Impact of Climate Change and Ongoing Adaptation Measures in the Bangladesh Sundarbans

The climate of Bangladesh has changed drastically which may put considerable adverse impacts on mangrove fishers but very few studies focused on this professional group. An attempt was made to perceive the impact and adaptation measures of the Sundarbans mangrove resource users, employing interviews and focus group discussions. A total of 150 respondents were randomly selected from the Sundarbans west under Shyamnagar Upazila of Satkhira District. It was revealed that the abundance of fishes, fuel woods, honey, golpata (Nypa fruticans), and shrimp post-larvae (PL) was reduced considerably. The resource users have adapted themselves by changing their occupation and becoming jobless and depending on the other family members. PL collection, honey collection, shrimp culture, and wood collection were found professional adapting strategies to adopt cyclone, flood, salinity intrusion, river erosion, and drought. Several recommendations are elicited, the implementation of which is important to ensure livelihood sustainability of the mangrove communities.


Introduction
The Sundarbans is a part of the world's largest delta formed by the rivers the Ganges, Brahmaputra, and Meghna, covers about 4.2% of the total Bangladesh where forests cover only 10.2% of the land area 1,2 . It is the largest single block of tidal halophytic mangrove forest in the world 1,2 which is situated in the South-West area (21º 31′-22º 38′N and 89 º 00′-89º55′ E) of Bangladesh and has been a Ramsar site from 1992, world heritage of UNESCO from 1997 2,3 .
It has covered approximately 10,000 km 2 , among which 60 percent remain in Bangladesh and the rest of the part remain in India 4,5 . The Sundarbans covers approximately 6,017 km 2 area in Bangladesh, where 4143 km 2 area is landmass and remaining 1874 km 2 area are water bodies in forms of a network of rivers, canals, and creeks 6 . Sathkhira, Khulna, and Bagherhat districts cover approximately 99% of the Sundarbans in our country and the remaining areas are in Patuakhali and Barguna districts 7 . Three types of ecosystem services are primarily derived from the Sundarbans of Bangladesh. These include provisioning services (benefits that people obtain directly, e.g., timber and food products such as fish), cultural services (non-material benefits, e.g., mangrove tourism), and regulatory services (benefits obtained from the regulation of ecosystem processes, e.g., carbon sequestration and protection from cyclones) 2 . The Sundarbans mangrove forest is rich with its natural floral and faunal diversity like 334 species of plants, 425 species of wildlife; including 40 species of mammals, 300 species of birds and 35 species of reptiles, 177 species of fish, 24 species of shrimp, and 7 species of crabs, etc. 2,6,8 . About 5 million people are engaged directly and indirectly which are depending on the Sundarbans for their livelihoods where 69% are involved with the aquatic resources, 22% people are with the collection of wood resources; 5% are involved with the non-timber forest product, and 4% are involved with other purposes 9 .
The Sunderbans provides a wonderful aesthetic attraction for local and foreign tourists. The vegetated tidal lands of the Sundarbans also function as an essential habitat, produce nutrients, and purifies water. The forest also traps nutrients and sediment, acts as a storm barrier, shore stabilizer, and energy storage unit. Mangrove wetlands act as a barrier against natural climates, avoid coastal erosion and provide nursery grounds for a number of commercially important fish, prawns, and crabs. Some of these mangrove wetlands play an important role in enhancing the fishery production of the adjacent neritic waters by exporting organic and inorganic nutrients 10 . The environmental setting of this multiple-use ecosystem is governed by physical forces such as geomorphology of the coast, climate, tidal amplitude and duration, and quantity of freshwater inflow [11][12][13][14] .
Categorized as "Reserved Forest" the Sundarbans is very important for being the source of forestry products and fish that enrich the local and national economy, as well as for being the protector from the heavy ravages of periodical cyclones and tidal surges originating from the sea [15][16][17] . At present four major types of livelihood activities are practiced in the coastal areas including mangrove forests this are agriculture, fishery, wood collection, and honey collection [18][19][20] .
Approximately 65% of the total population is dependent on agriculture-based economy. Fishing activities are prevalent at various scales in the Sundarbans catering to livelihoods amongst 15% of the population. Organized large scale fishing activity occurs in the sea and deep water and small scale fishing activity in the delta region (half of them are illegal) [21][22][23][24] . Microscale fishing activity in the shallow river bed is operated mainly to collect the prawns/shrimps post-larvae [25][26][27][28] .
Climate change due to global warming is predicted to cause an annual temperature rise of 0.4 degrees celsius in Bangladesh and resulting in sea level is also predicted to rise by 4 millimeters every year 2,16,[29][30][31] . These phenomena will result in an increase in salinity and a decrease in the sweet water flow in the Sundarbans and hence will destroy major forest resources [32][33][34] . Climate change creates resource shortages and unreliable job markets that lead to the increased migration [35][36][37] . Several studies have been conducted on Sundarbans mangrove forest but the limited study has been conducted on the climate change impact of Sundarbans. Considering the above factors, therefore the present study has been conducted to identify the impact of climate change on the Sundarbans mangrove forest and adaptation measures taken by resource users of Sundarbans.

