Keywords

3.1 Introduction

Mangroves are the only tall tree forest on the Earth, lying between the land and sea in the tropical and subtropical regions of the world. This is one among the most productive forest ecosystems. It is a rare forest type with 73 tree species, in 15.2 million hectares in 123 countries, between 30° south and 30° north (FAO 2007). Mangroves are carbon-rich forest with biomass greater than any other aquatic systems on the Earth. The mangrove systems have diversified habitats, such as core forests, litter-forest floors, mudflats, adjacent coral reef and sea grass systems, and contiguous water bodies such as bays, estuaries, lagoons, and backwaters. These habitats support genetically diverse groups of both terrestrial and aquatic organisms, and hence mangroves are biologically diverse and ecologically dynamic. Mangroves are extraordinary to thrive in the habitat of varying salinity, tidal regime, strong wind velocity, high temperature, and muddy anaerobic soil where no other trees can survive. Mangroves are also structurally and functionally unique to have well-developed aerial roots, viviparous germination, absence of growth rings in wood, adaptable to high salinity and climate changes, and highly efficient in nutrient retention. The mangrove forest ecosystem is a complex of plant, animal, and microbial communities and their nonliving environment interacting as a functional unit. Mangroves are also ecologically significant and economically important in enriching coastal biodiversity, in supporting fisheries, in yielding commercial forest products, and in protecting coastlines from fiery effects of cyclone, flood, waves, and other natural calamities. They are also known as “oceanic rain forest,” “tidal forest,” “root of the sea,” “Blue Carbon Forests” and “coastal woodlands” (Kathiresan and Bingham 2001; Kathiresan and Qasim 2005). Under such diverse and valued ecosystem services, this present chapter provides an insight into the current status of mangrove cover and biodiversity, impacts of climate change, and managerial strategies followed under promotary, regulatory, and participatory aspects to mitigate the impacts of climate change on mangrove forest ecosystems of India.

3.2 Mangrove Distribution in India

3.2.1 Mangrove Forest Coverage

India has a total area of 4740 sq. km under mangroves, accounting for 2.8 percent of the world’s mangrove vegetation and 0.14 percent of country’s total geographical area (SFR 2013). Mangroves are found along the coastlines of nine states and three union territories (Fig. 3.1). Mangroves in Sundarbans of West Bengal occupy 44 %, while mangroves in Gujarat have 23 percent of mangroves in India. In other words, 67 percent of Indian mangroves are present only in the two states of India: West Bengal and Gujarat. About 58 percent are found along the east coast (Bay of Bengal), 29 percent on the west coast (Arabian Sea), and the remaining 13 percent on the Andaman and Nicobar Islands.

Fig. 3.1
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Mangrove areas of India

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There are three major types of coastal settings on which mangroves exist in India, and they are deltaic, backwater-estuarine, and insular types. The deltaic mangroves occur along the east coast where the mighty rivers (Ganga, Brahmaputra, Mahanadhi, Krishna, Godavari, and Cauvery) make the deltas. The backwater-estuarine type of mangroves that exists in the west coast is characterized by typical funnel-shaped estuaries of major rivers (Indus, Narmada, Tapti) or backwater, creeks, and neritic inlets. The insular mangroves are present in the Andaman and Nicobar Islands, where many tidal estuaries, small rivers, neritic islets, and lagoons support a rich mangrove forest. The differences in mangrove distribution can be attributed to two reasons: (i) the east coast has large estuaries with deltas formed by runoff and deposition of sediments, whereas the west coast has funnel-shaped estuaries and generally lacks deltas; and (ii) the east coast has a gentle slope with extensive intertidal mudflats for mangrove colonization, whereas the west coast slopes steeply (Fig. 3.2). It is expected that mangroves along the east coast of

Fig. 3.2
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A cross section from Daman and Cuttack showing the gradients along the east and west coasts of India (values not to scale). The east coast with smooth slope may be more vulnerable to sea level rise than the west coast with steep slope (distance from west and east coast (from Daman to Cuttack))

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India may be vulnerable to sea level rise, more than the west coast of India. The coastal zone of the west coast is narrow and steep in slope with no major inflowing river. Thus, mangroves of the west coast are smaller in size, less diverse, and less complex as compared to east coast which has larger deltas created by east flowing rivers and gentle slope of the coast.

The environmental setting of mangroves of India can also be classified into four types: tide dominated, river dominated, drowned bedrock valley, and carbonate platform on low-energy coast (Selvam 2003). Sundarbans in West Bengal and Mahanadi mangroves in Odisha are of tide-dominated type, characterized by high tide range with strong bidirectional current. Krishna and Godavari mangroves in Andhra Pradesh, Muthupet, and Pichavaram in Tamil Nadu are of river-dominated type, characterized by rapid deposition of terrigenous materials that form active delta toward the sea. Gulf of Kutchch and Gulf of Khambhat mangroves in Gujarat are of drowned bedrock valley type due to rising sea level. Andaman and Nicobar Islands are of carbonate platform on low-energy coast type, characterized by accretion due to accumulation peat and calcareous materials, which mitigate wave energy and allow mangroves to grow extensively in coastal fringes. In India, the tide-dominated mangrove type occupies 49.3 % (2337 sq.km) of total mangrove cover area. The drowned bedrock valley type occupies 23.4 % (1107 sq.km), whereas the river-dominated type and carbonate platform types occupy only 0.3 % (414 sq.km) and 13 % (617 sq.km), respectively. In other words, the tide-dominated type of coastal setting favors extensive mangrove colonization followed by drowned bedrock valley, carbonate platform type, and river-dominated type.

3.3 Status of Forest Cover

Mangrove cover is classified in terms of density of cover as very dense, moderately dense, and open types based on percent of its green cover: >70 %, 40–70 %, and 10–40 %, respectively. The extent of very dense cover is 1472 sq. km (31 %), moderately dense is 1391 sq. km (29 %), and open type is 1877 (40 %) (Table 3.1; SFR 2013). Among these types, the open type of mangroves may be more vulnerable to climate change, especially sea level rise in Andhra Pradesh, Tamil Nadu, Kerala, Gujarat, Maharashtra, and Puducherry, than the dense and very dense mangrove types.

