Facts and figures on marine biodiversity

  • The ocean constitutes over 90% of the habitable space on the planet.
  • 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.
  • Today 60% of the world’s major marine ecosystems that underpin livelihoods have been degraded or are being used unsustainably.
  • Marine Protected Areas (MPAs) are essential to conserve the biodiversity of the oceans and to maintain productivity, especially of fish stocks. World Heritage marine sites represent in surface area one third of all marine protected areas.
  • Approximately 12% of the land area is protected, compared to roughly 1% of the world ocean and adjacent seas.
  • Tiny phytoplancton provide 50% of the oxygen on earth and form the basis of the ocean food chain up to fish and marine mammals, and ultimately human consumption.
  • Ocean acidification may threaten plankton, which is key to the survival of larger fish.
  • If the concentration of atmospheric CO2 continues to increase at the current rate, the ocean will become corrosive to the shells of many marine organisms by the end of this century. How or if marine organisms may adapt is not known.
  • Ocean acidification may render most regions of the ocean inhospitable to coral reefs, affecting tourism, food security, shoreline protection, and biodiversity.
  • 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.
  • Today, fisheries provide over 15 percent of the dietary intake of animal protein.
  • 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.’
  • Agricultural practices, coastal tourism, port and harbour developments, damming of rivers, urban development and construction, mining, fisheries, aquaculture, and manufacturing, among others, are all sources of marine pollution threatening coastal and marine habitats.
  • Excessive nutrients from sewage outfalls and agricultural runoff have contributed to the number of low oxygen (hypoxic) areas known as dead zones, where most marine life cannot survive, resulting in the collapse of some ecosystems.
  • There are now close to 500 dead zones covering more than 245,000 km² globally, equivalent to the surface of the United Kingdom.
  • Coastal systems such as such as mangroves, salt marshes and seagrass meadows have the ability to absorb, or sequester, carbon at rates up to 50 times those of the same area of tropical forest.
  • Total carbon deposits in these coastal systems may be up to five times the carbon stored in tropical forests.
  • Between 1980 and 2005, 35,000 square kilometers of mangroves were removed globally.
  • Between 30 and 35 percent of the global extent of critical marine habitats such as seagrasses, mangroves and coral reefs are estimated to have been destroyed.
  • 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.
  • Further research and collective action is needed to mitigate the underlying causes of the loss of biodiversity. 
  • The Blueprint for ocean and coastal sustainability includes proposals to address these issues.
Back to top