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Coral Reefs Under  Threat

Coral reefs are valuable ecosystems. Believe it or not, they are home to 25% of all marine life, which is over 2 million species! They provide an important barrier against extreme climatic events, where communities across the world consider their existence as essential, not only to ocean health, but also human wellbeing. Without any surprise, they are under threat and becoming a colossal distress for biodiversity. Here we explore why climate change and anthropogenic behavior are killing our coral reefs.

They are probably one of the most sensitive ecosystems, even tiny fluctuations in light, salinity and sea surface temperature will initiate coral bleaching. Due to coral reef’s biological diversity and high marine productivity, degradation is dramatic in terms of economic benefits from tourism the discovery of new biochemicals.

Flickr | USFWS - Pacific RegionCoral Bleaching

Some of you may be thinking what the term ‘bleaching’ means in this context. Well it’s simple; it’s the visible whitening of coral reefs due to the loss of symbiotic algae, an increasing crisis with changing environmental conditions. Unfortunately, climate change has overtaken all other factors leading to coral bleaching, this really is no surprise! This prompts persistent questions such as “Will coral reefs survive climate change?” The answer to this question is somewhat complex, as a lot of research is focused on both the amplification of bleaching with climate change and possible recovery and adaption of bleaching. At this moment in time, it is uncertain which of the two will occur, but with knowledge that coral reefs are sensitive to temperature rise, and the fact that sea surface temperatures are increasing with climate change, we already know danger is ahead.

Flickr | ARC Centre of Excellence for Coral Reef Studies 

Sea Surface Temperature

Coral growth is confined to 18-30°C oceans, any temperature above or below this threshold will dampen the growth of corals, specifically high temperature as this is a significant driver in bleaching episodes, occurring with minimal increases of even 1-2°C! Elevated sea surface temperatures promote destabilisation between the coral organism itself and symbiotic algae.

A lot of research focussed in the Caribbean Basin has indicated a correlation between bleaching episodes and increased sea surface temperatures from 1980-1990. Even a 0.1°C regional increase prompted a 35% upsurge in coral bleaching. This really does emphasise how sensitive coral reefs are! The same occurred in the Indo-Pacific Ocean, where researchers found thermal stresses from 1997-2006, indicative of climate change and linked to consecutive mass bleaching events. A lot of ocean temperature models have predicted the effect on coral bleaching, and it’s not looking good at all.

Flickr | GRID Arendal

Anthropogenic Interferences

It’s no lie that tourism itself is a threat to coral reefs. Have you ever thought about how many people visit the Great Barrier Reef a year; it’s 2 million, generating over $2 Billion (Australian dollars) annually! Think about the volume of people swimming in the waters, scuba diving or even snorkeling. Consider the number of boats sitting on top of the reefs, putting down their anchors without any consideration to the coral reef. All these instances are essentially threatening the ecosystem, but continue to do so for the sake of economic benefits.  Something has to be done promptly before there’s no reason for tourists to visit, as the entire system will become bleached.

The Maldives, as threatened as it is by climate change, is a key example of where humans have exacerbated coral reef systems. Areas of the islands where fishing is permissible have less coral cover than areas closed to fishing, supposedly linking human activity to coral bleaching. Though, a point to consider is that human activity is not as exacerbating to coral assemblages as climatic effects.

Flickr | stephenk1977

Coral Reef Recovery

The capacity for coral reefs to recover almost questions the role of climate change. Believe it or not, coral bleaching is reversible process, but not many people know it! The symbiotic algae within the host tissue can actually return to its pre-bleaching state. Although the Maldives has already been mentioned to have threatened coral reefs, it is one of the very few areas where there has been coral recovery since the 1998 mass bleaching event. Since then, there was been a 40% increase in coral cover, despite battles with elevated ocean temperatures and ocean acidification. In fact, the Indian Ocean coral reefs were still able to recover after the catastrophic 2004 Tsunami! To be able to survive an event on such an extreme scale, coral reefs are possibly not as delicate as people think.
A point to consider is that coral recovery does not occur in all coral reef systems. The Great Barrier Reef hasn’t shown any recover and only systematic decline in last 2-3 decades of about 50%. As already mentioned, tourism could be the reason for this!

Flickr | Georgia Tech College of Sciences


Although there’s no way to exactly alter the direct effects of climate change, there are so many marine conservation programmes which aid the health of coral reefs worldwide. Frontier have 54 marine conservation projects, all offering opportunities to go out into the field and see the threats to coral reefs for yourself, giving you the opportunity to  help conserve the precious ecosystem in Belize, Madagascar, Fiji and Tanzania and many more exciting destinations! Whether you’re completing snorkel surveys and mapping corals, identifying reef fish and invertebrates or studying the abundance of indicator fish species, you’ll have a once in a lifetime experience. For more information click the link!

Now you can understand the threat to coral reefs around the world, and it’s not going to get any better with climate change. Remember, you don't have to be a scientist to have a positive impact on coral reefs.


By Sophia-Harri Nicholaou - Online Journalism Intern

Frontier runs conservationdevelopmentteaching and adventure travel projects in over 50 countries worldwide - so join us and explore the world!

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