Sankar grew up listening to stories of rain. For in Muthupet, where the 54-year-old’s family has been residing for about 250 years, it was the rainfall which nourished an extensive mangrove forest. Over the last 20 years, however, as the rainfall pattern changed, so did the biodiversity of the area.

Muthupet or Muthupettai, located in Thiruvarur district in Tamil Nadu, used to receive copious amounts of rainfall stretched across seven months. This resulted in the inflow of freshwater into the mangrove forests through fishing canals. Mangroves are salt-tolerant species and they depend on a delicate balance of fresh and seawater. In the last two decades, as the quantity of fresh water flowing into these canals dwindled, owing to scarce rainfall; the salinity levels in the region increased.

As the salinity levels rose, some mangrove species with greater sensitivity to soil salinity began to die out. This in turn affected communities that depended on the mangroves for their livelihood – communities that included Sankar’s family.

“I have heard from my father and grandfather how we used to receive heavy rainfall three times a year between July and September. They would use the Tamil proverb matham mummarri pozhigiradhu to describe it,” says Sankar, who goes by one name. The proverb literally translates to three months of heavy rainfall as “matham” means month, “mum” is three, “marri” is rain and “pozhigiradhu” refers to pouring copiously.

This was corroborated by V. Selvam, former lead researcher on mangroves at the M.S. Swaminathan Research Foundation (MSSRF), Chennai. “I used to live in that region while doing my Ph.D. from 1983 to 1986 and have witnessed the monsoon setting in around July 15 every year,” he says.

Low-salt tolerant mangroves become locally extinct

Selvam, who has also worked closely with Sankar on mangrove conservation programmes, says that in the last few decades, about five low-salt tolerant mangrove species became locally extinct because of the increase in soil salinity.

“Over the last seven decades, increasing salinity levels in Muthupet have pushed species like Xylocarpus granatum, Sonneratia apetala, Kandelia candel, Cynometra iripa and Bruguiera gymnorhiza to local extinction. Other low-salt tolerant species are also disappearing gradually,” Selvam tells Mongabay-India.

A study published in 2013 by Rajarshi Das Gupta and Rajib Shaw from Graduate School of Global Environmental Studies, Kyoto University, Japan, on Cumulative Impacts of Human Interventions and Climate Change on Mangrove Ecosystems of South and Southeast Asia also highlighted the connection between the loss of species biodiversity and livelihood.

It stated, “Potential consequences of the loss of mangroves in this region are multifaceted with distinct ecological, social, and economic dimensions. In many remote coastal areas of this region, mangrove-based livelihood opportunities strongly define the social and economical well-being of the coastal communities.”

“Over the years, mangroves have sustained more than 70 direct human activities. Of these, on-shore fishing and timber and firewood collection are worth mentioning in the backdrop of South and Southeast Asia, where rural poverty still forms a critical sociopolitical issue. The degradation of mangroves has adversely impacted traditional fishing activities. Many aquatic species including the commercially important fishes were lost or significantly reduced along with the mangroves,” the study found.

Read more: How carbon cycles in Pichavaram mangroves

It is precisely the reason why conservation of mangrove diversity is important and this is where Sankar steps in.

Driven by a sense of urgency to protect the ecosystem which has been a source of livelihood for his family and community for generations, Sankar began to seek out organisations and agencies that could help him understand the science behind the importance of mangroves. In 1997, the then 30-year-old enlisted help from MSSRF.

“I knew how marine animals make the roots of the mangroves their home and how they are also sometimes used as breeding areas, but after my association with scientists and researchers, I got to know how mangroves help in maintaining an ecological balance among the sea, the land and the rivers,” says Sankar, a fisherman.