Although this is obvious to many scientists and nature enthusiasts, many laymen are painfully aware that corals are very ancient marine animals in their own right, just like fish inhabiting seas and oceans, although they do not do not correspond to a known classical anatomical diagram. Composed of an exoskeleton, coral exists in different appearances.
Approximately 1,300 species of coral have been identified to date in the Pacific, Indian and Atlantic oceans. Corals live in symbiosis with a microscopic unicellular alga: zooxanthella and form one of the most threatened ecosystems on the planet.
This unique biotope could well be the source of major environmental upheavals for future generations. Indeed, far from the postcards for tourists on which the mosaic of reef colors is displayed, the coral is dying a little more each day. It is estimated that 15% of the world population is directly dependent on the good health of corals.
Corals are particularly fragile and do not tolerate even the smallest physical and chemical variations in their environment.
Decline in coral reefs: a multifactorial origin
The discharge of industrial and urban wastewater is responsible for the high levels of phosphate, nitrate and pesticides in the seas and oceans. These toxins strongly disturb the reproduction of corals.
In 2017, the International Union for the Conservation of Nature, estimated at 10 million tonnes / year of plastic waste discharged into the oceans . This contamination promotes the occurrence of coral pathologies. According to a study by Cornell University in Ithaka in the United States, 4% of corals not exposed to plastic develop pathologies against 89% for corals covered by this type of waste.
On the same subject :
- Coral reefs are (too) close to us
- Disappearance of corals: the “most beautiful colors of death”
- Keeping Europe’s seas and oceans safe, clean and healthy
- Belize’s coral reef no longer threatened by oil exploration
According to the Environmental Health Perspectives, 4,000 tonnes of sunscreen are released into the world’s seas and oceans each year. Sunscreens containing chemical filters contain anti-UV components harmful to corals since they increase the risk of infection causing the destruction of the symbiotic zooxanthella seaweed, essential for the development of coral.
The impact of oil spilled “accidentally” during oil spills by oil tankers on the marine fauna is no longer demonstrated.
Poorly controlled urbanization policies
The intensive exploitation of the seabed destroys this ecological niche of coral reefs at lightning speed. The damage being irreversible, the responsibility of the mining companies is beyond doubt.
Although the cause and effect link is not obvious at first glance, the meteoric disappearance of forests results in an increase in the transport of sediments in the rivers which eventually reach the seas and oceans. This has an impact on the turbidity of the water and significantly reduces the penetration of light, directly affecting the photosynthesis of algae, which has a direct impact on the under nutrition of corals.
In Madagascar, the islanders would damage the coral by walking directly on it to fish for octopus and other shells and would use unsuitable fishing equipment . The overfishing of sharks play a crucial role in the food chain of coral reefs, since their disappearance promotes the proliferation of harmful invasive algae to the coral and it also becomes more vulnerable to predators including sharks normally feed. Dynamite fishing in the Philippines causes direct damage to the very structure of the reefs.
An increase of + 1 ° C in the surface water for two weeks is enough to cause the death of the coral, which results in the phenomenon of bleaching. For several years, the El niño phenomenon has become more and more frequent and becomes more and more intense, causing an abnormal and repeated rise in temperatures. The increase in the CO 2 content in the atmosphere causes the acidification of ocean water, which inhibits the production of calcareous exoskeletons of corals.
Why is the protection of coral reefs crucial for the future?
- The primary role of the coral reef is to physically protect the coasts from cyclones by absorbing from 70% to 90% the power of the waves. Erosion is thus limited and agricultural and tourist activities then become possible.
- Coral reefs are home to 30% of marine biodiversity . 1 km 2 of coral reefs can produce between 10 to 15 tonnes of fish. They therefore represent a vast food reservoir for island populations who derive their protein intake almost exclusively from the consumption of fish.
- For scientists, the coral reef represents a precious genetic bank from which molecules of interest are extracted in the development of tomorrow’s treatments for certain pathologies such as Cancer and AIDS.
What solutions can be envisaged on an individual scale?
On an individual scale, small gestures can make the difference in the long term. Among them, we can think of favoring sunscreens with mineral filters which are harmless to humans and have a very limited impact on coral. Mexico is a pioneer in banning chemical filter sunscreens containing two particularly harmful molecules: oxybenzone and octinoxate . Other regions of the globe such as Hawaii may soon follow this pattern.
Regarding scuba diving, it is essential to ban wild dives and promote eco-responsible tourist sites whose preservation of coral reefs is an absolute priority. In the Philippines, in the Tubbata natural park (listed as a UNESCO World Heritage site for 25 years), the number of divers is limited to 3000 / year to allow the coral to recover.
Decline of coral reefs: the cry of distress of the oceans
If the wonder alone is no longer enough to raise a collective and massive awareness of the importance of saving as quickly as possible the coral reefs still intact, let us hope that the concrete facts and figures can contribute to a salutary start in favor of preserving the bottom of our oceans. Perhaps the education system should be given a prominent place in environmental education in order to educate the generations of tomorrow on ecological priorities. Despite a critical situation, it is unthinkable to date to give up the fight and to resolve to the idea that future generations can never know this ecosystem. No doubt that the disappearance of this heritage would be tragic for the survival of many species