Table 3.1 Mangrove covers in different states/union territories of India and trend of change (STR 2015)
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3.3.1 Trends of Change

India had a mangrove cover of about 6000 sq. km during the 1960s and reduced to 4046 sq. km in 1987. However, since 1995 the extent of mangrove cover since 1995 got stabilized close to 4500 sq. km with an increasing trend (SFR 2013; Bhatt and Kathiresan 2012). Compared with 2013 assessment, there was a net increase of 112 sq km in the mangrove cover of the country, assessed during 2015 (Table 3.1). The Forest Survey of India assessed the mangroves at 1:1 million scale in 1987, subsequently at 1:2,50,000 scale from 1989 to 1999 for every 2 years, and at 1:50,000 scale from 2001 onward. In general, mangroves are well protected in 38 selected areas along the Indian coastline, in spite of the growing threats by humans and nature. This is due to the efforts of Government of India in taking all necessary measures through conservation, restoration, as well as rehabilitation of degrading mangroves, in cooperation with different states and union territories of the country.

3.4 Biodiversity Status of Mangroves in India

A total number of floral and faunal species reportedly present in mangrove forests of India are shown in Table 3.2 (Kathiresan 2004). There are only 39 core mangrove species which support 3972 other biological species that include mangrove associates, sea grass, marine algae, microbes, lichens, prawns, lobsters, crabs, insects, mollusks, finfish, amphibians, reptiles, birds, and mammals. In other words, each mangrove species supports about 100 other biological species. Altogether 4011 species consisting of 920 floral and 3091 faunal species are reportedly present in mangrove ecosystems of India. In other words, the animal component occupies 77 percent and the botanical component 23 percent, and thus the faunal component is about 3.5-fold higher than floral component. No other country in the world has recorded so many species to be present in mangrove ecosystems.

Table 3.2 Total numbers of floral and faunal species recorded in mangrove forests of India
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Globally there are 11 threatened mangrove species under IUCN category. Of which, two species are found to be present in India. They are Sonneratia griffithii and Heritiera fomes which are rare due to low-seed viability and slow growing. A natural hybrid species, Rhizophora annamalayana, is endemic to Pichavaram mangrove forest and is critically endangered (Kathiresan 1999). These species are being recovered and regenerated (Kathiresan 2010).

Globally there are 11 threatened mangrove species under IUCN category. Of which, two species are found to be present in India. They are Sonneratia griffithii and Heritiera fomes which are rare due to low-seed viability and slow growing. A natural hybrid species, Rhizophora annamalayana, is endemic to Pichavaram mangrove forest and is critically endangered (Kathiresan 1999). These species are being recovered and regenerated (Kathiresan 2010).

In Indian mangroves, invasive alien species do occur, and they disrupt ecological balance of mangrove ecosystem. Some examples are (i) aggressive growth of Prosopis species in Tamil Nadu and Andhra Pradesh, (ii) strangulating of the mangroves by a climber Derris trifoliata in Sundarbans, and (iii) prolific growth of the aquatic weeds such as Eichhornia crassipes and Salvinia in mangrove waters with low salinity in Kerala, Andhra Pradesh, and Tamil Nadu (Raghubanshi et al. 2005).

In India, the most spectacular natural treasures are the dense mangrove forests inhabited by endangered tiger, the sandy coast with the world’s largest nesting site of sea turtles (olive ridley), the intertidal mudflats teeming with migratory birds (about 2 million water birds of 200 species), the delicate sea grass meadows favored by the sea cow (dugong), the most beautiful coral reefs colonized with ornamental fishes, and the rough sea of Gujarat migrated with the largest whale shark fish. It is worthwhile to mention that Bhitarkanika in Odisha state is the mangrove genetic paradise of the world and yet another paradise is in Baimaru in New Guinea. Sundarbans in India and Bangladesh is the largest single block (with about 10,000 sq. km) in the world and is the only mangrove forest colonized with threatened Royal Bengal Tiger. The Sundarbans is the home of globally threatened species such as fishing cat, Gangetic dolphin, estuarine crocodile, horseshoe crabs, water monitor lizard, and river terrapins. The Sundarbans is a recognized International Biosphere Reserve as well as World Heritage Site of the UNESCO.

Mangrove habitat loss is either man-made or natural, and this may cause a depletion of rich biodiversity of the mangrove ecosystems. However, in the mangrove ecosystems, there are some genetically superior organisms, which can overcome the impact of climatic change. It is, therefore, suggested as a long-term plan (i) to identify the mangrove genotypes and fauna which are tolerant to temperature and flooding, (ii) to propagate those genotypes, and (iii) to create new hybrid species from those genotypes, for biodiversity enrichment and coastal protection against the climate change.

3.5 Impact of Climate Change on Indian Mangroves

Mangroves are likely to be one of the first ecosystems to be affected by the growing threat of climate change especially sea level rise, because of their location at the interface between the land and sea. The factors of climate change include changes in temperature, carbon dioxide, precipitation, hurricanes, storms, and sea level. All these factors are synergistically acting upon the mangroves. However, mangroves exhibit resistance and resilience to overcome potential impacts of climate change. Resistance of mangroves is the ability to withstand the disturbances, whereas resilience of mangroves is the ability to recover from the disturbances. However, the mangroves may be vulnerable to sea level rise, and the extent and composition of mangroves may undergo changes (Kathiresan 2014).

3.5.1 Sea Level Rise

Sea level rise is the top most challenge of mangroves to climate change. The projected sea level rise is 30 cm in the coming 50 years in India (Vivekanandan 2011). In Indian Sundarbans, two islands, namely, Suparibhanga and Lohacharra, have recently submerged, and a dozen other islands on the western end of the inner estuary delta are under the threat of submergence (http://www.thedailystar.net/2006/12/22/d61222011611.htm).

