Declining Mangrove Cover: NASA STUDY

NASA recently brought attention to the disappearance of mangroves on Katchal Island, which is a part of India's Nicobar archipelago.

Image Source - NASA.gov

Findings Of NASA

Mangrove loss:

• The study revealed how much of the world's mangroves have disappeared during the last two decades.
• On August 8, 2022, the NASA Earth Observatory displayed a satellite-shot map of the island. The mapping highlighted the tidal wetland loss from 1999 to 2019.

Earthquake impact

• The Andaman earthquake in December 2004 had a significant impact on the islands, causing up to 3 meters (10 feet) of land to collapse.
• As a result of this, numerous mangrove habitats were drowned, and in other places, the extent of mangroves was reduced by more than 90%.

Tidal marshes:

• Between 1999 and 2019, 4,000 square kilometres of tidal wetlands were gone.
• Among the three types of tidal wetlands, mangroves showed the highest ratio of loss to gain. The other two were marshes and tidal flats.
• Between 1999 and 2019, mangroves are thought to have lost 3,700 square kilometres.
• Globally, tidal wetlands are declining, yet increases of 2,100 square kilometres and losses of 2,300 square kilometres show how dynamic these systems are.
• Tidal wetlands in Africa had the highest loss-to-gain ratio outside of Asia. The countries that suffered the most were Guinea-Bissau, Mozambique, and Nigeria.

Causes of wetland change:

• Anthropogenic activities
• Sea level rise,
• Shoreline erosion,
• Storms,
• Altered sediment flow and
• Subsidence.

About Mangroves

• A mangrove is a tiny tree or shrub that grows along coasts and establishes itself in saline sediments, frequently beneath the water.
• The family Rhizophoraceae, Acanthaceae, Lythraceae, Combretaceae, and Arecaceae all contain flowering trees, including mangroves.
• A mangrove tree's bottom trunk and its extensive root system are partially submerged in the sea, but its upper trunk, along with its branches and foliage, is entirely above the waterline.
• Many species (like banyan trees) have roots that diverge from stems and branches and penetrate the soil at a distance from the main stem.

Features:

Can Sustain Environment with Salt:

• Mangroves are unique in that they can endure extremely unfavourable conditions, such as high salinity and low oxygen levels.

• Mangrove trees have intricate salt filtering systems and intricate root systems to withstand exposure to saltwater and wave action.
• In the saline and brackish water they live in, the roots filter out 90% of the salt that comes into touch with them. Mangrove species that have glands in their leaves can exude salt.

Low oxygen:

• For respiration, any plant's underground tissue needs oxygen. But in a mangrove environment, there is little to no oxygen in the soil.
• As a result, the mangrove root system takes in oxygen from the surrounding air.
• Mangroves develop unique roots termed pneumatophores, or breathing roots, for this purpose.
• The underground tissues of these roots can receive oxygen because of their many apertures.
• Mangroves, like plants in the desert, store fresh water in their large, succulent leaves. The leaves' waxy layer seals in the water and reduces evaporation.

Mangroves are viviparous:

• Their seeds germinate while still attached to the parent tree. Once germinated, the seedling grows into a propagule.
• The mature propagule then drops into the water and gets transported to a different spot, eventually taking root in a solid ground

Distribution of Mangroves

• The tropical and subtropical regions of the world include more than 118 nations and territories where mangroves can be found.
• The region with the most mangroves is Asia, which is followed by Africa, North and Central America, Oceania, and South America. Only 15 countries contain almost 75% of the world's mangrove forests.

In India

• Mangrove forests in India can be found in the deltas of the Ganges, Mahanadi, Krishna, Godavari, and Cauvery rivers.
• Kerala's backwaters are covered in a dense mangrove forest.
• The largest mangrove area in the world and a UNESCO World Heritage Site is the Sundarbans in West Bengal. It stretches from Bangladesh's Baleswar River to West Bengal's Hooghly River.
• The second-largest mangrove forest in India is located in Odisha, in the Bhitarkanika mangrove system.
• Mangrove trees cover a huge area of water in Pichavaram, Tamil Nadu. Numerous aquatic bird species call it home.

Importance of Mangroves

Acts as shield

• Mangrove forests provide a natural barrier against sea-level rise, coastal flooding, and storm surge.
• Their complex root system helps to stabilize the beach and lessen coastal erosion caused by storm surges. They act as speed-breakers to slow the tides along with the tree trunks.

Filters Water:

• Mangrove thickets protect the quality of the water by filtering contaminants and capturing sediments that come from the land.

Habitation:

• They serve as a habitat provider for a wide variety of terrestrial organisms.
• Lizards, snakes, and bird nests can all find shelter in their branches. Mangroves serve as the sole breeding, spawning, and hatching grounds for numerous species of fish and shellfish that are found in coastal and offshore waters.

Climate Change

• Mangroves are also climate change powerhouses. When it comes to carbon storage, mangroves are formidable forces.
• Studies show that mangroves can store more carbon in the peat soil beneath than other types of trees. They keep this carbon in storage for ages.

Sources of Income:

• The mangroves are a major source of income for many people who live in and around them.
• The trees provide wood for building and burning.
• Local fishermen may catch a variety of fish, crabs, and shellfish thanks to the ecology. Also supported by the ecology is tourism.

Major Threats

• Mangroves are most at risk from coastal development, which includes erecting shrimp farms, hotels, and other buildings.
• To make place for agricultural land and habitations, mangrove forests are destroyed.
• Mangrove trees are used for animal fodder, charcoal production, firewood, and construction materials. Overharvesting has occurred in several regions of the world, which is no longer sustainable.
• Other dangers to mangrove ecosystems include overfishing, pollution, and increasing sea levels.
• At least one-third of all mangrove forests, according to scientists, have vanished in recent years.

Way forward

The coastal environment depends critically on the mangroves for their survival and preservation.

Proper planting drives must be made in order to make up for the plants that are harmed as a result of various anthropogenic and natural activities.

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