Methodology
The study area covered Sundarbans west in Shyamnagar Upazila of Satkhira district. The study was conducted for a period of nine (9) months from July 2017 to March 2018. There were a total of 150 respondents from different socio-economic and operational groups (fishermen, honey collectors, golpata collectors, wood-cutter, and resource harvesters). As a method of carrying out a successful interview, the respondents were interviewed with semi-structured questionnaires designed for these purposes. The purpose of the survey was to gather information related to demography (e.g., basic information of community), depression and cyclones (duration, types of disaster, frequency/wind speed, storm surge height, and casualty), and mortality rate. The survey method was followed for collecting both quantitative and qualitative primary data from each spot using a well defines and pre-tested questionnaire following the objectives set for the study.

Climate changing hazards
The respondents were interviewed to know about 30 year's climate-changing hazards which were shown in Figure 2. Respondents have faced cyclone (34%), flood (6%), drought (1%), river erosion (2%), salinity intrusion (5%), and 52% faced multiple hazards (such as cyclone, flood, salinity intrusion etc.). The majority of them had been faced cyclones, floods, salinity intrusion, drought, river erosion etc. A study revealed that most of the respondents had faced tidal surges, floods, and cyclones (91.67%, 66.67%, and 50%, respectively). River erosion, tsunami, and excessive rainfall were the other disasters faced by the respondents. The natural disaster was the constant company of the coastal population. They were faced more than one disaster every year 21,37 . The disaster was considered to be a great constraint for sustainable development in Bangladesh. Cyclone, tidal surge, flood, river bank erosion were some of the worst types of the disaster which was badly affecting the livelihood of our people especially in the coastal zone 22,38 . Coastal areas put the coastal peoples at high risks as these areas were susceptible to numerous natural hazards, such as cyclones, tidal surges, salinity intrusion, riverbank erosion, shoreline recession, tsunami etc 39 . The risks from tropical cyclones, storm surges, floods, and other climatic hazards are geographically concentrated in specific regions of the Sundarban 25,37 .

Devastating natural disasters
The frequent occurrence of extreme events such as cyclones, strong wind, and wave, current and Mahasen in 2013 and Gorki in 2016 that put adverse impact on the communities by destroying their residence and fishing utensils and allured to illegal fishing to compensate the loss 37,38 .
The disasters which affected mostly were represented in Table 1

Damages of natural disasters
The present study found that respondents experienced the death of people (2%), house damage and death of domestic animals (35%), damage of crop (15%), damages of fisheries (23%), death of man, animal, and house damage (13%), and (12%) was damage of fish and crops ( Figure 3).
Natural disasters drastically destroyed houses, trees, roads, dams, causing the death of man, animals, birds, and damaged fish farms, croplands.
Koyra, Dacope, and Shymnagar Upazila of the south-west coastal belt of Bangladesh were hit the hardest by the cyclone Aila. The storm surge washed away all the houses, crops and agricultural land, homestead garden, and livestock, and thereby the area experienced huge toll damages to lives and livelihoods. Aila not only broke down the overall social harmonization but also resulted in a chaotic situation in those areas. One-fourth of the Sundarbans forest area had been damaged by the cyclone Sidr 2,26,38 . Precisely eight to ten percent of the forest had been damaged completely, while fifteen percent has been partly damaged.

