Reef madness - deadly theats to our coral ecosystems

Signal of change / Reef madness - deadly theats to our coral ecosystems

By Omar Gawad / 14 Aug 2016

The world’s coral reefs are facing turbulent times. Perhaps one of the worst affected is the Florida Reef; part of the Reef tract is dissolving at a higher rate than it can rebuild itself. The largest reef ecosystem in the continental US and the third largest in the world is vanishing at a greater rate than previously thought due to human-induced ocean acidification, caused when carbon dioxide (CO2) dissolves in water, causing a reaction which reduces the ocean’s pH level.

As acidity levels rise, limestone starts to dissolve and the structural integrity of coral reefs becomes weakened, making it easier for invasive organisms and plants to burrow into the living reef, turning it into their home and further destroying the ecosystem.

Past studies into acidification were conducted in controlled labs or on a small scale and thus incorrectly predicted that this erosion tipping point wouldn’t be realised until the middle of the century, when CO2 levels will be higher.

To further compound the stress of acidification, coral bleaching (caused by warm waters) and disease have plagued the reef – an increasingly global problem-, due to a combination of climate change and an uncharacteristically harsh El Nino in 2015. Although all of these phenomena are regular threats to reefs, they usually do not happen simultaneously. Bleaching occurs when the coral gets stressed when the waters start to reach around 30 degrees Celsius. While bleaching doesn’t kill coral outright, it weakens it and leaves it lacking in nutrients and very susceptible to bacteria and viruses, a much deadlier threat than bleaching.

So what?

There is a fear that this phenomenon will worsen as the summer of 2016 is due to be as hot, if not hotter than that of last year. Continual stress and damage may not give the coral enough time to repair itself.

The negative effects reach beyond the reef itself. Fish and other marine life will directly suffer as the collapse of a natural ecosystem will have serious implications on all surrounding wildlife. Indirectly, Florida’s local economy will feel the impact of the change that is happening underwater too. Reef-related tourism accrues the region nearly $3 billion per year according to Chris Langdon, chair of the University of Miami’s Department of Marine Biology and Ecology. This will bring serious implications for those in the surrounding areas, as many rely on tourism as the sole source of their revenue. Unfortunately, the threat to reef life stretches further than Florida. A quarter of all marine fish and 500 million people’s livelihoods depend on healthy, thriving reef ecosystems.

Reefs are facing imminent extinction over the next few decades; 19% are already dead. The Florida Reef is the canary down the mine, a prophetic warning of what the other coral reefs are facing in the not too distant future. If we continue on our current course, bleaching and acidification are set to increase in severity, however, we can mitigate these conditions and their effects on the reefs. While it is difficult to contain and control coral diseases, we can be more active in determining how susceptible coral is to them. Lowering collective CO2 output, the prime cause of both of these threats, will give our reefs a great insurance policy for the future, as will aiming for a 1.5 degree cooler world.

As morbid as the notion is, sometimes it takes a great tragedy in order to awaken public awareness and support. The good news is that it is still not too late to change this situation. If ocean conditions are normalised, coral can calcify, going through the process of rebuilding itself following a bleaching event. 45% of reefs are in good health and we still have time to reverse the damage done to the rest before it becomes a permanent reality

Image: Kent Wang / Flickr


The Washington Post –‘The biggest coral reef in the continental U.S. is dissolving into the ocean’, (4th May 2016)

The Washington Post – ‘Bleaching and disease are devastating the biggest coral reef in the continental U.S.’, (26th October 2015)

The Washington Post – ‘Scientists say a dramatic worldwide coral bleaching event is now underway' (October 8th 2015)

Worldwatch Institute-'Coral Reef Loss Suggests Global Extinction Event'

What might the implications of this be? What related signals of change have you seen?

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