- The Pulicat lagoon located north of Chennai city, provides many ecosystem services that are crucial for the safety and survival of wildlife and humans residing around the lagoon.
- Studies find that the brackish water system is under various anthropogenic and environmental threats that are slowly shrinking it and ruining its characteristics.
- Experts argue in favour of health assessment of ecosystems like Pulicat and red listing them to provide the best protection.
“If the Pulicat lagoon dies, there will not be any rain in Chennai,” said architect and researcher Xavier Benedict of the Art & Architecture Research Development and Education (AARDE) Foundation, while driving the point home on the need to assess the health of crucial ecosystems like Pulicat using the Red List of Ecosystems (RLE).
IUCN’s (International Union for Conservation of Nature) Red List of Ecosystems by the CEM (Commission on Ecosystem Management) is a global standard for assessing risks to ecosystems. RLE seeks to assess the health of an ecosystem and acts as a tool to monitor the status of important ecosystems of the world.
Benedict was speaking at the IUCN Asia Consultative Workshop on Ecosystems and Nature-based Solutions held at Kerala Forest Research Institute (KFRI) in Peechi, Thrissur, in March 2023 to discuss the red listing of ecosystems in India.
Ecosystem services provided by the Pulicat lagoon
The second largest wetland in India, located north of Chennai city along the Coromandel coast, Pulicat lagoon (also known as Pazhaverkadu), is a brackish water system, spread over an area of 759 square kilometres (average area of the water spread is 461 square kilometres). Recent research attempts to comprehensively study the multitude of ecosystem services provided by this coastal lagoon and assign economic value to them. The lagoon is intricately linked to the livelihoods of a population of 33,550 in the 17 lagoon villages dependent on it and provides provisioning and regulatory services by way of fisheries.
It acts as a habitat for birds, animals, wetland mangrove systems and humans; as a buffer against natural disaster; and livelihood enhancement through value-added products, to name a few. The lagoon supports tourism, forms a base for the Indian Space Research Organisation (ISRO) from the sand barrier island at Sriharikota, and is a hub for indigenous knowledge to tackle climate change impacts.
The fisher communities that reside in the area follow a unique estuarine resource management system, called the padu system, wherein the fishermen rotate fishing rights among themselves. This helps promote and preserve sustainable fisheries in the region, thereby nurturing a sense of collective social responsibility and awareness of their resource territories. The research puts forward the argument that these nature-culture linkages have protected the lagoon from all destructive intrusion by way of infrastructure or industries, showing how biodiversity can be conserved through sustainable management of economic activities.
A buffer against disasters
Speaking to Mongabay-India, Benedict said that he has historical data of 40 years that prove that the eyes of many cyclones fall on the lagoon which acts as a buffer, protecting the Chennai city and surrounding areas against the disastrous effect of cyclonic storms and tsunamis. Tamil Nadu’s dependence on coastal lagoons and wetlands for safety and survival against climate vagaries goes beyond just this. The state hinges on the Northeast (NE) monsoon for showers. “Since only Tamil Nadu and coastal Andhra Pradesh depend on NE monsoon for rains in India, it is not very well represented in the government policies which are focused on Southwest monsoon,” he said.
Despite the lagoon’s prominence, both anthropogenic interventions and environmental changes are threatening its existence. Almost 80 percent of the mangroves which once dominated the wetland have vanished. Siltation or sedimentation is a major ecological problem that has led to the degradation of the Pulicat lake, its biodiversity, fisheries and livelihood of its fisher folk. Of the three mouths that the lagoon has, only one is open. The other two are in the north with one inside the ISRO island which is not dredged due to security reasons, leaving the northern part of the lagoon dry for the most part of the year.
While India is making huge strides in space science and innovation from ISRO, the rainfall pattern around the Pulicat lagoon is changing, said Benedict, who has studied the phenomenon. He has examined the rainfall pattern with periods of rocket launches from ISRO and has found out that rocket launches disturb the atmospheric clouds that get scattered, leading to a delay in rainfall. This, in turn, changes the land-use and land-cover pattern in the area.
Changing hydrological regime threatens species
As cyclonic events over the Bay of Bengal increase due to climate change, scientists fear that the salinity of the brackish water lagoon as well as that of the Bay of Bengal could be affected in the long run. A study published in 2018 revealed the extreme Chennai floods in 2015 caused almost 40 percent desalination of the lagoon.
“It is not necessary that every cyclone will have an effect on the salinity of the lagoon. For example, Cyclone Mandu did not affect Pulicat’s salinity but the 2015 floods did,” said Harini Santhanam, head of the Department of Public Policy at Manipal Academy of Higher Education and one of the authors of the study. The study contends that Pulicat could be a major exporter of low-saline waters to the Bay of Bengal, which is already a low-saline sea, thanks to freshwater exports from riverine systems like Ganges and Brahmaputra.
Santhanam added that almost 80 percent of the ecosystem services of Pulicat lagoon are met by the fisheries including the prawn and shrimp farming that produces export-quality prawns. “Fishers have been reporting reduced yield of prawns of late, which may only be a part of the big issue,” she said. “The reduction in prawn seeds is a cause of serious concern.” The seagrass community in the lake that forms the nursery for the fingerlings is sensitive to the change in the hydrological regime of the lagoon. Santhanam informed that change in salinity can prove detrimental to the prawn cultivation at Pulicat if the seagrasses disappear.
Experts also point to the reduction in the number of flamingos visiting the lake which they say, can lead to a further reduction in the fish population since their droppings act as fodder for certain fish species. Shalini Dhyani, a scientist at CSIR (Council of Scientific and Industrial Research)-NEERI (National Environmental Engineering Institute) said that studies on landuse land–cover changes and spatiotemporal analyses have proven beyond doubt that this unique ecosystem is undergoing ruination.
While certain anthropogenic influences cannot be avoided, experts such as Dhyani said they believe that considering the number of ecosystem services it provides, a conservation approach that recognises the lake as a nature-based solution and places society at the centre of conservation would work well since it would generate a sense of responsibility and belonging among the communities dependent on it.
The Pulicat lagoon system is ecologically so crucial to Tamil Nadu that it cannot be allowed to be ruined further, said Benedict. Land sharks would grab the lake if it dies, he added, and that would be too costly for the state.
“The Ramsar status for Chilika lake played a crucial role in protecting it,” Dhyani added. “Despite Pulicat’s support in ecosystem services, it has not received appropriate conservation status so far. Unlike species, ecosystems cannot be recovered once they collapse, ecosystem health assessment by IUCN using red listing is very important to assess Pulicat’s status for better conservation and restoration efforts,” she said.
Banner image: Fishermen engaged in seine net fishing at the Pulicat lagoon. Photo by Xavier Benedict, AARDE Foundation.