Coral Bleaching

What are Corals?

Coral reefs are the rainforests of the underwater made up of polyps (genetically identical organisms). These polyps consist of microscopic algae called zooxanthellae which live in their tissues. The coral helps zooxanthellae with the compounds necessary for photosynthesis. In return, the zooxanthellae provide essential nutrients to the corals. Zooxanthellae algae are responsible for the beautiful and unique colors of corals. Stony corals, shallow-water corals, soft corals, and deep-water corals are some of the different types of corals.

What is Coral Bleaching?

When corals face stress by changes in environmental conditions such as water temperature, pH value, light, and nutrients, they expel the symbiotic algae zooxanthellae living in their tissues, causing corals to turn completely white. This phenomenon is called coral bleaching.

The corals do not die immediately after the expulsion of symbiotic algae. The bleached corals can regain the zooxanthellae if the environment improves and can slowly recover. The corals will gradually weaken and die if they remain bleached for a long time.

What are the Causes of Coral Bleaching?

Rise in Sea Temperature: the optimal water temperature range for coral growth is 20-28°C, a slight increase in ocean temperature can harm corals.

  1. Ocean Acidification: Due to the greenhouse effect and rise of carbon dioxide levels, oceans absorb more carbon dioxide leading to the weakened coral's absorption of calcium carbonate capacity, which is essential for their survival.
  2. Increased sedimentation will reduce light availability (turbidity), leading to reduced coral photosynthesis and growth.
  3. The growth of phytoplankton due to increased nutrient concentrations affects the coral's health.
  4. The changes in tropical weather patterns result in less cloud cover and more radiations which induce coral bleaching.
  5. Agricultural pesticides, industrial and household wastewater discharged into the sea cause harmful impacts on coral reefs.
  6. The chemicals present in sunscreen products such as Benzophenone and Octyl methoxycinnamate disrupt corals' reproduction and growth cycles.

What are the Effects of Coral Bleaching?

  1. The decline in collar reefs will result in loss of habitat for numerous plant and animal species that depend on them.
  2. Bleaching and degradation of corals will affect the local economy as it does not attract divers and other tourists.
  3. The decline in coral reefs may result in increased storm damage, erosion, and flooding.

How to Prevent Coral Bleaching?

  1. Use sustainable energy to slow down global warming.
  2. Terminate unnecessary coastal development.
  3. Minimize the use of chemically enhanced fertilizers, insecticides, pesticides, and herbicides that are non-degradable.
  4. Treating industrial waste before disposing it into water bodies.
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