Part 3. What is whitening and what are the main dangers threatening coral reefs?
Coral reefs are an ecosystem with a high biological diversity. The symbiotic relationship between all reef organisms is the basis of a balance that is as subtle as it is powerful. If one of these organisms goes into pain or disappears, the entire functioning of the reef is affected.
Recent studies have shown that if coral reefs have gone through major climatic changes over time, it is because they have been set up slowly, allowing adaptation or even resilience of the coral ecosystem.
Today, ocean temperature is a major immediate threat. If coral reefs are able to adapt to a warming of surface waters for a limited time of one to two weeks, beyond, their ability to survive is affected.
The high level of oceans temperature and the acidification causes the rapid proliferation of algae, preventing the light from penetrating deeply. The photosynthesis essential to the survival of the coral can not be done properly. Some varieties of algae will also settle, come to cover and smother the corals little by little.
The combination of these factors, climate change, acidification caused by the increase of carbon dioxyde in the atmosphere, high temperature, algae and pollution phenomena, -related to the discharge of sewage and wastewater in areas of strong tourism influence and human activity-, puts the coral reefs under permanent tension. In the face of the stress he experiences, he expels the zooxanthellae and deprives himself of his main source of food that this symbiotic algae provides to him. The polyps die and the bleaching gives way to the beautiful life that prevailed until then.
On some reefs fishing techniques, particularly destructive with dynamite, have created and still create major damages. The use of Cyanide to collect rare species for aquarium owners are crimes to denounce with the greatest force.
What about so-called “natural” phenomena?
The destructive waves caused by typhoons or hurricanes by breaking large pieces of coral, give way to a break rug on which it will no longer be possible to reimplant coral or see the coral restart. The rubble is not stable or strong enough to allow the reef to re-establish itself. On the contrary, it is the algae, which are faster in their development, that will colonize these lost spaces.
Just as heavy rains eroding island soils lead to muddy flows in the sea laden with nutrients that settle and choke the corals. He enters suffering and bleached. A process that can be very fast. In the space of six months, a coral reef can die.
Coral reefs also have marine species – in a healthy environment that balances out of itself – these are not a problem – that become predatory. This is the case for example parrotfish bumphead, whose colonies, when they become too large can have a detrimental influence on the reef. Some animals such as Mantas rays but also Sharks whales that feed on the eggs expelled by the corals during breeding can also accentuate the suffering of an already vulnerable reef.
The Crown of Thorns Starfish (COTS) is also a formidable predator. It settles on the corals and feeds on their flesh. A single starfish can consume up to 2 to 6m2 of coral per year. The development of COTS, which knows no predator because of its poisonous spines, (except exception : Triton Snail eat COTS, but he is himself threatened by man who fished him for shell collectors or jewelry making) is very fast. Large areas of the coral reef in Australia and also in Indonesia are affected. At the present time, to stop the progression of COTS, the injection of a lethal solution directly into the animal prevails in Australia. This method prevails in order to avoid the dispersion of COTS eggs during a sampling of the live animal.
For observing COTS in action at KOMODO Nord on Acropora coral tables, the damage done is terrifying .
Drupella Snail, who also feeds on coral polyps, is responsible for blistering damage. Difficult to remove this guy because it is lodged in the tight branches and DS leaves behind its passage large white traces easily identifiable. In one area, we can find dozens or hundreds of this one. Even if it’s a small shell, it is a formidable predator!
Part 4. What can we do? Solutions no more destruction !💪