Resources of the Sundarbans before frequent occurrence of natural calamities
In the present study, it was found that 34% of resource users remarked plenty of fish, crab, and shrimp, 21% remarked plenty of fruits, 12% remarked plenty of livestock and wild animals, 4% remarked plenty of river and canal, 11% remarked availability of honey and wax, and 18% remarked plenty of golpata ( Figure 4). Sundarbans, the largest mangrove forest was teeming with natural resources and were served as a diverse habitat for many species, including fish, birds, reptiles, amphibians, mollusks, crustaceans, and many other invertebrates. It was full of Sundari trees (Heritiera fomes). The leaves of golpata (Nipa fruticans) were harvested by the local community for thatching purposes. Mangroves were a good source of wood, timber, and housing

Resources of the Sundarbans after frequent occurrence of natural calamities
The resource users remarked that inadequacy of fish, crab, and shrimp (29%), scarcity of wooden tree (23%), scarcity of animals (13%), reduction of honey and wax (9%), and 26% found scarcity of golpata ( Figure 5). Climate change reduced the stock of resources. Saline water increased with the sea level rising, as a result, freshwater fishes losses their habitat. One calculation showed that a 25 cm sea level rise would result in a 40 % mangrove loss 28 . The local community remarked that excessive heat reduced the water retention capacity of the land, trees have died lack of water. The rain did not come in timely so animals, fishes cannot breed, as result fishes were decreasing day by day. The tree couldn't survive due to lack of rainfall, excess salinity, the heat so honey was decreasing day by day. River, canals were losing depth due to siltation, as a result, breeding and feeding ground was hampered. The prevalence of higher poverty in these areas might also be connected to poor livelihood patterns alongside higher environmental adversity. Livelihoods in these areas were mainly based on local resources (e.g. forest) and their extraction (e.g. agriculture, fishing) 29 .

Impact of climate change on water body
Most of the people (37%) cited that scarcity of fish, 37% opined siltation, and 17% mentioned the increase of salinity and 9% reported reduction of current as of the climate change impact ( Figure   6). Rivers, canals, swamps lost their flow, and day by day fish and other aquatic animals lost their number and abundance significantly. Saline water entered into the freshwater canals. Siltation was a great problem for rivers, canals, swamps which caused floods during the rainy season. Flowing water in the rivers, canals, etc. through and around the Sundarbans flushed out saline water intrusion from the sea. Increasing salinity intrusion due to anticipated sea-level rise was one of the major threats to the Sundari trees, which were already under threat due to increased salinity levels 30 .

Climate change impact in Agriculture
The study showed that 38% of people said reduced yield than before, 33% people said that agricultural crops are more affected by disease and 29% said that increased soil salinity (Figure 7) . At present, salinity in river water had exacerbated the inundation problems from Cyclone Aila.
The tidal surge during the cyclone rushed over or broke rivers' embankments and covered farmland in saline water. This means that even after the water had subsided and the land was dry, salinity will continue to harm crop cultivation, grazing, tree growth, etc. for years 31,40 . Agricultural crops were attacked by disease, pesticides, and insecticide used at high doges to prevent disease, these chemicals mixed with water and polluted the water body.

