There are hardly any mangroves left in Kerala, but now there is a realisation that preserving what is left and regenerating more will help combat climate change by sequestering carbon and buffering the effects of sea level rise

For a state that has 44 rivers and a wide network of estuaries and backwaters with tidal action, Kerala has a relatively small area under mangroves – just 25 sq km at present, down from 700 sq km in 1957. The mangrove patches that still survive are distributed across many coastal districts.

The mangroves in Kerala are unique in the sense that more than half are under private ownership, making conservation difficult. Mangrove conservation faces a double whammy, since private owners are not motivated enough to hold on to the unique vegetation, as it does not provide a direct and immediate economic benefit. For the state government, administering patches over which they have not control is difficult.

So mangroves are being destroyed for agriculture, construction, development projects and shrimp aquaculture ponds. Projections indicate that there will be a further sharp decline in mangrove area in the near future, according a report by the Kerala State Biodiversity Board.

Mangroves have an important role in dealing with climate change. These evergreen close-canopy shrubs produce biomass and green leaves copiously all through their lives. In the process, they absorb atmospheric carbon in large quantities and help with sequestration. They also shed their leaves copiously, strengthening the nutrient cycle.

Living platforms

Stands of mangrove plants also protect the coast from the invading sea, both from storm surges and sea level rise. The roots of the plants trap the silt in the estuarine water and the falling leaves, creating a living platform, which grows faster than the rising sea, thereby protecting the coast.

This is of significance in Kerala, since the National Institute of Oceanography based in Goa estimates that Kerala’s coast is vulnerable to sea level rise of 1.75 mm per year.

Distribution of mangroves in Kerala. (Source: Kerala State Biodiversity Board)
Distribution of mangroves in Kerala. (Source: Kerala State Biodiversity Board)

The worst impact is projected to be around the estuarine network in and around the commercial city of Kochi, where good mangrove stands have been destroyed in recent decades for roads, bridges and a container terminal.

In the neighbourhood of Chettuva village of Thrissur district of central Kerala, a citizens’ group has been working for years to pressurise the state government to have the land around the estuaries surveyed so that mangroves standing on government lands can be identified and encroachments removed.

The group, Nature, Environment and Wildlife Society of India (NEWSI), considers this the first step towards conservation of the mangroves. Their efforts to identify water bodies and mangrove patches in government land is strengthening the promise for conservation of an ecosystem that can give livelihood benefits to thousands of families and provide increased climate resilience to the state.

According to Ravi Panakkal of NEWSI, their efforts has led to identification of a mangrove-encrusted, 8.5 acre island in the Chettuva river as government property. “Pictures of this island are now splashed across many government publicity materials,” he told indiaclimatedialogue.net

Natural barriers

The group of environment activists got interested in mangroves after the tsunami of December 2004. Though the central Kerala coastline was not affected by the tsunami, the magnitude of the event led them to think about the importance of conserving natural barriers for protection. “That was when we started studying the importance of mangroves,” said Sugathan K. of NEWSI.

Sugathan says that it is at the time they focussed on the mangrove-encrusted island, which was surrounded by other mangrove patches in private ownership. Since there were tourism-related activities underway in the neighbourhood, the group felt that they needed to check the ownership of this island in the Chettuva River in Orumaniyur village council area, and push for its conservation.

The group appealed to the then state forest minister for its survey and conservation, said Panakkal. Though there was a public statement by him that this would be done, there was no response after that. The group even held rallies outside the state secretariat in Thiruvananthapuram and the district collectorate in Thrissur in 2012.

Survey conducted

“As a result, a survey was conducted and the land was found to be that of the revenue department,” Panakkal explained. “We wanted the land to be transferred to the forest department and, as a response to our efforts, more than three years ago the revenue principal secretary asked the forest department to take it over.”

Though the land has been handed over to the forest department, no action has yet been taken to have it notified for conservation. “We keep hearing that this will be notified as a protected area because of its unique vegetation and biological diversity, but nothing has happened,” V.A. Abdul Khadar of NEWSI told indiaclimatedialogue.net

Significance of efforts

The efforts being made by the local citizens to conserve mangroves in the Chettuva river estuary is significant, since a study carried out to assess the status of mangroves in the state shows that Thrissur district has only 30 hectares under mangroves.

