The impacts of climate change on the Coral Reef and Reef biodiversity of the St. Martin Island under rapid climate change.

Coral reefs have a great ecological and economic importance to the world. Coral reefs contain a unique biodiversity. Globally coral providing shelter to almost 25% marine species. The climate is changing and there are a great impacts of climate change on the marine ecosystem. Climate change is altering life in the ocean, transforming ecosystems and the services they provide. Under marine salty ecosystem the corals have a different biodiversity, besides the corals are very much vulnerable to the sea temperature rising, ocean acidification etc. Under the continuous stress of climate variables the reefs are destroying and the biodiversity holding it are under great threat. Due to the climate change and uncontrolled tourism the St. Martin Island is under great threat.

St. Martin’s Island locally called ‘Narikel Jinjira’ is located on the southern-most part of Bangladesh, roughly between 20°341- 20°391 N and 92°181 – 92°211 E. The island is located in the Northeastern part of Bay of Bengal and while being within the tropical belt; its weather is heavily influenced by the subtropical monsoon climate that prevails over Bangladesh.

The St. Martin Island is the only coral island of Bangladesh and is great attraction for the tourist of Bangladesh. This island has also a great ecosystem value. There are 234 species of fishes in St. Martin Island of which 98 species are coral associated. There are 187 species of mollusc and 7 crab species. A total 66 coral species are recorded, of which 19 are fossil corals, 36 living corals and the rest are under 6 families of subclass Octocorallia. A total 14 species of algae have been recorded from St. Martin Island (Hossain, 2006).

The temperature of the upper few meter of the ocean has increased by approximately 0.130 C per decade over last 100 years (Anon., 2019). The global temperature increase is also changing the ocean chemistry and is putting a great threat to the coral reef ecosystem. The threats are caused by warmer atmospheric temperature and increasing levels of CO2 in seawater. As the temperature of the atmosphere is increasing the temperature of the sea also rising. This warming causes corals to lose the microscopic algae that produce food that corals need, placing stress on the corals. Without this algae coral also lose their coloration, a condition known as coral bleaching, because the loss of algae reveals the white color of the calcium carbonate structure underlying the polyps. Severe or prolonged bleaching can kill coral colonies or leave them more vulnerable to other threats such as infectious disease.
Ocean acidification refers to the decrease of ocean PH. Before the industrial revolution, the atmosphere contained about 280 parts per million (ppm) of CO2; today it is 35% higher (>380 ppm) and the increase in CO2 continues to accelerate faster than predicted. In general the concentration of CO2 in atmosphere is equilibrium to the concentration present in the ocean. CO2 entering to the ocean as “Carbonic Acid”. As the CO2 is also rising the ocean PH also decreasing which putting the coral reef and the reef biodiversity under great threat.
Changes in the storm pattern leads to stronger and frequent storms that can cause the destruction of the coral colony. Change in the precipitation pattern increase freshwater runoff, sedimentation and introduce more pollutant to the marine water that impact on the coral reef formation.
When conditions such as the temperature change or the change in the ocean PH, corals expels their symbiotic algae living in their tissue and the corals die. Under this circumstances the biodiversity of the St. Martin Island under great threat. If the corals of the Island completely destroyed the coral associated species will lost their habitat and will eventually extinct.
What if all the coral reef of St. Martin Island disappeared?
• Many marine organism will lost their food and habitat.
• Coral associated organism will extinct.
• The island will lost its beauty.
• The complete ecosystem will be disrupted.
A recent survey shows that about 67% corals of the St. Martin Island has been destroyed and rest will be damaged due to the climate change and manmade causes. As we saw above the island is a great reservoir of marine biodiversity so it’s our great responsibility to take immediate actions to save the coral. Climate mitigation action should be taken immediately to limit the long term impacts. Besides providing habitat for marine organisms and its natural beauty many corals are known as the source of life saving medicine for virus and bacteria related diseases, cancer, arthritis and other diseases. The government as well as the public should be more aware to conserve this unique marine ecosystem.
Ways to save the corals of the St. Martin Island-
• Reducing the Global Greenhouse Gas (GHG) emissions.
• More controlled tourism in the island.
• Increased investment in research sector.
• Stop illegal extraction of coral.
• Proper enforcement of Environmental law and regulation.
• Stop illegal fishing.
• Enforcement of Eco-tourism.
References
Anon., 2019. National Ocean Service. [Online]
Available at: http://oceanservice.noaa.gov/facts/coralreef-climate.html
Hossain, M.M. and Islam, M.H., 2006. Status of the biodiversity of St. Martin’s Island, Bay of Bengal, Bangladesh. Pakistan Journal of Marine Sciences, 15(2), pp.201-210.

Ashim Chandra Das
Student (Final Year)
Environmental Science and Disaster Management
Noakhali Science and Technology University

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