Sungmoon Chung - Jeju
Coral reefs are the most conservative sources in marine ecosystems, helping to have the highest biodiversity under the ocean. It acts to perform various functions: subsisting food, protecting from flooding, and sustaining the fishing. However, due to the climate change of
rising temperatures and higher carbon emissions, more coral reefs are bleaching white, indicating the death of its habitats. The loss of coral reefs is a severe problem in aquaculture unless the greenhouse gases are stabilized, coral reefs need to endure their strengths
by adapting and reacting against their different conditions:
Global warming is one of the biggest threats to the marine environment. The temperature of the planet is rising continuously because the amount of carbon emissions that are exposed to industrial factories is increasing. When the temperature abruptly changes, corals are observed to expel the symbiotic algae living in their tissues, which are responsible for their colour. Its scientific name is ‘symbiodinium’, which is a microscopic algae that harvests light and produces chemical energy in the form of carbon-rich compounds. Just a small change in ocean temperatures (1-2°C) that is sustained over several weeks can lead to coral bleaching or turning corals white. If this continues over time, corals eventually die.
The recent study projected from the California State Universitiesper cent shows that coral reefs, through genetic adaptations, could reduce the rate of bleaching from 20 to 80 percent of levels expected by the year 2100 if there are large reductions in carbon dioxide emissions.
The other research from the University of Miami (UM) observed the sensitivity of two types of corals found in Florida and the Caribbean waters. Their adaptations were tested under the
circumstances of high temperatures and acidity conditions.
The researchers placed a staghorn coral (Acropora cervicornis) and the other mountainous star coral (Orbicella faveolata) to be exposed under elevated temperatures of 32°C and increased carbon dioxide levels for nine weeks. By the end of the nine weeks, corals that were still surviving were recovered at the cool temperature and normal pH to determine its capacity. As a result, the staghorn coral was more sensitive to heata . It experienced 100% mortality after 25 days at the elevated temperature of 1.5°C above the mean temperature in Florida waters. On the other side, the mountainous star coral survived 62 days in the same condition. So, how did the mountainous star coral endure much longer than the staghorn coral? It had special type of algae, called ‘D symbionts’ that allowed the coral cells to be adapted more suitably. This is also known as the ‘Clade D Symbiodinium’, and it’s thermally
tolerant coral endosymbionts that confer resistance to elevated sea surface temperature and bleaching to the host.
As the researches are showing, corals are very sensitive to a lot of various factors such as temperature, pH etc. It is very important for corals to have an appropriate water temperature. There are corals called cool-water corals that can adapt to a slightly warmer ocean. The study found that some corals in the normally cool waters of the Cook Islands carry genetic variants that predispose them to heat tolerance. In this work, the scientists identified genes that make some individual corals more heat tolerant than others. They ran
computer simulations if coral could survive both in mild and moderate, and severe scenarios. Corals were able to survive in moderate temperature, but, in severe cases, it became even more clear that their future extinction due to climate change became much clearer. Over the past few years, coral reefs have experienced the worst bleaching and mortality events in
the recorded history of the marine environment. Life on earth is becoming harder due to warmer water and unsafe habitats. The earth is not only for human beings, but all of the living things on the planet. It is our greatest responsibility of the millennium to preserve nature.
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