Great Barrier Reef coral 'bleaching' level increased

Authorities in Australia have raised the threat level for coral 'bleaching' in the Great Barrier Reef, after divers found that lots of coral had died.

The Great Barrier Reef is the world's largest living structure, and is home to thousands of plants and animals - it is so big it can even be seen from space.

Divers have found that an increase in the sea's temperature has been putting the coral which grows there under a lot of stress causing 'bleaching', which means a loss of colour.

What is bleaching?

Many types of coral have a special relationship with tiny algae that live in the coral.

These tiny algae produce about 90% of the food the coral needs to grow, and give them their bright colours.

Bleaching happens when sea temperatures get too high or low, causing the algae to get 'stressed out' and leave the coral.

This turn the coral white and leaves it very vulnerable.

An increase of just one degree Celsius for four weeks can cause bleaching. If this continues for more than eight weeks, the coral can die.

Has this happened before?

In 2002 the surface temperature of the sea water in the Great Barrier Reef increased by around 2-3 degrees causing one of the worst bleaching incidents on record, affecting more than 60% of the coral.

While some coral reefs can recover from bleaching in a few years, others don't recover at all.

The Great Barrier Reef Marine Park Authority have now raised the bleaching threat level, and have said that there is a very high risk of mass coral bleaching this month.

The Australian government said it is working closely with the marine rangers to help keep an eye on the coral for the next few months to see how it is doing.

From CBBC Newsround

Europe's rarest seabird 'faces extinction'

Europe's rarest seabird will be extinct within 60 years, according to a new analysis.

The bird breeds in caves off Mallorca

Urgent action is needed to stop the Balearic sheerwater being drowned in fishing lines and nets, say scientists.

The bird breeds in the Balearic Islands, sometimes stopping off in British waters as it migrates north.

Research shows the global population is not sustainable in the long term. There are about 3,000 breeding pairs left.

The main threat to the bird is becoming entangled in fishing gear, according to findings published in the Journal of Applied Ecology.

Other risks include hunting by the likes of cats and other small mammals.

Prof Tim Guilford of the Department of Zoology at the University of Oxford is co-researcher on the study.

He told BBC News: "The survival of adults from one year to the next and especially of young adults is much lower than we thought.

"The species is unsustainable - it is on the road to extinction."

Night fishing

Estimates suggest about half of deaths in adult birds are due to accidental capture in fishing lines and nets.

Fishing on the seabed is a particular risk as birds can become entangled and drown when lines are immersed, say researchers in the UK and Spain.

Changes such as setting fishing gear at night when the bird does not dive "could make a massive difference", said Prof Guilford.

"The science shows just how serious the problem is, but also that there is a technically simple solution - the setting of demersal long-lines at night," he added.

The Balearic shearwater (Puffinus mauretanicus) is one of the rarest seabirds in the world.

The seabird is classified as critically endangered on the IUCN Red List of species.

It breeds on cliffs and small islets and lays only one egg.

From BBC News-Science / Environment