As a marine biologist, I felt that writing on this subject would be a great chance to revisit old ideas while learning about new research.
Corals which are known for their charismatic colours and striking textures are home to diverse organisms. They also offer important services such as coastal protection, employment and food security for millions of people.
These remarkable organisms are also the classic textbook example of symbiotic relationships as they thrive together with microalgal symbionts that provide energy from photosynthesis. However, at present, there are a multitude of issues that threaten the health and survival of coral ecosystems.
Two of the most critical of these issues include the threats presented by global warming and ocean acidification. These environmental problems have already resulted in mass bleaching events for corals across different oceans, in different ecosystems.
As society trudges its way towards sustainability and slowly implements policy changes to address and combat global climate change, scientists have been working to understand the intricacies of coral health. Here’s a mix of management strategies, both conventional and quirky:
1. Reef restoration
Similar to forest restoration, the restoration of corals is a tried and tested method with both, advantages and disadvantages. Organisations such as the Reef Restoration Foundation utilise ocean-based coral nurseries from which they acquire coral fragments to assist the regeneration of damaged reefs. These restoration programs require plenty of research to prevent a loss of corals from donor sites and also a domination of a single species. In addition to using natural coral fragments, restoration efforts also utilise artificial reefs, sometimes 3D printed. The benefits of artificial reefs are that it allows control of — and the ability to increase — the structural complexity of reefs. They also increase the available substrates for reef organisms. Reef restoration is still at a developmental stage where each of the techniques offers unique advantages and disadvantages. Similar to selecting an efficient reforestation or tree planting program, choose your reef restoration program wisely!
2. Identifying resistant genotypes
Another coral reef management strategy is to monitor reef resilience in response to climate change. This involves identifying the genetic traits in corals that may help them thrive and adapt in changing oceans. By identifying naturally robust species, conservation efforts can be optimized. In addition to identifying resistant corals, scientists are also using assisted evolution to develop heat-resilient strains of the algal partners in coral symbiosis. However, there may be a trade-off here: Heat tolerant symbiotic algae also reduce coral growth rates!
3. Studying coral immunity
Researchers are also studying mechanisms of coral immunity to identify how this can play a role in the ability of a coral to survive or perish. A key component of the immune system of reef-building corals is melanin production. This aspect of immunity which defends corals from disease causing organisms may now also be used to battle coral bleaching.
4. Sparking the seas
Mineral Accretion is a reef restoration method that uses low voltage electricity to increase the growth rates of corals. This method grows corals on metal cages that are then exposed to an electric current. The current results in the formation of chalk which is similar to the material coral skeletons are made of and has had a successful trial in Maldives. However, scientists have found variable results for this technique and suggest proceeding with caution when planning for reef rehabilitation.
5. Bots to the rescue?
In Australia, two robots have been developed to rescue the reefs – LarvalBot and COTSbot. The first, LarvalBot, gently releases microscopic coral offspring (larvae) to sites with damaged reefs and has an onboard vision system that allows for targeted larval distribution combined with tandem photo surveys. The second bot, COTSbot, coasts (excuse the pun) around the reef looking for crown-of-thorns starfish (COTS). The crown-of-thorns starfish feeds on coral and outbreaks have resulted in devastating impacts on the Great Barrier Reef. The COTSbot aims to remedy this by delivering fatal injections containing bile salts to crown-of-thorns starfish and allows reef recovery.
The intricate balance of coral ecosystems does not have an infinite capacity to thrive despite our abilities to identify resilient populations and genotypes. Ultimately, despite the best intentions and efforts of scientists, there is a need to fight climate change globally. The most innovative of research techniques at best buys us time by widening the window in which change has to be accomplished.