Mangroves: The Coastal Superheroes

For over an hour, the boat I was in cruised the mangrove creeks and complex network of waterways in Coringa Wildlife Sanctuary (CWLS). On either side, the banks were a thick and complicated mesh of trees and plants above ground, their foliage hemming in and arching over the water. The roots were exposed and presented an equally complicated and dense latticework, disappearing into the greenish water. And whether it was the trees or the roots, it felt like an opaque curtain,and I couldn’t see beyond a couple of feet. I felt like an interloper, a rank outsider, against whom the forests were fiercely protecting their secrets.

Ever since I started reading the American poet Robert Frost several decades ago, “the woods are lovely, dark, and deep” felt like the perfect descriptor for a forest. The mangrove forests of the Godavari delta near Kakinada, Andhra Pradesh, especially within the protected area of CWLS, were lovely alright, but in a fierce, wild,and rugged way. They were dark and deep too, literally, but more so metaphorically. Anair of mystery, secrecy, intensity,and a profound sense of brooding seemed to hang over them. Traveling through these forests I felt that instead of Frost’s words, perhaps lines from Joseph Conrad’s Heart of Darkness were a more fitting description of the mangroves:“Trees, trees, millions of trees, massive, immense, running up high; and at their foot, hugging the bank against the stream, crept the little begrimed steamboat, like a sluggish beetle crawling on the floor of a lofty portico. It made you feel very small, very lost, and yet it was not altogether depressing, that feeling.”

Straddling land and sea and occupying intertidal zones, mangroves are exceptional spaces. Made up of unique trees, plants, and shrubs that can thrive in saline water, mangrove forests provide shelter to numerous species of animals, birds, insects, and marine creatures, their roots acting as protective nurseries. More importantly, the dense and intertwining roots shore up the soil, and the mangroves act as barriers against erosion, coastal storms, cyclones, tidal waves, and high-velocity winds, protecting coastal communities and agricultural land. They also trap fertile sediment brought by rivers, and enrich the soil, and become the source of livelihood for village communities that live beside them.

Beyond all these factors, mangroves play a far bigger and more critical role. They are powerful carbon sinks. Studies suggest they can sequester up to four times as much carbon as any other kind of forests, including rainforests, and reduce greenhouse gases. They are known to store the carbon in their leaves, which when dry, fall to the ground and are absorbed in the soil and stored in the sediment. It is estimated that carbon thus stored is locked away for thousands of years.

And yet, because they are less understood, and their importance underestimated, mangroves unfortunately also face severe threats and challenges. While deforestation for urban use, industrial activity, and agriculture are alarming concerns, the biggest threat is from aquaculture, especially shrimp farming (at least in CWLS), which uses precious mangrove land and water from the creeks for this purpose. More alarmingly, a study in 2018, by Jonathan Sanderman and 19 other researchers from around the world, indicated that mangrove destruction has released the trapped carbon into the atmosphere — as much as 122 million tonnes between the years 2000 and 2015. The same study also indicated that by 2000, the world’s mangroves held an estimated 6.4 billion metric tons of carbon. Take a moment to let those numbers sink in.

These numbers and facts weighed heavy on my mind as the boat I was in wound its way through the maze of creeks. In the Godavari delta, mangroves occupy an estimated 320 sq km making it the second-largest in the country after the Sundarbans. Of this area, 235 sq km has been declared protected area under the CWLS. These mangroves comprised over 35 plant and tree species, of which 16 are considered true mangrove varieties, while the others are termed associated species. Even though species such as the Ceriops decandra (gedara in Telugu) are on the IUCN’s Red List and categorised as “Near Threatened”, the mangroves of the Godavari delta are considered among the healthiest.

“Compared to the mangroves further south in the Krishna delta, which has almost the same type of species of trees and plants, the ones in the Godavari are much healthier, stronger and larger. It could be because the river still carries fertile sediment and communities have come to realise the importance of the mangroves and are protective of them,” said Rajahmahendravaram Divisional Forest Officer (Wildlife) Anant Shankar, whose jurisdiction includes CWLS.

Just how imperative the mangroves are to their safety is something the communities know well, especially every time the Bay of Bengal churns with a storm or cyclone. Community engagement is evident in this zone, where villagers have resisted encroachment and reported cases to authorities; in one instance they were even willing to testify in court. Locals say that Kakinada and nearby villages that rely on the mangroves have been untouched so far, while the surrounding areas not protected by mangroves have faced frequent devastation. I was told that the coastal road to Uppada, a mere 10 km north of Kakinada, is swept away every year despite several kilometres of stacked dolosse (concrete blocks).

In fact, the Godavari mangroves are among the few areas where the forests have been growing, especially on the landward side, while constantly facing threat from aquaculture. Images of row upon row of shallow aquaculture ponds that I had seen on the highway and outside most villages in the area were a stark reminder of the existential threat the fragile mangrove ecosystem faces. “The bigger problem is when the water from the ponds is released back into the creeks without treatment. If the cultivated fish or shrimp have contracted diseases, then the whole marine life of the mangroves can potentially be affected and masses can be wiped out instantly,” pointed out my guide Srikanth Mannepuri, who has been researching and documenting aspects of the mangroves in the East Godavari district. He referred to intermittent reports of fish being killed along the coast, and speculated whether aquaculture could be the culprit.

The CWLS also faces another looming problem — the Polavaram Dam which is under construction on the Godavari, upriver from Rajamahendravaram. Once the river is dammed, it will affect the outflow reaching the mangroves, which in turn will upset the delicate salinity balance. The dam will also stop all sediment from reaching the mangroves, which is essential for soil fertility and health of the mangroves.

As these various factors swirled around, Conrad re-entered my head. It was tempting to get depressed. But it was difficult to ignore the bright sparks in the gloom — passionate researchers and activists, a responsive administration keen on creating awareness, and villagers protective of their habitat. The sun, which had briefly gone behind a cloud, emerged again, filtering through the dense canopy and throwing dappled patterns on the water. Perhaps that was an allegory for hope.

A LITTLE LIFE

Like almost everything else about them, mangroves have a unique way of propagating their species. While traditionally seeds of trees fall to ground, get buried, germinate and grow into new plants, mangroves do it slightly differently. Mangrove species are viviparous, like mammals, and demonstrate embryonic activity. Seeds germinate on the tree itself, sometimes growing up to a foot in length and even develop roots; these are called propagules. They then detach and drop on to the forest floor, or into the water, and tidal activity carries them away from the parent. When they find the right conditions, they easily attach to soft mud and take root.