Meera Bhardwaj:
There has been a considerable loss of mangrove forests in the Andaman Islands, India. Green Minute takes a look at this unique ecosystem in Andaman Islands as we are celebrating the International Mangrove Conservation Day on July 26 to raise awareness about the importance of mangrove ecosystem and promote sustainable solutions to make for their losses.
This has been due to tidal flooding and the severe impact of 2004 tsunami triggered by 9.1-9.3 magnitude earthquake in the northern Sumatra Island of Indonesia. Apart from this, in the past two decades, mangroves have made way for agricultural activities, tourism development and heavy logging in some areas of south, middle and north Andaman Islands.
In the aftermath of the 2004 tsunami, the Andaman & Nicobar Islands suffered not only upliftment of land mass and subsidence with some areas experiencing an uplift of three meters. In view of this, the north and middle Andaman Islands (being closer to the epicenter) was impacted the most with the western coast experiencing the emergence of coastlines. Some low-lying areas in the capital city of Sri Vijaya Puram (Port Blair) led to permanent submergence of mangroves due to the 2004 tsunami.
BIODIVERSITY HOTSPOT
In fact, Andaman Islands are considered a biodiversity hotspot due to the abundance of floral and faunal species. However, according to researchers, mangroves in these islands are vulnerable due to natural disasters like storms, cyclones, tsunamis and earthquakes. “There is an urgent need to identify vulnerable mangrove zones and plan strategies for mitigating and protecting the delicate mangrove ecosystem,” says a local eco-activist.
Rapid infrastructural development has spelt doom for mangrove cover in Middle and North Andaman which are being explored for linear structures and expansion of tourism development and new destination spots. Further, mangrove cover has already been decimated in south Andaman with Sri Vijaya Puram (Port Blair) taking the brunt of developmental activities like land development, aquaculture, etc while north Andaman is witnessing highway and hospitality development.
SUBMERGENCE & FLOODING
In fact, even as this reporter travelled from Sri Vijaya Puram (Port Blair) to Wandoor Bay, a few areas (which our guide indicated) have been submerged and are still flooded. New water bodies have been created amidst urban structures and they are now home to waders and other water birds. Further, due to tidal flooding in south Andaman Islands, the landmass has been uplifted while in the north Andaman area, dead coral reefs can be seen at many coastal lines.
According to studies done by Shivshankar and others, more than 1100 hectares of mangrove forests were lost due to tsunami and these areas are completely flooded. However, studies have revealed that some mangroves like Rhizophora apiculate, Avicennia marina, and other species have started making a new home in these flooded areas.
MOVEMENT OF MANGROVES
With land sinking in many small islands, mangroves are moving towards land away from the sea. But mangrove recovery has been happening in private lands and therefore, caused a lot of manmade problems. In these private lands, people are trying to recover and fill these lands for building construction purposes be it residential or commercial.
But in South Andaman, Sri Vijaya Puram (Port Blair) being the capital city and hub for all tourism activities – there has been a flurry of new hotels and resorts, and so, mangroves are being pushed towards the sea. A farmer said, “We too are having a tough time as fields have become salty while for the fishing community, fishes, crabs and other marine animals are becoming scarce.”
STEEP MANGROVE DECLINE
On the west coast, there has been a steep mangrove decline of 90 percent due to steep land rise while on the east coast, mangrove cover has declined by 40-70 percent.
For people living in North Andaman Island, conditions are pretty bad due to the high loss in mangrove cover. The vulnerability of the coastline and mangroves has also been linked to the altering ground surface.
NEW RESEARCH STUDIES
As part of SWAMP (Sustainable Wetlands Adaptable Mitigation Program), a research paper was published in Geoscience Frontiers by Biswajit Mondal, Rupesh K Bhomia, Ashis Kumar Saha, and Richard K Mac Kenzie in 2024. Their study focused on Andaman Islands which has a geographical area of 6408 square kilometers and an approximate coastline (including Nicobar Islands) of 1962 square kilometers.
The purpose of the study was also to examine the vulnerability scenario in relation to the 2004 earthquake. As a result of the earthquake, Andaman Island experienced upliftment (northern part), and subsidence (southern part) and central portion with limited or no change.
MANGROVE COVER OF ANDAMAN
Total mangrove cover: 616.45 sq km
Very dense mangrove: 398.73 sq km
Moderately dense: 168.34 sq km
Open Mangrove: 49.38 sq km
DISTINCT MANGROVE SPECIES
The Andaman Islands are home to 38 distinct mangrove species, which is more than half of the total number of real mangrove species found across the world.
The researchers selected study sites that were surrounded by dense mangrove forests, with most species found on the seaward sides of creeks. Common genera found in Andaman includes – Avicennia, Bruguiera, Ceriops, Excoecaria, Lumnitzera, Rhizophora and Xylocarpus.
HIGH VULNERABILITY OF COASTLINE
The study by Mondal and others employed multiple parameters, including physical and human factors, and was conducted in South Andaman Island.
The data revealed that 30.3 percent of the coastline is highly vulnerable and 9.2 percent is extremely vulnerable. This study, therefore, strongly supports their conclusion that the regions are vulnerable. The study is also distinctive in that it has covered the entire Andaman Islands, which can serve as a valuable guide for planners, and it has also addressed the vulnerability of mangroves, which was absent from previous studies.
RISE IN SEA LEVEL
Further, this study demonstrated that the sea level is rising in the region, and as a result of subsidence, the vulnerability of subsided zones such as Zone 5 is also considerable.
According to Veettil etal’s research, the South and Middle Andaman Islands’ mangrove forests are especially susceptible to sea level rise and tsunamis due to their comparatively low elevation compared to the northern part.
ALTERATION IN MANGROVE HABITAT
However, mangroves face another issue because land elevation has altered the mangrove habitat, causing mangrove trees to be replaced by terrestrial vegetation to become more abundant in this distinctive ecosystem.
In conclusion, this study examined multiple dynamic parameters to assess coastal and mangrove vulnerability along six mangrove zones of Andaman Islands. On an average, around 34 percent of coastal grids and over 23 percent of mangrove grids along the zones are at high to extremely high risk.
HIGH THREAT TO COASTAL LANDS
The coastal lands, especially Zone 1 (Diglipur and surroundings), 3 (Kalara and Parangara Creek surroundings), 4 (Yol Jig River surroundings), and 5 (Shoal Bay region), are under severe threat in terms of coastal vulnerability.
In terms of mangrove vulnerability, Zone 5 is also more vulnerable than the other zones, which also shows that mangroves in subsided regions are relatively more vulnerable than those that have been raised.
Now, it is high time for planners and the central government to take action and protect the remaining mangrove cover in Andaman Island and take concrete steps for expansion of this unique ecosystem that protects coastlines and provides many ecological and economic benefits.
(PHOTO CREDIT: ALL PHOTOS BY MEERA BHARDWAJ AT SOUTH, MIDDLE & NORTH ANDAMAN ISLANDS)