INVC NEWSNew Delhi,
Andaman and Nicobar Islands of India are the hot-spots of biodiversity with their unique Coral Reef bio-reserve. In recent decades, they have been under constant threat due to global warming and sea level rise. Coral reef biodiversity at Andaman region, roughly around 11,000 sq.km., was seriously affected during the 2004 Tsunami event and also are undergoing the stress from the increasing sea surface temperature.
Currently, there is no mechanism other than Scuba diving to examine the corals and assess the extent of damage or rejuvenation that might be taking place since the great damages happened earlier. National Institute of Ocean Technology (NIOT), for the first time, used the indigenously-developed Remotely Operated Vehicle (PROVe), to map the coral reefs in Andaman & Nicobar Islands (North Bay and Chidiyatapu) and that the ROV can be used for this purpose efficiently.
The ROV can effectively map 4-6 sq.km. of coral reefs in a day, whereas the same job takes about a week for a Scuba diver. The images of corals recorded by the ROV are useful to study the biodiversity of coral reefs and their evolution. The underwater visuals have shown the coral debris and boulders caused by the 2004 Tsunami, at the same time, also capturing some locations where the rejuvenation of the colonies of branching corals, stony coral, brain corals was observed. The water temperature ranged between 31oC at surface and 30.5oC at 1 m water depth. It further decreases in deeper waters as recorded by the ROV based sensor.
The radiometer attached on the ROV provided the spectral signatures of different types of corals in Andaman. The spectral signatures of the corals are valuable in developing algorithms to map the coral reefs using sensing techniques, especially the satellite remote sensing. A good news is that there are no evidences of coral bleaching at Andaman reef during the mapping period in April 2016 but will require constant monitoring to know what would happen when the temperature raises further.
