“The health of humans has always depended on the health of the planet, but in today’s changing world, the importance of mangrove ecosystems is all too clear. Yet it is estimated that some countries lost more than 40 per cent of their mangroves between 1980 and 2005, often due to coastal development.”
–Audrey Azoulay, UNESCO Director-General
Mangrove species are unique, resistant shrubs or trees growing in coastal saline water or brackish water. These trees show high-level adaptations to thrive in harsh coastal environments with saturated saline water. Mangroves acquire a complex salt filtration system and a complex root system to cope with saltwater immersion and wave action. Thus, they are able to thrive well even in low oxygen conditions. Mangrove vegetation form rare, spectacular and prolific ecosystems on the boundary between land and sea, which are quintessential for the environmental wellbeing, food security, and biodiversity. Mangroves are also important for the protection of the coastal communities since they function as coastal defence against storm surges, tsunamis, rising sea levels, and even erosion.
The case of Kapuhenwala and Wanduruppa, two villages in the lagoon of southern Sri Lanka, is a classic example to highlight the significance of mangroves in protecting the coastal population; during the 2004 tsunami that occurred in the Indian Ocean, causing massive destruction of both lives and property in Sri Lanka, the two villages, closely located, experienced the tsunami waves in different ways. In Kapuhenwala, surrounded by 200 hectares of dense mangroves and scrub forest, the tsunami killed only two people-the lowest number of tsunami related fatalities in a Sri Lankan village, while Wanduruppa, surrounded by degraded mangroves was severely affected causing 5,000 to 6,000 deaths. Mangroves have been calculated to be capable of absorbing 70 – 90 per cent of the energy of a normal tidal wave.
Mangrove forests represent only less than 1 per cent of the total tropical forest cover and even lesser percentage of the total forest estate – less than 0.4 per cent. Therefore, it is climacteric that these mangroves are properly protected. Nonetheless, what happens now is the opposite of it. The mangrove vegetation is being depleted at a fast rate due to numerous ecological and socioeconomic factors. Current estimates indicate that the coverage has been halved in the past 40 years. According to Global Mangrove Alliance, an estimated 67 per cent of mangroves have been lost or degraded to date, and an additional 1 per cent is lost annually.
World Mangrove Day
Having considered the urging need to conserve the mangroves worldwide, the United Nations Educational, Scientific and Cultural Organisation (UNESCO) has declared the World Mangrove Day which is officially known as International Day for the Conservation of the Mangrove Ecosystem, and 26 July was officially declared as the International Day of the Conservation of the Mangrove Ecosystem, through the resolution 38C/66 by UNESCO, in response to the request of Ecuador, on 6 November 2015, at its 38th session of the General Conference in Paris. The date has been chosen to commemorate Greenpeace activist Hayhow Daniel Nanoto, who died of a heart attack on 26 July 1998 during a massive protest aiming to re-establish the mangrove wetlands in Muisne, Ecuador. Since then, the World Mangrove Day is observed each year on 26 July with the aims to, “Raise awareness of the importance of mangrove ecosystems as a unique, special and vulnerable ecosystem and to promote solutions for their sustainable management, conservation and uses.”
Mangroves in Sri Lanka
Typically, the width of the mangrove forest cover relies on tidal amplitude and in Sri Lanka where the tidal amplitude tend to be very low (75 cm), mangroves are typically constrained to as an alternative narrow belts which cover only about 0.1 – 0.2 per cent of the island’s total land area. The main mangroves in Sri Lanka are deciphered to be located in the vicinity of Jaffna, Wadamarchchi, Thondaimanar lagoons (North Coast) Kokkilai, Navarau, Lagoons, Trincomalee, Kathiraveli, Valaichcenai, Batticaloa, Pottuvil (East Coast) Weligama, Gintota (South Coast) Balapitiya,Bentota, Negombo and Chillaw lagoons, Puttalam, and Mannar lagoon (Western and Northwest coast). Mangroves in Sri Lanka have been discontinuously distributed along coasts around lagoons, bays, and estuaries with an area of 8 000 – 7 000 hectares. However, an estimate done in 2010 has demonstrated that the extent of mangroves in Sri Lanka is about 15,670 hectares.
Although there are several records of the mangrove species available in Sri Lanka, it is commonly accepted that there are 21 identified species in the coastal areas of the country. Mangroves are categorised into two; as ‘’true mangroves’ or ‘obligate mangroves’ and as ‘mangrove associates’’ or ‘semi-mangroves’. True mangroves habitat best in mangrove forests and are not discovered in terrestrial communities. They additionally morphologically specialised to the mangrove environment and undergo specialised morphological diversifications such as aerial roots, buttresses, salt-excretion thru leaves, buoyant, and viviparous propagules.
The most common and widely distributed true mangroves species are Avicennia marina (Api-api Jambu), Rhizophora mucornata (Loop-root Mangrove, Red Mangrove or Asiatic Mangrove), Rhizophora apiculata, Bruguiera gymnorhiza (Large-leafed Orange Mangrove), Bruguiera sexangula (Upriver Orange Mangrove), Excoecaria agallocha (Blind-your-eye Mangrove), Sonneratia caseolaris (Mangrove Apple), Aegiceras corniculatum (Black Mangrove), and Lumnitzera racemosa (White-flowered Black Mangrove).