Mangroves can adapt to sea level rise if it occurs slowly enough and if adequate expansion space exists. As the sea level rises, mangroves would tend to shift landward. Human encroachment at the landward periphery, however, makes this difficult. Consequently, the width of mangrove systems may decrease with the sea level rise. The ability of mangrove migration landward is also determined by local conditions, such as infrastructure (roads, dikes, urbanization, seawalls) and topography (steep slopes).

Tidal range and sediment supply are two critical indicators of mangrove response to sea level rise. In general, the mangroves with macro-tidal and sediment-rich areas are able to survive sea level rise than those with micro-tidal and sediment-starved areas. The sedimentation is highest in Sundarbans (1130 t/km2/yr) with extensive mangrove colonization, and it is lowest (115 t/km2/yr) in Cauvery delta of Tamil Nadu with less mangrove cover. Moreover, Gujarat and Sundarbans are macro-tidal with high range of tides 5–8 m, and the mangrove areas here are extensive due to the occurrence of extensive intertidal areas, whereas Tamil Nadu, Kerala, and Karnataka are micro-tidal, and the mangrove areas here are less due to the occurrence of narrow intertidal areas (Kathiresan 2009). It is predicted that the mangroves of Sundarbans and Gujarat are comparatively less vulnerable to sea level rise than all other mangroves of India, especially those in Tamil Nadu and Kerala, which are also low-lying coastal areas.

It is believed that mangroves situated in riverine areas with dense mangrove forests are least vulnerable to sea level rise. Although mangroves of Tamil Nadu are located in Cauvery riverine areas, the mangroves are less dense due to the reduction in river water flow and monsoon failure, and hence the mangrove areas are vulnerable to sea level rise.

The most vulnerable mangroves to sea level change are believed to be located in areas with small islands, lack of rivers, carbonate settings, tectonic movements, groundwater extraction, underground mining, coastal development, and steep topography. The west coast of India has in general steep topography and sediment-starved condition. Coastal development and ground water extraction are widespread all along the Indian coast especially in Maharashtra, Gujarat, Odisha, Andhra Pradesh, and Tamil Nadu. Andaman and Nicobar Islands with small islands, lack of rivers, carbonate settings and tectonic movements are likely vulnerable to sea level change.

3.5.2 Cyclones and Storms

In addition to sea level rise, storm surges which are expected to increase in intensity of 5–10 % by the year 2050 can also flood the mangroves. The storms may affect mangrove health and species composition due to changes in salinity, recruitment, and inundation and changes in sedimentation. Avicennia and Sonneratia species are more vulnerable than Rhizophora species. This is due to stilt roots of Rhizophora species which stand above sea level rise than the pneumatophores of Avicennia and Sonneratia species which mostly submerge under the sea level rise. Moreover, stilt roots trap sediment and facilitate peat accumulation in the mangrove areas.

Tropical cyclones and storms are common in the Bay of Bengal. They severely affect the east coast as compared to the west coast of India. According to Koteswaram (1984), there were about 346 cyclones that include 133 severe ones in the Bay of Bengal, whereas the Arabian Sea had only 98 cyclones that include 55 severe ones between the years l891 and l970. These cyclones with tremendous speed hit the coastline and inundate the shores with strong tidal wave, severely destroying and disturbing coastal life. However, mangroves like Rhizophora spp. seem to act as a protective force toward this natural calamity. Generally, regeneration of mangroves like Avicennia species takes place after cyclones in these areas. Thus, mangroves are resistant to cyclones in India. The best example is the super-cyclone that occurred on the 29 October 1999 with a wind speed of 310 km/h along the Odisha coast in India. This cyclone played havoc, largely in the areas devoid of mangroves. On the contrary, practically no damage occurred in the areas with dense mangrove forest. This event killed almost 10,000 people and caused a massive loss of livestock and property. Had the mangrove forests been intact, more than 90% of the human deaths due to the 1999 cyclone would have been avoided. In the areas affected by storms and cyclones, the protection economic benefits of a hectare of land with mangroves can be nearly two times higher than the economic value of “cleared” land (Sudamanini Das 2007). Thus, mangrove conservation is an economically appropriate policy option, and therefore protecting mangroves as storm buffers generates more value to society.

3.5.3 Precipitation

Precipitation may increase by 25 % by 2050 due to global warming. However, both increases and decreases of precipitation are projected in different areas. In general, the areas with high precipitation are gifted with high biodiversity of mangroves and associated species. Changes in precipitation pattern may have a marked effect on the biodiversity, growth, productivity, and areal extent of mangroves. Decreased precipitation results in a decrease in seedling survival, and may change species composition, favoring more salt-tolerant species especially salt marsh species such as Suaeda, Sesuvium, etc. with projected increase of hypersaline mudflats especially in Gujarat, some parts of Tamil Nadu, and Andhra Pradesh.

In general, the current status indicates that except in Andaman and Nicobar Islands, in all the mangrove wetlands of India, low-saline-tolerant species are gradually disappearing, and species like Avicennia marina which can tolerate a high and broad range of salinity are becoming dominant. In Sundarbans, the freshwater-loving species such as Nypa fruticans and Heritiera fomes (“Sundari”) get reduced in population density, and these species are also getting replaced with salt-tolerant species such as Ceriops species belonging to the plant family Rhizophoraceae (VYAS 2012). In Muthupet, the true mangrove species belonging to Rhizophoraceae were dominant about 150 years ago but now they are locally extinct. Dense and tall trees of Avicennia officinalis, Excoecaria agallocha, and Lumnitzera racemosa constituted nearly 90 % of the population of the Godavari mangrove wetlands in the 1950s, but now they constitute only 37 % of the population and are replaced by salt marsh bushes of Suaeda maritima and S. nudiflora.

