too does the resilience of our ecosystems, which have been dramatically transformed as a result of human action. This year, the International Day for Biological Diversity is celebrated under the theme 'Marine Biodiversity' to increase understanding and awareness of these issues.


Today 60% of the world’s major marine ecosystems that underpin livelihoods have been degraded or are being used unsustainably. Pollution from sewage outfalls and agricultural runoff has contributed to the increasing incidence of low oxygen (hypoxic) areas known as dead zones, where most marine life cannot survive, resulting in the collapse of some ecosystems. Commercial overexploitation of the world’s fish stocks is so severe that it has been estimated that up to 13 percent of global fisheries have ‘collapsed.’

Ocean acidification, a result of carbon emissions, is affecting coral reef growth as well as some species’ ability to reproduce; it also may threaten plankton and zooplankton species that form the base of the marine food chain. Additionally, technological change and the emergence of new economic opportunities such as deep sea mining, more intensive fishing, and deeper oil and gas drilling increase risks to areas that historically were not under threat.

We must rise to the complexity of the challenge. To do so, we must target the underlying causes of the loss of biodiversity. Further research and collective action is needed.

UNESCO's actions to protect marine biodiversity

UNESCO believes that science in support of sustainable management is the cornerstone of the preservation of our ocean and its resources.

The UNESCO Intergovernmental Oceanographic Commission is managing the Ocean Biogeographic Information System, part of the International Oceanographic Data and Information Exchange. Building on a decade-long census of marine life, these powerful tools provide quantitative baselines of biodiversity at the regional and global level.

The Intergovernmental Oceanographic Commission works with States to conserve and use sustainably biological biodiversity in all marine areas. It is providing the scientific basis for a global inventory of ecologically and biologically significant marine areas in need of protection. This work is moving ahead with UNESCO’s network of World Heritage marine sites, which represent in surface area one third of all marine protected areas. It is undertaken also with the marine and coastal biosphere reserves under UNESCO’s Man and the Biosphere Programme, to promote the use of ecosystem-based approaches and marine spatial planning.

UNESCO is committed also to supporting the contribution of local and indigenous knowledge to the conservation of marine biodiversity, including for small island areas.

Facts and Figures

  • An estimated 50-80% of all life on earth is found under the ocean surface.

  • By the year 2100, without significant changes, more than half of the world’s marine species may stand on the brink of extinction.

  • Marine Protected Areas (MPAs) are essential to conserve the biodiversity of the ocean. Only 1% of the ocean is protected.

  • World Heritage marine sites represent, in surface area, one third of all marine protected areas.

  • Coral reefs are the nurseries of the oceans, they are biodiversity hot spots. On some tropical coral reefs, for example, there can be 1,000 species per m².

  • Total carbon deposits in coastal systems such as such as mangroves, salt marshes and seagrass meadows may be up to five times the carbon stored in tropical forests.

Rising Tides. Biosphere Reserves

Source: UNESCO Multimedia Archives


Celebration in the United Nations