A Significant fraction of the Sri Lankan ecosystem
Speaking to Ceylon Today, Professor in Oceanography, Department of Oceanography and Marine Geology, University of Ruhuna, Dr. Terney Pradeep Kumara, explained the importance of mangroves in Sri Lanka in several crucial ways.
“They are the main filters of the coastal belt. The mangroves function with their filtering abilities to filter whatever comes with water, let it be pollutants or sediments, and only the filtrate is sent back to the sea. Whilst the filtration processes, the mangroves also absorb the nutrients present in water and feed upon them. If this process stops, all the pollutants, sediments, garbage and nutrients also would directly flow to the sea and deposit on the seabed. Then, the sea grass and algae would feed upon them and, due to their rapid growth rate, would soon over grow the corals. This makes it susceptible for various diseases and even blockages in water ways. So, eventually it would cause ocean and coastal pollution.” He shared how mangroves contribute for the equilibrium of the coastal environment in a very subtle manner.
Synonymously, Dr. Kumara elucidated how the mangrove vegetation purifies the atmosphere by fixing carbon. Mangrove forests are enormously effective as they allocate proportionally greater carbon belowground, and have higher below to above-ground carbon mass ratios than terrestrial trees. Maximum mangrove carbon is saved as large pools in soil and lifeless roots. They are one of the most carbon-rich biomes, facilitating the build-up of fine debris, and fostering fast rates of sediment accretion and carbon burial. Mangroves account for best approximately 1 per cent of carbon sequestration by using the world’s forests; however as coastal habitats they account for 14 per cent of carbon sequestration by means of the worldwide ocean. If mangrove carbon shares are disturbed, resultant gas emissions can be very high. So, in a way, mangroves are highly accountable for keeping the global warming low. “At the same time, they function as food producers in the coastal environment and ergo, initiate food chains and webs,” he furthered.
“Next, Mangroves provide a great habitat for many water dwelling animals as well as for several bird species adapted to the coastal environment,” spoke Dr. Kumara. “The well-developed root systems of mangroves function as nursery grounds not only for marine species of fish and shellfish but also for some freshwater species such as genus freshwater shrimps or prawns, crabs and snails. So we can see a highly diversified bio-system there. It contributes for tourism, bio diversity and food security as well”.
The advantages of mangroves do not limit to those aspects, but they directly facilitate human activity in other ways also. Dr. Kumara mentioned that mangroves provide food for the coastal communities and thus ensures the food security. “Kirala is a classic example. Various foods are made with the fruit of Kirala trees. Kirala juice is such very delicious and nutritional beverage.”
Mangrove wood is a fine fuel used basically food preparation at domestic level. “Add to that, different parts of the mangrove trees are utilised in making equipment needed for the fishing industry,” he stated.
Threats and conservation
Mangrove vegetation is threatened due to various socio-economical and anthropogenic factors, both locally and globally and it has had a toll on global warming and biodiversity. Answering to our question, Dr. Kumara spoke about the threats faced by the mangrove vegetation, particularly in Sri Lanka.
“Mangroves are basically threatened by development projects and construction activities. The vegetation used to be cut at large scales for development projects. Improper constructions are another issue. Sometimes people fill up mangrove growing lands with garbage, and then cover it with a layer of soil and use for constructions and private lands. Also, when some constructions are done, they knowingly or unknowingly block the natural water ways that flows into the brackish water bodies where mangroves grow. Thus, they eventually dry up and the vegetation withers,” he briefed.
On a minor scale, mangroves are cut for domestic activities also. It could be prevented through public awareness. Also, there is some destruction going-on in mangrove ecosystems due to tourism activities centred on them, which is sometimes excessive for the sensitive mangrove vegetation. Thus there should be proper regulatory systems to control the tourist activity around sensitive environment zones.
Ceylon Today reached out to well-known lawyer, environmentalist, Dr. Gunawardana to get an idea about the laws and regulations that are designed to protect mangroves in Sri Lanka. As he explained, mangroves are protected under different enactments in Sri Lanka. When it comes to mangrove species, several species such as Rathambilla and Ginpol, are especially protected under the fauna and flora protection ordinance under section
“Nonetheless, most of the mangrove vegetation is protected under fauna and flora protection ordinance as habitats; either as national reserves (nature reserves, national parks and marine national parks) or sanctuaries. So, mangroves are protected under the forest ordinance as well. In addition, mangroves, which are not been protected under any other ordinance, are protected under the forest ordinance and forest conservation ordinance as ‘other state forests’. So, all mangrove habitats are virtually protected by the law in Sri Lanka,” He furthered.
Dr. Gunawardana moreover explained that if any destruction to the mangrove vegetation is observed, it can be complained to the Divisional secretary, Forest Department or Police. “If the land is protected under the national fauna and flora protection ordinance, Wild Life Conservation Department, can also take legal action against any misuse or harm done.”
By Induwara Athapattu