The main reason for such changes in mangrove species composition is the reduction in the periodicity and quantity of freshwater reaching the mangrove environment. This may be attributed to the monsoon failure, the exceeding evapotranspiration to precipitation, and the dam constructions in upstream areas for diverting the freshwater for irrigation purpose. The freshwater is required to moderate the salinity of water and also to dilute and disperse pollution in estuaries. The freshwater is required for germination and sprouting of seeds and seedlings of mangroves. Due to lack of adequate freshwater, several wildlife species got extinct in Sundarbans, and these were Javan rhino, water buffalo, swamp deer, barking deer, and sweet water turtle (Chaudhuri and Choudhury 1994). The fish stocks of mangrove estuaries are affected due to reduced flow of waters. This reduced flow of freshwater interferes with the migration of freshwater fishes for breeding from upland to coastal waters and also with the migration of marine fishes for breeding from sea to coastal waters as a result of siltation of river mouths due to reduced flow of freshwater in the estuaries.

Reduction in freshwater flow is one of the major threats to mangroves in India especially the West Bengal (Sundarbans), Odisha, Andhra Pradesh, and Tamil Nadu. This situation has made mangrove habitat increasingly saline and favoring colonization of salt-tolerant species. Moreover, the biomass and growth of the mangroves are also hampered in the areas of increasing salinity. Therefore, an interdisciplinary study should be initiated to find out how much freshwater a mangrove ecosystem requires to sustain itself. The results of this study can be utilized to convince people and policy-makers to allow flow of certain quantity of freshwater into mangroves during certain period in a year. This will ensure a long-term survival of the mangrove ecosystem, at least in its present status.

3.5.4 Temperature

Mangroves are not expected to be adversely affected by the projected increases in sea temperature of 2–6 °C by 2100. Temperature greater than 35 °C may alter root structure and seedling establishment. A small increase in temperature may not adversely affect the flowering, but may change their reproductive cycle, and thus may alter the duration between flowering and the fall of ripe seeds. The arid climate that prevails in the Gujarat and in some parts of Tamil Nadu and Andhra Pradesh is largely monospecific with Avicennia marina as this species is resistant to high temperature. At the same time, increased sediment temperature may increase growth rates of bacteria which are likely to increase recycling and regeneration of nutrients.

Sea surface temperature has increased by 0.2 to 0.3 °C along the Indian coast in the last 45 years and is projected to increase by 2.0 to 3.5 °C by 2099 (Vivekanandan 2011). Phytoplankton grow faster at elevated temperature, but the decay sets in earlier. Occurrence of harmful algal blooms may become more frequent, intense, and widespread and cause considerable mortality of fish. Mangrove-associated coral reef ecosystem is likely to face annual event of coral bleaching in the future, and it is expected that the coral reefs would soon start to decline and become remnant between 2050 and 2060 in the Indian seas. The elevated temperature may change composition and abundance of fish species and depend upon their tolerance. If small-sized, low-value fish species with rapid turnover of generations are able to adapt with changing climate, they may replace large-sized high-value species, which are already showing declining trends due to over-fishing and other non-climatic factors (Vivekanandan 2011).

3.5.5 CO2

The increase in CO2 may increase net photosynthesis and growth rate of mangroves when the soil salinity is low. However, the photosynthesis and growth rate may be reduced, when the salinity increases. One indirect effect of increase in temperature and CO2 is the degradation of coral reefs due to mass bleaching and impaired growth. As a result, protection function of the coral reefs from wave action will be lost, thereby affecting the mangroves. More studies are required on the role of microbes in carbon sequestration of the coastal vegetated habitats.

Mangroves are among the most carbon-rich forests in the tropics. This is because of high levels of belowground biomass and considerable storage of organic carbon in mangrove sediment soils. The mangrove wetlands are efficient habitats for carbon burial, about 2.4-fold as high as salt marshes and 5.2-fold as high as sea grasses. The mangroves sequester as much as four times the amount of carbon in their sediment per hectare of tropical forest (Duarte et al. 2005). Covering 2118 km2, the mangroves of the Indian Sundarbans are thought to absorb over 41.5 million tonnes of carbon dioxide daily, valued at around USD 79 billion in the international market. Maintaining this function will help to control rises in atmospheric temperatures and associated climatic change.

Globally, mangrove deforestation generates emissions of 0.02–0.12 picograms of carbon per year, up to 10 % of total emissions from deforestation (Donato et al. 2011). Thus, failing to preserve mangrove forests can cause considerable carbon emissions and lead to climate change. Therefore, mangrove restoration could be a novel mitigation option against climate change.

3.6 Management of Mangroves in India

3.6.1 Promotory Management of Mangroves

The Government of India launched a program on conservation and management of mangroves during 1987. The Government provides 100 % financial assistance through the Ministry of Environment, Forests and Climate Change for research and also for the implementation of approved “Management Action Plans” (MAP) for mangroves. The Government has identified 38 mangrove areas along coastal India for implementation of MAP. The MAP components are survey, assessment, and demarcation; capacity building; staff training and skills; shelterbelt development; protection and monitoring; restoration and regeneration measures; alternate and supplementary livelihoods; community participation; mangrove afforestation/plantation (in degraded areas and open mudflats); biodiversity conservation; sustainable resource development; de-silting; weed control; pollution control; environmental education and awareness; and impact assessment and evaluation of the MAP.

3.6.2 Regulatory Management of Mangroves

Most of the Indian mangrove forests are provided with the legislative protection under the Indian Forest Conservation Act, 1980, and the Wildlife (Protection) Act, 1972. The mangrove habitats are categorized as national park or wildlife sanctuary or reserve and protected forests and/or community reserves. Moreover, the up-gradation of designated status provides more legal protection to the mangrove forests. For instance, the Sundarbans mangroves were initially declared as the tiger reserve in the year 1973 and then as the wildlife sanctuary in 1977 and later declared as the national park (IUCN category II) in 1984. Similarly, the Bhitarkanika mangroves of Orissa were initially declared as Bhitarkanika wildlife sanctuary in the year 1975 and later elevated to the status of the national park in 1998 (DasGupta and Shaw 2013).

