I have been exploring Mumbai’s coastline for over three decades in search of birds, crabs, fish and other marine fauna. The initial years were centred around beaches and inter-tidal zones that harboured fascinating biodiversity. But eventually, I started noticing the mudflats and the mangroves around them. It was a while until I took serious note of them, as all agencies considered them wastelands and dumping grounds for all sorts of urban waste. But one nature walk in the Godrej Mangroves, way back in 1988, changed my perception of the oxygen-deficient marshlands.
Mangroves at Vasai Fort
It was a late summer walk and I had sighted an Osprey swoop down and catch a mud-skipper. And, just as I was about to get my primitive camera out, the flying ghost disappeared into the dense mangroves.
Mangroves are not any single plant species but an entire habitat in which a whole community of plants are found. The habitat spans from the landward freshwater side to the saline seaward side, with specialised brackish water plants adapted to hours of submergence under tidewaters. Around 35 species of true mangroves plants have been described in India. Of these, 20 have been identified along coastal Maharashtra and 15 are found around the mouths of
Mangroves are a rich and economically important ecosystem that thrive in the tidal mudflats in tropical and sub-tropical regions. Due to the daily influx and outflow of tides, mangrove plants are forced to be salt-tolerant and hence, referred to as halophytes. Due to the excessive water and silt brought in by the river and sea, there is a perpetual shortage of dissolved oxygen, due to the large quantities of decaying matter. Mangrove plants have specialised breathing roots that project out of the soil, called pneumatophores. Their submerged, anchorage roots selectively absorb water while limiting salt intake. Some plants also have specialised salt and water exuding glands in their leaves.
With respect to Mumbai’s islands, mangroves locally called Tiwar are one of the most important ecosystems, as they cushion the land from the ingression of the sea. The original island owners, Kolis (local fishing community) worship the mangroves as they are breeding grounds for most fish and home to many medicinal plants. They use the wood of mangrove trees for house building, furniture, as fuel and in their fishing activities.
In the early 1990s, over 37 sq km of mangroves existed in and around Mumbai, largely in the Thane creek, Sewri-Mahul Bay, Mahim, Versova, Gorai and Ghodbunder region. There were also mangroves along the coast of Bandra, Malabar Hill and Colaba. Over the last century, land reclamation has substantially increased city boundaries. But, within the last decade, we have lost over 40 per cent of our mangrove cover. The same reclamation and linear construction such as jetties, bridges and promenades, have resulted in the emergence of new mangrove areas, such as those along Bandra Bandstand, the Palm Beach Road (Navi Mumbai) and in the Bhayander region.
Avicennia marina is the most common mangrove species in Mumbai, along with Meswak (Salvadora persica) and Sea Holly (Acanthus ilicifolius). Sadly, they have to tolerate heavy levels of industrial and household pollution, which includes heavy metals such as lead, mercury and chromium.
Mangrove forests are perfect examples of the resilience of nature and they thrive in the harshest of field conditions. However, there is an increasing fad among corporates and NGOs to spend lakhs on planting mangrove saplings. What one needs to do is clean up our mudflats of plastic and spilled fossil fuel. These mangroves, which are home to fish and crab, will automatically replenish fishermen’s nets.
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