World Mangrove Day 2023 | Why mangroves are critical to India achieving its blue-green goals

Sundarbans is home to the Bengal tiger, and many other species of mammals, birds, amphibians, fish and reptiles. (Photo credit: David_Raju via Wikimedia Commons)

Shashank Ray’s first encounter with the fishing cat, an elusive inhabitant of wetland habitats, was in the Sundarbans as a teenager. “I was fascinated by the animal and then by its mangrove forest home. I later learnt that close to 453 fauna and 24 mangrove species can be found there. It also acts as a buffer against cyclones, protecting Kolkata from storms that originate in the Bay of Bengal,” he says. It prompted Ray to start eco-walks in the area, to acquaint others with its beauty.

But Ray knows this vibrant ecosystem is under threat. In 2011, the very dense mangrove cover at the Sundarbans was 1,038 square kilometres. A decade later, it was 994 square kilometres, according to the India State of Forest Report 2021. Experts believe that rising salinity levels are affecting this vital wetland. The delta was also hit by two severe cyclones – Amphan in 2020 and Yaas in 2021 – which took a toll on the vegetation.

It’s not just the Sunderbans. According to the United Nations Framework Convention on Climate Change, more than half of the mangroves in the Philippines have been lost since 1918. Africa saw a net loss of 984 square kilometres between 1975 and 2013, with 50 percent of it happening in Nigeria. In India, a 2022 study by the Birbal Sahni Institute of Palaeosciences suggested that by 2070, mangroves will reduce and shift by around 50 percent, especially in the southern parts, due to a decline in suitable habitats along the east and west coasts.

“Mangroves outside reserve forests, sanctuaries and national parks in India are under threat as they do not have legal protections. But mangroves, in general, are also facing the consequences of reduction in freshwater flow due to the damming of rivers. They are affected by increase in temperature and rising sea levels. These impacts are particularly high in the estuaries like the Cauvery where the rainfall is also less,” says Dr R. Ramasubramanian, senior fellow - coastal systems research, MS Swaminathan Research Foundation.

Also read: 2022 International Day for the Conservation of the Mangrove Ecosystem: Why mangroves are better than sea walls

Taking root

Mangroves are found in tropical and subtropical areas, i.e., between 25°N and 25°S latitude. There are 24-29 families and around 70 species in the world. India is home to about 3 percent of the total mangrove cover in South Asia, with the Sundarbans in West Bengal and Bhitarkanika mangroves in Odisha being the richest in diversity.

They provide a host of ecosystem services. The Sundarbans, for example, is home to a wide variety of fauna, including the Bengal tiger, fishing cat, mangrove snakes, goliath heron, saltwater crocodile and water monitor lizard. It is one of the most biodiverse mangrove forests in the world. Similarly, the Thane Creek in Maharashtra attracts migratory birds – the greater flamingos and lesser flamingos. Between December 2021 and March 2022, 54,000 greater flamingos were spotted at the Thane Creek Flamingo Sanctuary.

Mangroves dispense a wide range of benefits to humans too. They protect coastal areas from tidal surges, help with oil and plastic pollution control, and provide timber and fuelwood. Another vital benefit is their ability to sequester carbon dioxide from the air. “As blue carbon sinks, mangroves can typically store a high amount of carbon – up to 4 times more than rainforests. For our large coastal cities, this property is instrumental in mitigating the urban heat island effect. An example of this is the Vikhroli mangroves in Mumbai, which sequester close to 60,000 tonnes of CO2 every year,” says Tejashree Joshi, head - environmental sustainability, Godrej & Boyce, which manages the mangroves.

They are also highly suitable feeding grounds for fish. The major resources found in these waters are detritivore species of fish, crabs, crustaceans, and mollusks. Roughly about 60 percent of India’s coastal marine fish species are dependent on the mangrove ecosystem. So, these wetlands provide livelihood to a large number of small-scale artisanal fishermen.

Cumulatively, the benefits are significant. A 2012 study found that the Pichavaram mangroves in Tamil Nadu were worth Rs 353.52 crore annually. Fisheries and ecotourism contributed Rs 1.66 crore and Rs 15.75 crore, respectively. Its indirect use value (storm protection, water purification, and carbon storage) was estimated at Rs 336.11 crore, while its non-use value (knowledge that the mangroves exist, even if they are not used directly) was estimated to be worth Rs 1,05,185.

Cause for concern

Yet, mangroves the world over are in danger of extinction. According to the IUCN red list, 11 of the 70 mangrove species in the world (16 percent) are at an elevated threat of extinction. Among them, two species, namely Sonneratia griffithii (critically endangered) and Heritiera fomes (endangered), are found in India.

The biggest threats to mangroves in the country include:

●     Grazing and fodder collection for cattle

●     Conversion of mangrove wetlands for aquaculture/ agriculture/ industries

●     Changes in topography, bar mouth closure or reduction in fresh water flow

●     Climate change – cyclones, higher evapotranspiration, increase in salinity

●     Oil and plastic pollution

●     Felling for domestic needs

It’s not all doom and gloom though. India's mangrove cover increased by 17 sq km between 2019 and 2021, as per the India State of Forest Report 2021. This has been attributed to their restoration and natural regeneration, reduction in dependency for domestic needs such as fodder and grazing, and awareness being created among communities about their benefits.

For instance, Godrej & Boyce has made available a Mangroves app in 13 languages, including English, Hindi, French, Spanish, and nine languages spoken across India’s coastal states. “It offers a visual taxonomy of 67 species, identification guides, species descriptions, and information about mangrove distribution, ecosystem, threats, and conservation measures,” says Joshi. The MS Swaminathan Research Foundation, this year, launched a book, Biodiversity and Importance of Mangrove Ecosystem, that provides a comprehensive overview of the mangrove ecosystem in the country.

However, more funding and active participation from all stakeholders is needed to further protect mangroves. New plantations will be needed where damage to ecosystems is extensive, while rehabilitation will be the focus where sparse mangroves can become dense forests.

To this end, a new mission was announced earlier this year by the government of India to preserve and conserve mangroves. The Mangrove Initiative for Shoreline Habitats and Tangible Incomes (MISHTI) will plant mangroves along the country’s coastline and salt pan lands. India is also a participant in the Mangrove Alliance for Climate (MAC). Led by the United Arab Emirates and Indonesia, MAC’s goals include educating people about the role of mangroves in curbing global warming and sharing expertise in researching, managing, and protecting coastal areas.

“The general public too can take up plantations jointly with the state forest departments and other agencies. They can influence the policymakers to safeguard mangroves outside protected areas. Only by working together can we guarantee their future, and ours, in turn,” says Dr R. Ramasubramanian.