By: Floro Mercene
The Great Barrier Reef, off the coast of Queensland in northern Australia, has long been one of the world’s most magnificent natural wonders, and it is the world’s largest living structure even visible from outer space. The 2,300km-long ecosystem comprises thousands of reefs and hundreds of islands made of over 600 types of hard and soft coral. It is home to countless species of colorful fish, mollusks and starfish, plus turtles, dolphins and sharks.
But now, huge sections of the Great Barrier Reef, stretching across hundreds of miles of its most pristine northern sector, were recently found to be dead, killed last year by overheated seawater. Perhaps, coral is the most vulnerable to temperature change among the ocean organisms. More southerly sections around the middle of the reef that barely escaped then are bleaching now. Bleaching slows coral growth, makes them susceptible to disease, and can lead to large-scale reef die-off.
In 2015, nearly all observed ocean surface temperatures registered above average because of El Nino combined with human-induced warming. 2016 was the third consecutive hottest year on record. Since 1955, more than 90 percent of excess heat retained by the Earth as a result of increased greenhouse gases has been absorbed by the oceans. Warmer temperatures are threatening some marine animals and plant species, like the bleached coral on the Great Barrier Reef.
Changes in sea temperature could affect many species’ successful breeding. Research has shown that krill (called ‘alamang’ in the Philippines), for example, reproduce in significantly smaller numbers when ocean temperatures rise.
Krill is an extremely important link at the base of the food chain. This can have a cascading effect by disrupting the life cycle of many larger animals such as penguins and seals for whom krill makes up the largest part of their diet – which in turn causes food shortages for higher predators.
(To be continued)