Integrated coastal zone management is actively now practiced in conservation and sustainable use of mangrove ecosystems. The Coastal Regulation Zone Notification (2011) under the Environmental Protection Act (1986) recognizes the mangrove areas as ecologically sensitive and categorizes them as CRZ-I (i). This implies that the mangrove areas are afforded protection of the highest order. The Coastal Regulation Zone (CRZ) Notification 2011 has replaced the CRZ Notification, 1991, after codifying 25 amendments. In addition, an Island Protection Zone Notification, 2011, has been notified covering Andaman and Nicobar Islands and Lakshadweep that include mangroves also. The State/UT Coastal Zone Management Authorities constituted at the 13 coastal states/UTs are responsible for enforcement and monitoring implementation of the Coastal Regulation Zone Notification in their respective states/UTs.

Several marine and coastal protected areas (MCPA) that include mangroves have been declared as per the Wildlife (Protection) Act, 1972, to conserve the mangrove biodiversity in the country. The problem here is the concept of MCPA is not a specific category in India, and it is widely used to declare national parks, sanctuaries, or tiger reserves in coastal or marine areas under the Wild Life Protection Act of 1972 (Rajagopalan 2011). Some examples are Sundarbans National Park, Coringa Wildlife Sanctuary, Bhitarkanika National Park, Gulf of Kachchh National Park, etc. However, the MCPA has some demerits: there is no significant participatory management, causing resentment of public, and the forest department (entrusted with management of MCPAs under the Wildlife Protection Act) is not much familiar with coastal and marine ecology and biological aspects.

Illegal destruction of mangroves is a violation of the Coastal Regulation Zone Notification, and it attracts the provisions of the Environment (Protection) Act, 1986. As per the said Act, the Ministry of Environment and Forests or any other authority that has been delegated with such powers can issue a direction to violators under Section 5 of the Act which includes closure of the unit and stoppage of electricity or water to such units. Noncompliance of the directions issued under Section 5 of the Act attracts Section 15 of the said Act which provides imprisonment for a term of 5 years with a fine which may exceed to one lakh rupee, or both and in case the failure to contravention continues, with additional fine which may extend to five thousand rupees every day. If the failure or the contravention continues beyond 1 year, the offender shall be punishable for a term which may extend to 7 years.

In addition to legal protection of mangroves, the state governments have fishery policies to sustain fisheries by regulating fishing activities. These include restricting the use of inshore waters for the exclusive use of artisanal fishermen, the ban on use of certain fishing methods such as the use of dynamites and explosives and a few specific gears, the ban on fishing by mechanized boats for 45 days from 15 April to 30 May in the east coast and for 65 days from 10 June to 15 August in the west coast, the regulation of minimum mesh size in the cod end of trawl net, and the ban on night trawling in certain parts of Tamil Nadu. According to the Coastal Regulation Zone Notification 2011, there are no restrictions being imposed on any fishing activities and allied activities of the traditional fishing communities in the water area up to 12 nautical miles. There are also special provisions given for the fishermen communities living along the coastal areas in Maharashtra, Goa, Kerala, Sundarbans, and other ecologically sensitive areas. The artisanal fishing uses nonmotorized fishing crafts and gears such as gillnetting for harvesting bottom or pelagic fish, hook and line, beach seines, and fish traps. These artisanal fisheries are benefited by the governmental practice of fishing holiday. Artisanal fishermen of South India are showing keen interest to put up artificial reefs to enhance fish production.

International cooperation: India promotes regional and international cooperations for implementation of strategies for conservation of ecosystems including mangroves. International agreements are the Convention on Biological Diversity (CBD); Convention on International Trade in Wild Species of Endangered Flora and Fauna (CITES); Ramsar Convention on Wetlands, World Heritage Convention, and Bonn Convention on Conservation of Migratory Species (CMS); United Nations Framework Convention on Climate Change (UNFCCC); United Nations Convention to Combat Desertification (UNCCD); Commission on Sustainable Development; World Trade Organization; FAO International Treaty on Plant Genetic Resources; and UN Law of the Seas in addition to the program on “Mangroves for the Future (MFF)” of IUCN and UNDP.

India is strong on the policy front with sufficient legal support for conservation of mangroves; however, effective implementation of such legislations is often hampered by the lack of financial and human resources, poor infrastructure, and lack of political will (DasGupta and Shaw 2013).

3.6.3 Participatory Management of Mangroves

Mangroves are much to be protected with participatory approach from man-made pressures, to encourage resilience to climate change. Of human pressures, two are of great concern: aquaculture and pollution.

Mangrove conversion for aquaculture is a growing threat. In many cases, the aquaculture ponds have been abandoned due to high pollution and shrimp disease issues. It is necessary to find strategies for rehabilitation of the abandoned shrimp forms for restoration of mangroves and other coastal vegetation. Realizing the importance of aquaculture as an important source of livelihood and employment, the Coastal Aquaculture Authority ( 2006) has provided guidelines for the coastal aquaculture practices. It has specifically instructed that mangroves, agricultural lands, salt pan lands, and ecologically sensitive areas, such as sanctuaries and marine parks, should not be used for shrimp farming. A minimum distance of 50–100 meters shall be maintained between the shrimp farm and adjoining land. All shrimp farms should maintain 100 m distance from the nearest drinking water sources. Shrimp farms should be located at least 100 m away from any human settlement in a village of less than 500 populations, and beyond 300 m from any village of over 500 populations, water spread area of a farm shall not exceed 60 percent of the total area of the land. The rest 40 percent could be used appropriately for other purposes like plantation (Coastal Aquaculture Authority 2006).

Despite environmental legislation, water quality continues to degrade due to demographic pressure and rapid industrialization in the coastal areas of India. For instance, the Indian Sundarbans receives a pollution load of as much as 22,900 kg/day (Mandal et al. 2010). Sewage pollution results in eutrophication due to excessive input of nutrients in coastal waters. This affects zooplankton which play a vital role in food chain and fish production. A drastic reduction of zooplankton has been reported in backwaters of coastal Kerala. Any reduction or change in zooplankton biodiversity and biomass will seriously affect the fishery resources of the coastal waters. A continuous monitoring of the surface waters for zooplankton is highly warranted.

