Did You Know?!

Climate change is one of the greatest global threats to coral reef ecosystems today.  Coral bleaching rates have spiked, as well as the number of infectious diseases. Bleaching is when the These coral have lost their symbiotic Zooxanthellae, which are the symbiotic algae that live in the hard or stony corals in nature as well as the reef aquarium, due to heat stress, causing them to appear white (2). Additionally, carbon dioxide absorbed into the ocean from the atmosphere has already begun to reduce calcification rates in reef-building and reef-associated organisms by altering sea water chemistry through decreases in pH, which causes ocean acidification. If there is a failure to address carbon emissions, the impacts of rising temperatures, and ocean acidification could make many other coral ecosystem protection, basically, pointless. Much of the carbon dioxide that enters the atmosphere dissolves into the ocean. In fact, the oceans have absorbed about 1/3 of the carbon dioxide produced from human activities since 1800 and about 1/2 of the carbon dioxide produced by burning fossil fuels. As carbon dioxide in the ocean increases, ocean pH decreases, making it become more acidic. With ocean acidification, corals cannot absorb the calcium carbonate they need to maintain their skeletons and they will dissolve. Already, ocean acidification has lowered the pH of the ocean by about 0.11 units, making the ocean's acidity to a current pH of 8.069, which means the ocean is about 30% more acidic now than it was in 1751. If nothing is done to reduce carbon dioxide emissions into the atmosphere, ocean acidification will increase and more and more corals will be damaged or destroyed.

So why are coral reefs so important? Snails, clams, and urchins also make calcium carbonate shells and ocean acidification negatively impacts these organisms as well. Just like corals, ocean acidification makes it harder for these organisms to absorb the calcium carbonate they need to build their shells (1). The coral bleaching also makes it harder for fish to live in the reefs. Most of the brightly colored fish you see in the coral reefs are there to live in the colored coral to hide from predators. Likewise, bleaching causes the algae many organisms use as a food source to die off, leaving them desperate to find a new home.

Climate change also affects the coral reefs, such as the Great Barrier Reef in Australia, with much more intense weather. Flood plumes and cyclone Yasi affected very large areas of coral reefs in the Great Barrier Reef Marine Park. Cyclone damage was both severe and widespread, and approximately 6 of the reef area in the Marine Park suffered severe damage, with broken corals reported across an area exceeding a little over 55,000 miles of the reef.

1.       http://www.teachoceanscience.net/teaching_resources/education_modules/coral_reefs_and_climate_change/how_does_climate_change_affect_coral_reefs/

2.       http://coralreef.noaa.gov/threats/climate/

3.       http://www.gbrmpa.gov.au/managing-the-reef/threats-to-the-reef/extreme-weather