Protection of the mangrove patches requires assessing the ownership of the land on the riverbanks. As some of the rivers in Ernakulam, Thrissur, Malappuram and Kozhikode districts descend from the mountains through the midlands, they join an estuarine network that runs parallel to the coast. This water body runs parallel to part of the coastline in Kozhikode and Ernakulam districts, and the entire coastline in Thrissur and Malappuram districts.

Mangroves are almost gone from river banks. (Photo by S. Gopikrishna Warrier)
Mangroves are almost gone from river banks. (Photo by S. Gopikrishna Warrier)

“We pressurised the government to have the banks of the estuarine system in Thrissur district surveyed in 2010,” Panakkal said. “Even though the government informed us that they identified 45 acres of revenue land, there was no follow up action for getting encroachments removed and for conservation.”

Informed sources in the state government confirmed to indiaclimatedialogue.net

The group’s current endeavour is to protect a water body that is part of the Peringad River near Chettuva that measures some 234.18 acres. The edges of the body, which have patches of natural mangrove growth, are under pressure for conversion to tourism and shrimp aquaculture. “If the government protects this area, it will be a natural habitat for future generations,” said Panakkal.

With the revenue divisional officer having declared the area to be of government ownership (riverine revenue land), Panakkal and his team are working to get the government to have it surveyed to ascertain the boundaries. After this they are hoping that the government will use the area only for eco-friendly activities.

Healthy stands destroyed

According to P. Sujanapal, scientist at the Kerala Forest Research Institute and one of the two authors of the handbook on Kerala mangroves published by the Kerala State Biodiversity Board, the remaining mangrove patches around this water body were once healthy stands that got destroyed in the past two decades to construction, agriculture and shrimp farming.

“This patch of mangroves is a link between the terrestrial and coastal environment,” he said. Like the other mangrove patches in Kerala, this is part of a fast-disappearing habitat, and hence deserves conservation. These are fragile ecosystems that support traditional fishing, maintain the fresh and salt-water interface in the coastal areas and strengthen groundwater supply.

Bio-shields

“Mangroves are also effective bio-shields, protecting the coasts from erosion,” Sujanapal said. Chettuva is one of the areas where the coastline is protected by an artificial sea wall. Kerala has artificial sea walls along more than half its coastline.

The roots of the mangrove plants trap silt in the water and falling leaves from the plants get added to this. Thus a living and rising platform is created, which offers protection against an increase in sea level.

According to a study by the Kerala Forest Research Institute, mangroves, because of their numerous prop roots and other respiratory roots, form a skeletal biological mesh under the ground, much like a shallow geotextile. This root-textile is a porous mesh facilitating accumulation of debris. It does not yield easily to the tidal waves associated with natural disasters, as it holds the soil tight.

“The lesson that we learn from the last few decades of coastline protection activities is that the construction of sea walls and bay building are not as effective as the mangroves in calming down the invading sea,” says the report.

Rich biodiversity

The KFRI study notes that mangrove plants produce about one kg of litter (mainly leaves, twigs, bark, fruit and flowers) per sq. metre per year. Crabs consume some of this but most must be broken down before the nutrients become available to other animals. That is where the bacteria, along with fungi, come in. Dividing sometimes every few minutes, they feast on the litter, increasing its food value by reducing unusable carbohydrates and increasing the amount of proteins.

Fish and prawns then eat partly decomposed leaf particles, loaded with colonies of protein-rich microorganisms. They in turn produce waste that, along with the smallest mangrove debris, is munched up by molluscs and small crustaceans. Even dissolved substances are used by plankton or, if they land on the mud surface, are browsed by animals such as crabs and mud whelks.

The citizens’ group near Chettuva may not be aware of these scientific facts in detail, but having lived in the neighbourhood of these evergreen plants, they have a natural understanding of its benefits. Their aim is to get the remaining mangroves on government lands identified, so that it can be conserved for the present and the future.

This article first appeared on India Climate Dialogue.