Corals are essential for healthy oceans. Will they disappear because of pollution and climate change?
The oceans are home to some exceptional fauna and flora but in recent times they have become more fragile as a result of pollution and global warming. Coral reefs also contain a huge part of life. The Great Barrier Reef alone accounts for 10 % of the world's marine biodiversity. Corals are small marine animals with a limestone skeleton and tiny tentacles and are of significant importance to nature. The polyp (another name for coral) lives by settling on oceanic minerals. This immediately explains its importance: many species can take shelter in coral reefs and also feed and grow there. About 25 % of underwater creatures live in these reefs.They are important for other reasons as well. Shoreline reefs partially absorb wave power, preventing land erosion and creating new areas for underwater life (lagoons, for example).
However, coral reefs have been suffering from intense bleaching for 30 years, resulting in a higher coral mortality rate. This bleaching is due to excessive thermal variations causing the coral to reject its microalgae, which contain essential nutrients. The absence of these microalgae causes the coral to bleach and weakens it, especially considering the predicted changes in temperature, eventually leading to the marine animal's death.
Today, global warming is affecting all oceans and scientists predict that 90 % of corals will die by 2050. Despite these challenges, it is found that corals can survive bleaching: recent research has shown that they can heal at a depth of 40 meters. In the event of a permanent increase in temperature, there is, however, no guarantee that our coral reefs will survive. Although UNESCO has removed the Belize Coral Reef from the list of threatened sites, 15 of the 29 World Heritage sites have experienced thermal stress since 2014.
60 million dollars
From a scientific point of view, the study of coral immunology is the key to understand their health and to preserve corals more efficiently. In early 2018, the Australian government released 60 million dollars to protect and study corals. But this amount is insufficient in order to address the root cause of the problem, which is global warming. Natural regulation is obviously a part of that. Seabirds, whose droppings feed the corals, also play an important role. But the impact of coral destruction extends far beyond the waters. It is also about preserving thousands of direct and indirect jobs, particularly in the tourism sector.
Various actions have already been undertaken to prevent the extinction of corals. One example is Ecopora, a coral breeding farm in Belgium founded by two students, Edouard Vangangel and Julien Glinne. Their objective is to cultivate coral using the cuttings technique directly in Belgium, in order to avoid coral harvesting and shipping. It is estimated that today 1.6 million corals are being removed from their natural environment for the sole purpose of decorating aquariums (fish-keeping). This local culture provides corals with better growing conditions and prevents the degradation of their natural environment.
It is estimated that today 1.6 million corals are being removed from their natural environment for the sole purpose of decorating aquariums (fish-keeping).
A second project initiated by Professor Igor Eeckhaut (University of Mons) along the northern and southwestern coasts of Madagascar, was set up between 2012 and 2016. The objective was to develop eco-friendly aquaculture by building ponds for algaculture and coral aquaculture. Scientific support has made it possible to study the follow-up of algaculture and coral aquaculture to improve their efficiency. This activity now provides local populations with an alternative income to fishing and hunting.
In the event of a status quo, the UNESCO report points out that coral reefs will continue to undergo annual bleaching, followed by a limited period of recovery. This situation would lead to a deterioration in their living conditions and would disrupt the entire coral ecosystem. As stipulated in the Paris Agreement, an increase limited to 1.5°C would prevent the annual bleaching of the 29 coral reefs on the World Heritage List, ensuring them a sustainable future.
Sunscreens, hidden poison for oceans and corals
We have no choice than to protect our skin from UV rays when sunbathing. However, the used sun creams spread easily in the oceans. Unfortunately, the chemical filters that make up these creams contribute to the deterioration of corals. Of course, we cannot stop using them, but some brands are looking for less polluting products. The most sound solution has yet to be found, but we can act by reducing our exposure to the sun, protecting ourselves with a parasol or light clothing, or limiting the application of cream in a reasonable way.