Coral reefs are known to support an entire ecosystem, however, they are also responsible for a substantial economic structure (e.g. real estate, medical, tourism and fisheries markets). Our world has been experiencing extensive coral mortality for some decades already. By 2030, 90% of the coral reefs are going to be threatened and by 2050, nearly all of our reef areas could be at risk, according to the US National Oceanic and Atmospheric Administration.
Why are the coral reefs dying?
Most of this extreme rate is the result of anthropogenic activities, such as climate change, overfishing, pollution and runoff from coastal development and agricultural areas. Extreme heat events can have a direct impact on coral bleaching, a process caused by the symbiotic microalgae expulsion from the coral. These symbiotic organisms give colour to the corals, and once they are gone, the coral structures turn into white and the bleaching can result in massive death rates. In addition to the temperature rise, ocean acidification might also threaten reefs by reducing growth rates and causing structure fragility.
Invasive species also pose problems for local coral species, such as disease dissemination and competition for resources. Invasions are often a result of direct human actions (e.g. ballast water discharge and underwater building), but also of indirect human actions (e.g. physical and chemical changes of the environment that favour invasive species establishment).
Overfishing can also affect the coral reef ecosystem. Reef fish are very important for coral development, by cleaning macroalgae from the reef surface and transporting resources (e.g. carbon and nitrogen). When fish populations are reduced, these macroalgae take over reef areas and kill corals. Once the corals are dead, fewer fish come. Thus, the algae rapidly take over extensive areas, which prohibits natural coral recovery.
Other human actions might also impact reef areas, pollution from industries and poorly planned coastal development are harmful to these ecosystems. Rivers driving materials, pollution from industrial centres and agricultural runoff to the oceans can also cause coral death, by contamination and sedimentation.
What can be done for the coral reef restoration?
There are many actions that we can take to protect reefs. Besides joining forces to call for policies that draw new guidelines for more sustainable human actions affecting marine environments, we can also support other movements for coral reefs conservation and recovery. We can work on making healthier fish community with sustainable fish consumption, more conscientious water usage and sewage treatment. CO2 emission reduction also helps in reducing impacts over coral reefs, due to reducing global warming and ocean acidification. Also, we can get involved with environmental initiatives and organisations, by volunteering, dive programs, using citizen science and taking part in courses and events. It is also possible to visit reefs responsibly and share experiences for coral reefs conservation and recovery. Social media are a great way to be part and help to save coral reefs by raising awareness of the coral’s importance and how human action might affect them. Moreover, through social media, we can establish a strong community which can support the actions, projects and organisations that are dedicated to being part of the solution, rather than the problem.
If the environmental conditions return to being favourable for the coral establishment, natural recovery might take decades to restructure a coral reef area. Furthermore, coral gardening is a very significant assistance for coral reefs recovery.
Have you ever heard about coral farms?
Coral farms are responsible for taking coral fragments and strategically regrowing them to restore degraded reef areas. The regrowth processes might take months or even years, depending on the nursery technique used. During this period, keepers maintain the best coral placement for natural conditions, sunlight and water flow. Once the corals are mature and healthy, they are moved to the wrecked coral reef area. Thus, these “new” individuals can rebuild and restructure the area once destroyed or threatened.
Nonetheless, new techniques have been developed aiming for a shorter coral growth period and larger-scale reef restoration. Unlike ocean-based nurseries, the land-based is based on micro fragmenting and lab processes. In addition to these diverse techniques, the avoidance of unfavourable conditions is a plus to land-based nurseries, such as predation, boat impacts, natural catastrophes, etc. Land-based farming has shown results of coral maturation almost fifty times faster than ocean-based farms. Additionally, scientists can also work on “environmental” conditions modulation, as temperature and acidification control. Thus, the “new” individuals to be placed on the reef can be naturally more tolerant to harmful conditions their “parents” once faced.
Is there technology in coral reef restoration?
Few other studies showed results for other techniques of “heat resistance” on corals. By laboratory symbiotic microalgae removal and manipulation, a “direct evolution” process is driven for the algae. This technique consists of exposing the organisms to increasingly warmer water temperatures. Thus, when reintroduced to coral larvae, the coral-algal symbiosis is more resistant to heating events, avoiding bleaching. To assist these regrowth techniques, a type of acoustic enrichment also helps to enhance the reef fish community around the re-establishing area. The sounds played are from a healthy reef area to restore the fish population. Thus, the area is cleaned by fish and corals have enough space for recovery.
There is also another way to sustain coral restoration, using artificial reefs construction methods and reorganising structures available in the environment. These methods consist of increasing habitat and reef structure for corals and other organisms to grow on. Normally, these methods are used on locals where solid structures were reduced due to environmental modifications caused by human actions or natural events. By providing a substrate where coral larvae can settle, the recruiting process can be exceptionally successful in favourable conditions.
A sunk vessel used as an artificial substrate for reefs’ species recruitment and larvae settlement area. Image by Alana Leitão.
Do we have any results?
Globally, coral reefs restoration efforts are bringing positive results for coral reefs health recovery and, thus, for marine ecosystems and economics. This is the result of best practices and movements organised by communities of scientists, managers, educators and the local population.
Remember: For coral restoration and recovery, it is important to take action on more sustainable activities to support ocean ecosystems conservation. Community engagement on supporting conservation organisations and on public policies discussions can raise voices for the oceans and help to preserve and restore them. We highly encourage anyone interested to join forces for coral reef restoration and conservation by searching an organisation to get involved.
We would like to read your opinion on which of the proposed approaches would work and why? Where do you see potential or obstacles? Or do you even see different possibilities? Do you disagree with any of the viewpoints or do you have other good news? Check out some of the work our partner projects are doing in the area of coral reef restoration:
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