Spotlight: The Great Barrier Reef

Behold.. the Great Barrier Reef!

Off the northeast coast of Australia, it is the largest tropical coral reef system in the whole world! It stretches over 1,200 miles along the coast and the area of it is more about the size of 70 million football fields.. that’s half the size of Texas!

Almost 3,000 reefs built by over 360 different species of hard coral make an attractive home for a large variety of marine life. If you don’t believe me when I say a LOT of marine life, take a look at these numbers: 400 types of sponges, 4,000 kinds of mollusks, 1,500 unique fish species, 500 varieties of seaweed, and 800 kinds of echinoderms. Six of the world’s seven species of sea turtle call this place home, as do 30% of all soft coral varieties and hundreds of different sea birds!

Aside from being a wildlife metropolis, the corals also have other scientific uses. By drilling cores out of the reef, scientists can tell things about the past (much like rock core samples and geologists). They can tell things like sea levels, temperature, and ocean chemistry.

Currently, things aren’t looking so great for the GBR… rising sea temperatures and higher ocean acidity (the ocean absorbs excess carbon dioxide from the atmosphere) are bleaching the reefs. The reefs themselves are white, but the microscopic plants they form a symbiotic relationship with are brightly colored. The corals can’t take the changing conditions on top of the relationship with the plants (the benefits from their photosynthesis creates too many free radicals which actually can hurt the coral) and kick them out. Coral reefs all over the world are suffering the effects of bleaching and are also being destroyed further by more frequent hurricanes, storms, and pollution. Commercial fishing and impacts of the tourism industry are both heavily felt on the GBR as well.

While corals which have been bleached are not automatically dead, they sure look it. The loss of the plants they’d ejected to save themselves means they can’t get enough energy/food to survive. They’re starving. If the stressful conditions are fixed quickly enough, they can make a weakened comeback. However, the growth rates will be slower, less reproduction, and they will be more susceptible to diseases. It can take up to 20 years for a reef to recover from a bleaching event, if it does at all.

And it goes almost without saying that if the coral cannot survive, the rest of the sealife won’t be much better off. The rising temperatures kill off baby seabirds because the fish leave for cooler waters and the parents cannot find food for their chicks.Sea turtles, whose eggs are dependent upon temperature to determine the baby’s sex, will become almost entirely female. Without males, the species will not be able to carry on.

To combat the seemingly impending doom of coral reefs worldwide, some measures are being taken: some protected areas around ‘resilient’ reefs are being set up; a ‘Coral Reef Watch’ allows people to report instances of bleaching, and the Svalbard Seed Bank may soon house specimens which could be used to repopulate when the conditions return to an ideal state. 

Sources:

images: econews.com.au, australia.com, reefresilience.org

information: The Weather of the Future - Heidi Cullen