World Mangrove Day: Conserving the sentinels of our coastline

26 July is International Day for Conservation of Mangrove Ecosystems. Adopted by the General Conference of the United Nations Educational, Scientific, and Cultural Organization in 2015, the day is celebrated to raise awareness of mangrove ecosystems as “a unique, special and vulnerable ecosystem” and to promote solutions for their sustainable management, conservation and uses. Mangroves are often called ‘sentinels of the coast’ given their ability to protect shorelines, absorb impacts of storms and cyclones, support fish nurseries, lock up carbon and nutrients, provide a gene pool, and myriad benefits.

Mangrove conservation in India is an impressive turnaround story. As per biennial assessments published by the Forest Survey of India, the extent of mangroves in the country has increased from 4,046 sq km in 1987 to 4,992 sq km in 2019. The Global Mangrove Alliance, which maintains consistent global datasets on mangrove cover, has estimated that worldwide, since 1996, there has been a net global loss of mangrove cover by 3.4%, with the losses having occurred globally at rates twice the gains. India is one of the few countries with positive trends in mangrove cover. This success is attributed to immense efforts in mangrove plantations based on localised models, community engagement in their protection and upkeep and strengthening coastal zone regulation architecture. States like Maharashtra have established a separate Mangrove Cell to ensure a consistent focus on the conservation and management of these ecosystems.

Yet, there are worrying trends. The National Decadal Wetland Change Atlas, published by Space Application Center in February 2022, reports that between 2006/7 and 2018/18, the natural coastal wetlands declined from 3.69 million ha to 3.62 million ha. The intertidal mudflats have decreased by a whopping 116,897 ha, and salt marshes by 5,647 ha. Mangrove plantation over intertidal mudflats is a prominent reason for this loss.

The intertidal flats, the area of the coast comprised of sand, rock or mud, and inundated by the tidal waters, are critical habitats for birds, especially migratory shorebirds and numerous other species. The flats also lock up immense amounts of carbon in the mud. Thus, mangrove plantation on mudflats is equivalent to converting one wetland type to another, and a gain in mangrove area is due to the loss of critical functions that the mudflats provide. And more so, intertidal flats are a crucial ecosystem under tremendous pressure from coastal development, reduced sediment delivery from major rivers, sinking river deltas, increased coastal erosion and sea-level rise. Worldwide, it is estimated that one-sixth of intertidal flats were lost during 1984-2016.

Planting mangrove propagules is the favoured method of mangrove restoration. In most mangrove areas, plantation is done to restore degraded areas or to create newer areas under mangroves. Plantation has become highly popular after the 2004 Indian Ocean Tsunami, and every year, a massive area is taken up for plantation with government funds, as well as with funds provided by donors and the private sector.

However, the efficiency of mangrove plantations has come under increasing scrutiny for their low efficiency, such as low survival rates. The majority of plantation efforts fail to effectively restore functional mangroves. And the fact that mangrove plantations do not address the drivers underpinning their degradation and loss.

Mangroves are under pressure for various reasons - including over-harvesting, pollution, agriculture conversion, aquaculture, urbanisation, infrastructure development, and others. Often reduced freshwater flows to the coast cut off the supply of freshwater and sediments to the coastline, creating high salinity and low sediment conditions that mangroves cannot sustain.

Lesser sediments coupled with climate change-induced sea-level rise and extreme events lead to erosion of the coastline, and its habitats, including mangroves. Mangrove restoration, therefore, needs a wider set of approaches - which include ensuring sufficient freshwater and sediments flow to the coast, preventing pollution and regulating infrastructure development. Equally critical is ensuring the livelihoods of coastal communities, which depend on these ecosystems and hold significant knowledge of their values and functioning.

Climate change is altering our coastline in fundamental ways - the sea levels are rising, sea surface temperatures are increasing, and the frequency and severity of coastal storms are on the rise. A 2-degree warmer world may increase mangrove growth and productivity. Yet, these ecosystems stand to be adversely impacted by the increase in cyclonic activity, sea level rise and decline in summer precipitation. The ability of mangroves to sustain under a changing climate is also linked with the availability of accommodation space - the space available for mangroves and other coastal ecosystems for vertical and lateral adjustments as sea level changes and involving the accumulation of sediments. The lack of accommodation space may be a critical barrier for several cities with intensive build-up along mangroves, such as Mangroves of Thane Creek in Mumbai. An accommodation buffer may be needed to prevent the coastal squeeze for newly developing areas around coastal ecosystems.

Most of our management plans for coastal areas are akin to driving looking into the rearview mirror. Conditions of the ecosystem in the past - say in the sixties or seventies guide goal and outcome setting. However, the past becomes a poor predictor of the future with a changing climate. Management should rather be looking into future scenarios, informed by tremendous advances in climate modelling and integrate suitable mitigation and adaptation options while implementing management plans.

India’s 2030 vision of becoming a five trillion economy rests on ten elements  - one of which is the blue economy - the economy sustained by coasts and oceans. Ensuring that our sentinels of the coast are conserved and effectively managed is critical to this goal. And this would require that mangrove conservation efforts incorporate major policy and programming shifts.

Firstly, the policy targets should broaden from increasing mangrove cover to improving coastal ecosystem health. Mangroves are not just groves of salt-tolerant trees but stand enmeshed with other coastal ecosystems such as mudflats, lagoons, estuaries, salt marshes and numerous others. Sustaining the entire coastal ecosystem’s diversity and resilience and the lives and livelihoods of coastal communities is a more meaningful outcome.   Secondly, managing mangroves and coastal ecosystems must factor in climate risks and include necessary adaptation and mitigation options.

The available climate models would need to be downscaled and interpreted at the scales wherein hydrological and ecological processes affecting mangroves and coastal ecosystems make sense. Thirdly, the toolkit of mangrove restoration should be widened to include not just silvicultural measures but also restoration of hydrological and sediment regimes and blended grey-green solutions.

Fourthly, the ecological and hydrological needs of mangroves and coastal ecosystems must be factored in sector plans for water resources, disaster risk reduction, fisheries, tourism and others. And finally, the multiple values of coastal ecosystems need to be assessed and form the basis of societal behaviour change at all levels towards building coastal resilience. Adopting an inclusive “all of society” approach should be the core of this approach. 

The newly instituted ‘National Coastal Mission’ within the Ministry of Environment, Forest and Climate Change can be a harbinger of the above-mentioned changes. 

Dr Ritesh Kumar is the Director of Wetlands International South Asia. Views expressed are personal. 

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