Climate change impact in fisheries
The present study mentioned that, 32% of people mentioned that less production, 28% cited that affected by the disease, 24% told damage of fish farm, 9% said that loss of breeding ground and

Status of fisherman of Sundarban
The Sundarban dependent fishermen were decreasing (57%), some were newly added that counted as the increase of fishermen (27%) and 16% remained unchanged (Figure 9). Fish availability reduced significantly due to climate change as a result fishers were decreasing day by day.
Vulnerability due to climate change was influenced by the status of the community and its

Effect of climate change on salinity intrusion
Among the interviewed respondents 38% said that damage of water source, 33% said that damage of cultivated land, and 29% said that losses of freshwater fishes due to salinity intrusion ( Figure   10)

Occupational changes of resource users
It was found that 14% of fishermen changed their occupation and 30% fishermen remain unchanged, 6% honey collector changed their occupation and 21% remain unchanged, 15% PL (Post-larvae) collectors changed their occupation and 20% remain unchanged, 6% golpata collector changed their occupation and 13% remain unchanged, 3% woodcutters changed their occupation and 17% remain unchanged their occupation ( Figure 11). Now, 7% respondents changed to the brick worker, 10% changed to day labor, 6% became motorcycle driver, 4% changed to construction worker, 4% became carpenter, 5% changed to patty businessman, 5% become building maker, 3% become fish farmer, 5% become unemployed and 101% remain unchanged. Mangrove resource users changed their occupations on a large scale. Some remained unchanged. Besides these, some were newly added. The mangrove forests have been shown to sustain more than 70 direct human activities, ranging from fuel-wood collection to fisheries 36 . Fig.11. Occupational changes of resource users.

Adaptation of Sundarban resource users
The study found 29% of people change their occupation to adopt the professional loss in changing climate ( Figure 12). About 3% of people mentioned that their family members migrate towards town, 10% people tried to practice climate resilience culture techniques of rice, fish, and crops.
About 7% of women have participated in work, homestead gardening 4%, and salt cultivation 3%.
Traditional lifestyles were reasonably well adapted to these unique characteristics of the Sundarbans. Human dwellings were built on raised platforms, and farmers cultivated salinity and flood-tolerant rice during the monsoon in land protected by temporary dykes when the abundance of freshwater had greatly reduced salinity levels 17,37,42 .
The dykes were dismantled post-harvest, opening the land to tidal movements. Meanwhile, fishing of salt-tolerant varieties was the principal source of livelihood during the dry season when salinity levels were high. People also cultivating betel leaf as their cash crop and it was profitable. But the betel vines were very much vulnerable to flood and storm. Due to climate change, betel leaves were affected by diseases and pests. So, farmers fall into danger and became looser. Women were aware of the fact that a certain species grow well in saline conditions. They planted palm, betel nut, sofada, etc. sapling which provided little cash for the family. Women also engaged themselves in handicraft, based on their individual skill. It was found that 36% of peoples took adaptation measures to cope with cyclone, 33.3% with a flood, 2% with drought, 11.3% with river erosion, and 17.4% with salinity intrusion. Flood resilient housing, raising plinth of the house was done by the flood-prone people to adapt against flood. Farmers produce saline tolerant rice such as BARI dhan 40,41, BINA Dhan 7.Chilis, Carrot, Sugar beet, Barley were also cultivated by the resource users as alternative cultivation 26 .

Conclusion and recommendations
Sundarbans is one of the largest mangrove forests in the world. The Sundarbans has great importance in the economy of Bangladesh but frequent occurrence of natural calamities put adverse impact on its natural resources and day-to-day life of the dependent communities. Day by day sea level raises gradually and salinity increases rapidly, as a result, cropping pattern, methods  Awareness on climate change should be increased among the resource users by enhancing coordination between private and public organizations.
 Expansion of indigenous knowledge on adaptation among the climate-vulnerable communities.
 More pragmatic participation of GO's and NGO's in disaster-prone area should be ensured.
 The social security of local people should be strengthened.
 The sustainable harvest of resources should be monitored.
 More cyclone shelters, medical centers, embankments should be constructed for the security of the local people.
 Ban of Pl collection and alternative livelihood programs should be introduced.