A clear framework is required to protect the existing mangroves from the environmental pollution, generated from upstream man-made activities. There is a large marine pollution monitoring program, namely, “Coastal Ocean Monitoring and Prediction System (COMAPS)” with a long-term database being operated by the Ministry of Earth Sciences, Government of India. This program has been operational since 1991. The database generated under the program is hosted by the Indian National Centre for Ocean Information Service (INCOIS), Hyderabad, in its website (www.incois.gov.in) and also in the website of the Integrated Coastal and Marine Area Management Project Directorate (ICMAM-PD) (www.icmam.gov.in). The data facilitates analysis of trends of chemical and biological parameters and reveals effectiveness of pollution control measures initiated by the concerned authorities (Subramanian 2011).

3.6.4 Community Participatory Management

One critical issue is the lack of a participatory approach in management. People realized the importance of conserving mangroves, mostly after the incidence of critical disasters, such as Odisha super-cyclone 1999 and Indian Ocean Tsunami 2004 (Badola and Hussain 2005; Kathiresan and Rajendran 2005; Das 2012). During these events, mangroves not only protected the human life and properties but also less damaged and recovered after the disasters. The people’s perception about the protective role of mangroves during the intense disasters made them to involve actively in mangrove restoration and conservation in the recent years (Badola and Hussain 2005; Gnanappazham and Selvam 2011). Therefore, restoration of the ecosystem services of mangroves with community participation is an important aspect of mangrove management in disaster risk reduction. It is worthwhile to mention here that the Gujarat state government categorized the mangroves, based on their vulnerability to man-made stress, and accordingly management strategies were defined (Pandey and Pandey 2012).

The important aspect of community participation is “Participatory Rural Appraisal,” involving local communities. It involves different steps:

(i) Situation analysis to understand the biophysical conditions and resource utilization pattern

(ii) Selection of villages based on socioeconomic conditions and willingness of local communities to participate

(iii) Critical issues and concerns of the community

(iv) Contact with external institutions for resource and technical advice

(v) Identification of income generation programs, suitable to local conditions to reduce pressure on mangroves

(vi) Formation of village-level institutions, identification of mangrove management units for restoring and conserving the area, village-level microplans for implementing the activities, and implementation, monitoring, and evaluation

It is now mandatory in India that elected panchayats are responsible for disaster preparedness, mitigation, and management. Since mangroves play an important role in disaster risk reduction, the elected panchayats should be actively involved in planning and implementation of mangrove management plans and in raising mangrove plantation in suitable areas that are located outside reserved forest lands. In many states, coastal wetlands that are suitable to raise mangroves are present in large patches, and many of these lands are classified as coastal “proamboke” owned by the revenue department of the state government. These lands can be demarcated and handed over to the elected panchayat to raise mangroves and non-mangrove bioshield.

In India, mangroves are managed prominently in the states of Tamil Nadu, Odisha, Andhra Pradesh, West Bengal, and Gujarat through community-based comanagement (DasGupta and Shaw 2013). The MS Swaminathan Research Foundation and several state forest departments demonstrated a pilot project on the Joint Mangrove Management (JMM). This is a success story in the restoration and conservation of mangroves through people’s participation in India. The JMM project involved 5240 families from 28 villages in three states – Tamil Nadu, Andhra Pradesh, and Odisha along the east coast of India. About 1475 ha of mangroves were restored by planting 6.8 million mangrove saplings, with survival rates between 75 and 80 %. To empower local people, 194 self-help groups were organized to implement poverty alleviation programs such as supplementary income-generating activities for firewood, fodder, fencing, and house construction. Based on this pilot project, comprehensive guidelines for promoting JMM in India have been proposed (Selvam et al. 2001; Ravishankar et al. 2004a, b). In Indian Sundarbans, 65 Joint Forest Management Committees (JFMC) have been formed since 1996, which are playing an important role in mangrove conservation including afforestation of over 17,000 ha of mangroves, management of about 64,000 ha of mangroves, and also saving of tigers (VYAS and Sengupta 2012). The model has also been replicated in other parts of India.

Sundarbans is the most densely populated region of South Asia and the world, with an estimated 4.2 million people directly dependent upon its fragile ecosystem. Most of the people living there are below poverty line, and hence there is overdependence upon natural resources leading to illegal harvesting of productive natural resources within the Sundarbans Biosphere Reserve. This is of great concern with respect to timber products, wildlife, fisheries, protected aquatic species, and shrimp seed harvest. Realizing this critical situation, the State Government of West Bengal created “Sundarbans Development Board” in 1973 and recently upgraded to a separate ministry. Many NGOs and local organizations are also working for awareness raising and capacity building for livelihood in the mangrove areas. These activities include water harvesting structure like irrigation channels, sweet water ponds, and communication system, viz., brick-paved paths and jetties; solar light; medical camps, formation, and strengthening of self-help groups; marketing; etc. The Joint Forest Management Committees are entitled to free non-timber forest produce collection and 25 % share in ecotourism government revenue (VYAS and Sengupta 2012).

Mangroves are used mostly as fodder in Gujarat state. Camel herding is a major activity practiced by the pastoral communities known as “Maldharis” in Gujarat. An in-depth study was carried out by the Gujarat Ecological Commission (GEC) under a mangrove restoration project funded by the India-Canada Environment Facility (ICEF) to understand the Maldharis lives, their dependence on mangroves, and their willingness to participate in mangrove restoration work and also to involve them as stakeholders for the long-term sustainability of the mangroves. The study has revealed that only 21 % have medium to high dependence on mangroves, and this dependence is governed by several factors such as livestock type, availability of alternative fodder, and official access to mangroves. There has not been substantial impact of pastoral activities on the mangrove degradation except Alia bet, in the mouth of Narmada estuary. The degradation and nonaccess of mangroves have critically impacted their livelihoods. Mangrove regeneration should be much practiced at improving the resource availability. The Maldharis must be made real stakeholders and arrangements for benefit sharing need to be worked out.

