Wave goodbye to the reefs.

We often hear about coral reefs being the rainforests of the sea - both habitats are packed full of thousands of species and sadly both are being lost at ever more alarming rates.

And this week we've heard a piece of really bad news for coral reefs, because they may be disappearing much more quickly than we thought they were, and possibly around twice as fast as rainforests.

That's according to a new study from John Bruno and Elizabeth Selig at the University of North Carolina in the United States.

They collected together over six thousand other studies going back to 1968 that documented how much hard coral was growing on particular coral reefs in the Indian and Pacific Oceans, in countries including Indonesia, Australia and the Philippines.

Hard corals are the building blocks of reefs - also known as scleractinia - they provide the main structure and habitat for all the other animals and plants to live on. Measuring the percentage of the reef that hard corals cover is one of the best ways of gauging how healthy a reef is. [It's a little bit like measuring how much canopy a rainforest has from either air born or satellite images, which is how scientists measure how quickly forests are being lost.]

The bad news is that the coral cover on reefs in the Indian and Pacific Oceans over the last 20 years has dropped by an average of 1% every year which might not sound a lot but it's the equivalent of around fifteen hundred square kms every year.

The study also discovered that reefs in the Indian and Pacific oceans also began declining much earlier than we used to think - it was always thought that reefs on the other side of the planet in the Caribbean were in the worst state, but now it seems the Indo-Pacific is also fairing just as badly.

The cause of these declines could be a combination of global factors, like increased sea surface temperatures that trigger devastating bouts of coral bleaching, as well as more local pressures like damaging fishing techniques and the run off of sediments and pollutants from land.

But it's not all doom and gloom. The researchers found that a number of reefs have in fact been increasing in coral cover, showing that it's not too late, especially if we start taking direct action to stop the decline continuing at all these different levels from local to global.

Protecting reefs makes nothing but good sense. Not only do the reefs of the Indo-Pacific contain huge numbers of species, the reefs also provide a crucial source of protein for people in many developing countries, they help protect coastlines from erosion and the generate important income in countries with burgeoning tourism industries.