Nicobars lost 97 % of mangrove cover in 2004 tsunami, reveals new study

Report by: 
EOI BUREAU
Port Blair
29 Aug 2018

A recent study by researchers of Wildlife Institute of India and Salim Ali Centre for Ornithology and Natural History (SACON) has revealed that the mangrove cover in the Nicobar region bore the brunt of the Sumatra-Andaman earthquake followed by the catastrophic tsunami in 2004. Superseding earlier findings, the latest study found that 97 percent of the mangrove cover in Nicobar was razed during the natural disaster. “The study assessed the impact of the large-scale natural disturbance on the mangrove habitats of Nicobar Island and studied the initial patterns of mangrove succession. Surviving mangrove patches were observed at only three sites for the entire Nicobar Islands and the estimated mangrove cover loss was found to be 97%. However, the natural disturbance triggered the emergence of potential habitats for regrowing mangroves and uncovered hitherto unrecorded mangrove species in the Nicobar islands,” as per the lead author of the study.
“We found the presence of 20 mangrove species in the Nicobar Islands, which includes new distributional records and local extinctions after the major natural disturbance. The landward mangroves seem to be more vulnerable to such disturbances. The initial community structure of the successional mangroves is dominated by Rhizophora mucronata and Bruguiera gymnorhiza with a cumulative abundance of 70%. The community structure that included 3182 individual mangroves at the successional habitats showed a significant difference (P = 0.034) among the three islands groups (viz. Northern, Central and Southern) in the Nicobar Islands. Habitat and species loss are inevitable with the high intensity of tsunami and subsidence. But facilitating the mangrove regrowth at the potential habitats may be vital to restoring the functionality of the coastal system and the livelihood of local communities. The outcome of the study is critical for forest managers to regrow mangroves in the Nicobar Islands,” as per the researchers, who also suggested long-term monitoring of the sites to understand the overall long-term impacts of tsunami and subsidence on the mangrove habitats of Nicobars.

HIGHLIGHTS

•         Tsunami and tectonic plate subduction caused major damage to mangroves.

•         Local extinction and addition of mangrove species observed.

•         Mangrove succession at erstwhile terrestrial habitats.

•         Mangrove community structure varied among the island groups.