3.6.5 Livelihood and Income Generation

Community participation for conserving mangrove resources will be successful only when the livelihood and economic benefits are ensured to the mangrove-dependent community.

Fishing in mangroves is the main source of income for coastal people. Mud crabs, oysters, shrimps, and estuarine fishes are largely collected in the mangrove areas. However, depletion of fish stocks affects income generation. Overexploitation of juvenile tiger prawn is a serious problem especially in the Sundarbans, as it affects adversely the fishery resources. To cite an example, in Sundarbans, 540 million tiger prawn juveniles are collected every year by 40,000 fishers, and during this operation, 10.26 billion other fish juveniles are killed. About 48 to 62 species of finfish juveniles are wasted per net per day. Annually a single haul may destroy 1,79,47,050 kg of other fish juveniles! Undersized fishes are harvested and other fishes at their reproductive stages are overfished using nets of small mesh size (Abijit and Kakoli 2005). A variety of molluskan species are sacrificed to obtain shell, from which lime is manufactured.

It is necessary to integrate and promote the mangrove conservation with fishery development. This can be promoted by encouraging traditional canal fishing methods, crab fattening in mangrove waters, and oyster and clam culture. In this regard, the Integrated Mangrove Fishery Farming System, in which mangroves, halophytes, fish, crabs, and shrimps are cultivated in the same farm, is practiced on pilot scale with local communities, government agencies and shrimp farmers. This practice is environment-friendly as it does not involve the use of chemicals and artificial feeds. Up to 35 % of the available space is kept for mangroves and halophytes, and the rest is used to hold seawater for polyculture of several food fishes. These integrated aqua-farming models have a great potential for future as India has about 3.1 million hectares of coastal saline land.

Apart from fishing, developing alternate and supplementary livelihood is the most important aspect to reduce the human pressure on mangrove resources. In the absence of any alternate livelihood, the poor people depend largely on forest resources, and they resort to illegal practices, such as over-fishing, poaching, and felling. It is estimated that in the Sundarbans each year, about 5000 fishermen and 500 honey collectors and woodcutters enter the forests in search of livelihood ignoring even the threat of attacks by tigers and crocodiles! The local people should be trained on alternate and supplement livelihoods to gain employment. Some supplementary livelihoods are apiculture, honey collection, cultivating higher-yielding crop varieties, changing cropping patterns and practices, animal husbandry, ornamental fish culture, seaweed cultivation, microalgal culture, carpet weaving, duck rearing, tailoring, carpet weaving, mushroom cultivation, small cottage industries, and ecotourism. Institutional arrangements have been made by many state governments of India for economic upliftment of the mangrove-dependent communities.

Mangroves are used in indigenous medicine. This traditional knowledge is yet to be scientifically validated. Research studies have proved the mangroves as a source of high-value products, such as black tea, medicines to cure dreadful human diseases like AIDS and cancer, microbial bio-fertilizers, fish feeds, single-cell proteins, pigments, nanoparticles, and microbial enzymes of industrial utility (Kathiresan and Qasim 2005). Further studies on these aspects will prove a greater efficacy of the mangroves in clinical medicines and for other useful products. Bioprospecting of mangrove ecosystems may lead to development of patents, which in the future can be a source of revenue and employment opportunities.

3.6.6 Identification and Protection of Vulnerable Mangrove Sites

Table 3.3 depicts about intensity of vulnerability and factors of vulnerability and resistance/resilience to climate change in different states and union territories of India. To mitigate the risk of losing mangroves to sea level rise, it is necessary to identify and protect mangrove areas, vulnerable to sea level rise. Such areas can be identified based on their location in the areas with small islands, lack of rivers, sediment-starved, micro-tidal, less availability of freshwater, high salinity, groundwater extraction, coastal development, underground mining, carbonate settings, tectonic movements, and steep topography.

Table 3.3 Mangroves in different states and union territories of India and their types, intensity of vulnerability, and factors of vulnerability and resistance/resilience to climate change
Full size table

Mangrove areas less vulnerable to sea level rise can be identified locally based on the presence of sediment-rich, macro-tidal environments and the availability of freshwater to reduce increasing salinity. The mangrove species can be identified based on their potential of migrating to landward in response to sea level rise. The mangrove habitats with abundant mature trees producing a healthy supply of seeds and propagules, along with dense epibiont communities, such as oysters should be protected. This may serve as sources for colonizing new areas and repopulating areas damaged by disturbance. Such mangrove areas should be protected under “marine and coastal protected areas” or incorporated into integrated coastal management programs. Currently, there are 31 marine and coastal protected areas in India under the Wildlife Protection Act, 1972, most of which includes mangrove forest habitats.

Generally, mangroves produce abundant seeds and seedlings, but their dispersal, survival, and establishment are of serious concern. Therefore, it is necessary to assess natural regeneration for its constraints and to implement correction measures for facilitating the dispersal and establishment of mangrove propagules.

Mangrove lands are privately owned in many areas especially in the states of Kerala, Karnataka, Andhra Pradesh, and Maharashtra. A high rate of human population growth has resulted in acute land scarcity that led to widespread reclamation of mangrove wetlands, which has resulted in significant loss of mangroves. It is necessary to develop suitable mechanisms to manage the mangroves of private ownership.

