Australian researchers caught on film a coral bleaching moment, being the first ones in the entire world to capture the sad event while taking place.
The video shows how coral react to hyperthermal stress, spiting algae and shrinking in size.
Coral bleaching is a global concern for researchers because it’s the main cause of death in coral reefs. The phenomenon is brought along by climate change. The increase in the water temperature stresses the corals and makes the algae leave the coral tissue which remains completely white.
In the US, the most important coral bleaching event took place in 2005, when half of the Caribbean coral reefs were lost in just one year. The marine biologists believe it was due to the warm waters that expanded south of the Antilles.
The video released last week was recorded by the scientists from the Queensland University of Technology. It shows the mushroom coral Heliofungia actiniformis changing its shape and expelling algae while being subjected to simulated warming conditions. The video follows the changes taken place during eight days, at the end of which the mushroom coral remains shrunken and with fewer algae than a week earlier.
The relationship between the coral and the algae is a perfect example of symbiosis. The coral polyps offer protection and a home of the zooxanthellae algae, which in turn provide color and nutrients to the corals.
The bleaching process can take up to ten days, and it’s provoked by even a slight increase in temperatures over the thermal comfort zone of the corals.
The researchers are amazed that the symbiosis goes as far as mechanically ejecting the algae when the environment does not provide the necessary conditions for the relation to continue.
However, the algae will return to their homes once the temperatures go down again to their normal level. This will not happen if the water does not cool off, in which case the bleached coral will die.
Even if the process is reversible, the scientists worry that the global warming trend, which is irreversible, will permanently damage the coral reefs.
Over the last years, the annual number of bleaching events increased. The prediction models assumed this would happen several decades in the future. Therefore, the scientists are alarmed that the process is going on now.
As to how conservationists deal with coral bleaching, the short-term solution had proven to be useful. They control the fish population, the nutrient quantity and the algae overgrowth, which in turn prove to be helpful in keeping the corals safe.
Image Source: Wikipedia