Reviving the Reef

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On the 16th October, the Sun published an article claiming that, after 8000 years, the Great Barrier reef had died. This demise of the largest life form on the planet led to widespread mourning on social media. However, these claims were over-exaggerated and even though the future of the world’s reefs seems to be a bit bleak, there is hope yet.

When it is said that the Great Barrier reef is in ‘severe stress’, it is vastly different to the stress that humans undergo. Environmental stress brought on by global warming causes corals to disperse all of the colourful algae living within them.  The result is that the coral becomes white, a process known as bleaching which may take a change in sea temperature of as little as a 1˚ C to happen. Not only does this severely affect the coral, causing the coral to become weaker and more susceptible to disease, it also has an impact on the entire ecosystem that uses corals as a base.

That is not the only environmental issue that has an effect on these colourful and phenomenal life systems. Increasing carbon dioxide levels lead to ocean acidification, making it difficult for corals to grow. The acidic water means that corals cannot absorb the calcium carbonate they require to build and maintain their skeletons, causing them to eventually dissolve.

All this (and more) has led to one of the main attractions of Australia going from the thriving and vibrant underwater city it was, to a place filled with death and despair; a fate seen all over the world in various corals. However, there has been research suggesting that there is more resilience in the oceans than we previously thought.

A promising approach to saving coral reefs is known as ‘fragmentation’. Fragmentation (and the newer micro-fragmentation) have been used in conservation for up to 11 years already. Unfortunately, the process requires time, labour and money. On a basic level, it involves cloning parts of coral and then reintroducing them into the wild in the hope that they will settle and grow over the old coral, rejuvenating it. This has been done in the Florida Keys where 200 micro fragments were introduced 3 years ago and are now 6-8 times bigger and have joined together into sections. From there, researchers Dave Vaughan and Chris Page have introduced around 10,000 pieces into the wild.

The issue with using cloned corals is that they are all genetically identical, meaning that they can succumb to the same environmental stresses. You could put all this work into cloning and planting thousands of fragments and the next environmental issue could wipe it all out.

Like any strong ecosystem, diversity is essential. Vaughan and Page are growing 20 to 30 genetic variants of coral to address this issue, but another researcher, Peter Harrison, is investigating the possibility of taking two sexually active corals, waiting for them to reproduce and collecting the offspring to introduce into the wild. This idea was previously used in Australia in the late 1990s and Palau between 2007 and 2009. These teams released the progeny onto healthy corals under mesh sheets, and although thousands settled, most of them died within 30 weeks. It was suggested that this was due to overcrowding as the reef was healthy and so, in 2013, Harrison and his team found a severely damaged coral in Magsaysay and tried again. Even though the initial results were not promising, with most of the settlers dying within 6 months, by 9 months those that had survived were settled populations and within three years they had reached sexual maturity.

The scientific concept of survival of the fittest applies here. Some of the corals have been able to cope with environmental difficulties better than others; these have been nicknamed ‘super’ corals. Ruth Gates has been collecting these ‘super’ corals and breeding them in her lab to create corals that will be able to cope with the next big bleaching event. The idea is to create a coral that will be able to cope with the changing seascape without human intervention.

There is, though, another organism that has the potential to help – fish. Even though fish can be seen as destructive when they knock over young coral, they can also help to nibble away at algae that might cover the newly planted coral, preventing growth. This was noted in the Seychelles, in research led by Sarah Frias-Torres. The project involved growing branching corals for transportation. These were grown on ropes that had to be scrubbed by hand in order to keep the young coral from being overgrown. The researchers noticed that certain types of fish were attracted to the growing coral and ate the algae that threatened it. This observation was also made when the coral was moved into the wild. After transporting 10,000 corals, fish started appearing on the reef. At first, they knocked over 16% of the reef, but the team eventually established a system that appears naturally in order to reduce destruction. While this was successful in the Seychelles it may, once again, not be suitable everywhere.

At the end of the day, there is no ‘one size fits all’ approach to saving corals. Each will require a different combination of the newest techniques due to the variety of threats they face as well as their own needs. Even though coral fragmentation, reseeding and selective breeding come with their own advantages and disadvantages, the potential that they have shown and the willingness of coral to stay alive gives a glimmer of multi-coloured hope for the future.

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