3.6.7 Restoration of Degraded Areas

Mangroves enhance fisheries, forestry production, and coastal protection against natural disasters (Hiraishi and Harada 2003; Kathiresan and Rajendran 2005; Danielsen et al. 2005; Saudamini Das 2004). However, mangrove areas are shrinking in many places along the coastal India. The main reasons for the mangrove shrinkage is high salinity due to improper fluxing of tidal and freshwater, as well as conversion of mangroves into shrimp ponds. Therefore, mangrove restoration is practiced to increase the mangrove area by replanting mangroves in the areas where they previously existed. This also helps in maintenance and enhancement of biological diversity, rehabilitation of endangered and endemic species, and fishery development without mangrove destruction. Restoration of degraded areas is practiced by (i) hydrological manipulation through construction of creeks, thereby flushing the degraded areas with tidal waters; (ii) community participation; and (iii) integrated farming practices. Over the last decade, the mangrove restoration gained momentum all across the major mangrove areas in India (Bhatt and Kathiresan 2012; VYAS and Sengupta 2012). The mangrove restoration is an economically appropriate option, and it should protect people from future events of natural disasters.

The areas planted with multiple species of mangroves have greater ecological resilience. Unfortunately in plantation program, only few species of fast-growing mangroves such as Avicennia and Rhizophora are used. This results in mangrove areas of low diversity and they are likely to be vulnerable to disasters.

3.6.8 Coastal Shelterbelts Plantations

Coastal shelterbelts are an important option for disaster risk reduction. The coastal shelterbelt plantations are made with Casuarina sp., palmyra palm, and other beach vegetation including sand dune vegetation with appropriate width and density. Coastal shelterbelt with less than 200 m wide was not found to be very effective against the 2004 tsunami. Such coastal shelterbelts have been conserved and raised in the southern states of India, viz., Odisha, Andhra Pradesh, Tamil Nadu, Kerala, and Karnataka. Tamil Nadu alone has developed extensive Casuarina plantations covering an area of 7549 hectares along the coastline. However, multiple species plantations provide better protection than monoculture plantations (VYAS 2012). The coastal shelterbelts are beneficial to protect mangroves from human interference and also to local community in raising their socioeconomic levels in addition to protecting them against cyclones and storm surges.

3.6.9 Adaptation to Climate Change

People, dependent on mangroves and coastal fishery resources, have to cope up with climate change. A considerable number of nongovernmental organizations in particular the MS Swaminathan Research Foundation, Worldwide Fund for Nature (WWF), Wild Life Protection Society of India (WLPSI), and Mangrove for Future (MFF) are working for raising awareness and capacity building of people on adaptation to climate change.

Small-scale fisheries will be the most vulnerable to climate change as the adaptive capacity of the fisheries is low. It is necessary to reduce the vulnerability to climate-related impacts. In this regard, most effective actions are required to deal with over-fishing and adoption of Code of Conduct for Responsible Fisheries and Integrated Ecosystem-based Fisheries Management. Another important way of mitigating impacts of climate change is to reduce the fishing mortality in fisheries. The targeted fishing for shrimps and lobsters for export market is responsible for discarding the bulk of the other catches as discards or trash fishes. Total discards of trash fishes may be in excess of 1,000,000 tonnes per annum in India (Pramod 2010). It is necessary to develop projections of climate change on fish distribution and abundance catches for planning better management adaptations.

Vivekanandan (2011) suggested some measures to coping with climate change:

(i) Evaluating the adaptive capacity of important fish groups

(ii) Identifying adaptive fishing and postharvest practices to sustain fish production and quality

(iii) Supporting energy-efficient fishing craft and gear

(iv) Cultivating aquatic algae, which have positive response to climate change for food and pharmaceutical purposes and for production of biodiesel

(v) Increasing climate literacy among the fishing and farming communities

(vi) Establishing weather watch groups

(vii) Establishing effective coast protection structures including mangroves

3.6.10 Baseline Data Development

Baseline data development is a matter of necessity toward disaster risk reduction and climate change adaptation for mangroves. In India, GIS-based atlas for mangroves has been prepared about mangrove resources and utilization as well anthropogenic pressure. This is helpful to develop mangrove management plans in particular for the east coast of India. This is the first successful step to understand the status of mangrove conservation and management in India. Further, it is necessary to prepare a state-wise database on mangrove ecosystems of the country to provide data on the status of flora and fauna including endemic species, exotic species, their vulnerability to climate change, bioprospecting potential, and possible conservation measures through ex situ and in situ methods. It is required to establish baseline data on forestry structure, species richness, abundance and diversity of flora and fauna, primary production, and nutrients and hydrological aspects for monitoring the response of mangroves to climate change. Such baseline data based on scientific studies are required for proper conservation and management of mangroves against risk reduction. In this regard, the Ministry of Environment, Forests and Climate Change, Government of India, is preparing the database for mangroves and other coastal ecosystems, through the Environmental Information System (ENVIS) Centres and National Centre for Sustainable Coastal Management.

3.7 Concluding Remarks

Mangroves are extraordinary ecosystems, providing many goods and services including their role of disaster risk reduction and climate change adaptation. India has a total area of 4740 sq. km under mangroves. There are only 39 core mangrove species in India which support 3972 other biological species.

The mangroves exhibit resistance and resilience to overcome potential impacts of climate change. However, the mangroves may be vulnerable to sea level rise, and the extent and composition of mangroves may undergo changes. In general, the mangroves along the east coast of India may be vulnerable to sea level rise, more than the west coast of India. The mangroves of Sundarbans and Gujarat are comparatively less vulnerable to sea level rise than all other mangroves of India, especially those in Tamil Nadu and Kerala, which are also low-lying coastal areas.

India has varied role to play in promotary, regulatory, and participatory management of mangroves to mitigate the impacts of climate change. Under the promotary management, the government is managing the mangroves efficiently in 38 selected areas along the Indian coastline, in spite of the growing threats by humans and natural calamities. Under the regulatory management, the mangroves are well protected by strong legal frameworks in the national park or wildlife sanctuary or reserve and protected forests and/or community reserves. Regarding participatory management, Indian mangroves especially in Tamil Nadu, Odisha, West Bengal, and Gujarat are managed through community participation. What is much required for the future of mangroves in India is restoration of ecosystem services of the mangrove areas, vulnerable to climate change, with community participation, assisted with infrastructure development, financial support, and strong political will.