Oceans

Our oceans - the world's last great wilderness - are in crisis. Destructive fishing, polluting industries and climate change are threatening the survival of fish species, whale and dolphin populations and whole marine ecosystems.

Oceans cover more than two-thirds of earth's surface, and ocean life comes in an incredible array of shapes and sizes - from microscopic plankton to the largest of the great whales.

The number of different species living in the oceans is estimated to be at least 178,000, but this could be fraction of the true number, as deep sea exploration continually reveals more. They are all key parts of complex, interconnected marine ecosystems. We still have so much to learn about how these ecosystems work and the impacts our activities are having on them, but unless we act now there may not be time - latest research indicates that, if nothing is done to reverse present trends, stocks of many commercially fished seafood species are projected to collapse within 40 years.

And loss of fish from the oceans has harmful knock-on effects, including a deterioration of water quality, oxygen depletion, and higher numbers of toxic algal blooms (rapid temporary increases in microscopic plankton levels which can poison other marine life).

Thankfully there is some good news. In ocean areas that have already been protected, threatened species are returning and there is an overall increase in the variety of species present. And in areas just outside the reserves where fishing is permitted, big increases have been recorded on the size of the catch.

So it's up to us - we can plough ahead in a 'business as usual' manner and permanently damage one of our most precious resources, or we can pull back from the brink by establishing a global network of marine reserves and giving the oceans the breathing space they need to begin the recovery process.