New coral species discovered from Andaman and Nicobar Islands in India

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Ctenactis triangularis from Andaman and Nicobar Islands
Image Credit: C Raghunathan

Shedding light to the rich but unexplored marine biodiversity of India, Scientists of the Zoological Survey of India described a new species of coral reef, Ctenactis triangularis from Andaman and Nicobar Islands of India. The new species which belongs to the family of mushroom corals, adds a fourth member to the Ctenactis genus of corals.

“The first specimen of the species was collected from Rutland Island from South Andaman by snorkeling and skin-diving", said the scientists. Later another specimen of the same coral was observed at the North Bay in South Andaman in December 2008. Researchers were able to spot the same species again after two years, in 2010, off the coast of Elephant Beach in Havelock Island.

Tamal Mondal and C. Raghunathan , scientists at the Andaman and Nicobar Regional Centre of Zoological Survey of India situated at Port Blair have reported and described the identity of the new species.

Distinguishing features of Ctenactis triangularis

According to the ZSI scientists, the newly described species has characteristics which make it different from all the three members of the genus previously reported by other studies.

Ctenactis triangularis
Image Courtesy: JOTT

The discovery which is published in the Journal of Threatened Taxa reveals that three characteristics make the new species different from its closest relatives.

The major feature is the triangular, flat shaped skeleton or corallum which makes it different. According t the study, ‘divisible mouth fossa, spinulose costal spines and cylindrical septal teeth’ also make it distinguished from other members of its genus.

To underscore one of its most visible distinguishing features – its flat triangular skeleton, the scientists have named it as triangularis. “The species has been named after the triangle-shaped arm like coralla, which gives a unique morphological character to distinguish it from other related species”, says the study.

Conservation Status of Ctenactis triangularis

Despite the new discovery, the future of the coral reefs off the coast of Andaman and Nicobar are likely bleaker, points out the study. “Threats, which can be categorized as natural and anthropogenic, to the reef biodiversity, have been encountered for a long time.”, it says.

According to the researchers, the new species belong to Scleractinian corals which are protected under CITES Appendix II which curbs the transnational smuggling of these corals. Moreover, they are also included in the Schedule I of protected organisms of Indian Wildlife Act, 1972. 

One third of the coral reefs in the world will suffer degradation by 2030 due to climate change

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According to a new study on climate change and its effects,  a group of scientists have found that the chances of saving world’s coral reef population from the ill effects of climate change is thinning day by day as the greenhouse emissions are increasing.

Great Barrier Reef
Image courtesy:  Richard Ling

The danger to coral reefs is almost impossible to be averted, indicates the study which is published in the journal Nature Climate Change. One third of the coral reefs in the world will suffer long term degradation due to climate change by 2030, finds the study even though the estimation is based on the most optimistic IPCC estimations on emissions.

“One-third (9–60%, 68% uncertainty range) of the world’s coral reefs are projected to be subject to long-term degradation under the most optimistic new IPCC emissions scenario, RCP3-PD.”, says the study

"The window of opportunity to preserve the majority of coral reefs, part of the world's natural heritage, is small," said Malte Meinshausen, a co-author of the paper to Reuters news agency. This will happen even if the emission cuts are made stricter, shows the study.

Bleaching and decalcification of corals

The scientists have assessed the impact of emissions on 2160 coral reefs in different parts of the globe, with the help of climate models. The study points out that the emission of Carbon dioxide, a greenhouse gas, has increased by more than 3 percent last year. As a result, the average temperature of the globe has also increased by 0.8 degree Celsius approximately, during the last century.

The increasing global temperature and warmer oceans will bleach the corals to death. Thus, the reefs turn pale when the warm sea surface triggers mass bleaching events across the globe, says the study.

Even if the corals survive the ill effects of bleaching, it is difficult for them to survive a prolonged period of heating up of the ocean. According to the study, when the oceans stayed hot for a prolonged period during 1998, 16 percent of corals vanished from the face of earth.

Acidification is more fatal to the survival of corals than the bleaching events. Acidification of ocean is directly proportional to the presence of Carbon dioxide in the ocean surface. With the acidification increasing, the rate of calcification - a process which is crucial to the existence of corals - gets disrupted, leaving them to corrode to death.

Location of Corals in the world

2 degree Celsius limit is no safer zone for corals

The study also points out that the present notions of safe emission levels and safe temperature rise levels may not save coral reefs. 2 degree Celsius is widely considered as a safe emission limit to avoid the devastating effects like droughts, sea level rise or failure of cultivation. However, it will not help corals to avoid the serious threats of global warming, shows the study.

According to the scientists, the chances of survival for at least half of the coral reefs in the world will remain live only if the average mean temperature rise stay below 1.2 degrees compared to that of pre-industrial period.  

Though the reefs’ ability to adapt and evolve with changing quality of the habitat may make a difference in their survival to the acidification and bleaching events. However, their ability to adapt significantly within a matter of decades (which is a very small period for evolutionary processes), in an atmosphere of continuously changing ocean temperatures is still uncertain.

Moreover, the rate and magnitude of warming, which the globe is going to face, has no equals in the past, points out the scientists. They are doubtless that the prominence of coral reefs in coastal ecosystems will plummet, if the global mean temperatures exceed 2 degree Celsius above that of the pre-industrial era.