Sundarbans Area Research Articles

Spatial–temporal changes of shoreline and Vegetation: Impacts on mangrove cover along the Sundarbans area, Bangladesh

Spatial–temporal changes of shoreline and Vegetation: Impacts on mangrove cover along the Sundarbans area, Bangladesh

Sustainable tourism development in Bangladesh: Challenges and opportunities to promote the Sundarbans

Purpose: The main objective of this study is to determine what needs to be managed and what obstacles make this World Heritage Site more attractive to tourists through sustainable development. Research Methodology: The study was mainly quantitative in nature. To acquire primary data, the upazilas of Koira and Dumuria in the Khulna district, as well as Shyamnagar, Debhata, and Tala in the Satkhira district, were conveniently sampled because a sizable portion of Sundarbans are located there. A total of 365 individuals from five preselected locations completed a standardized questionnaire to provide information, and respondents were selected using a simple random sampling procedure. Statistics, such as frequency and percentage, and the logistic regression (LR) model were used to examine the data. Results: Among the independent variables included in the NES framework, only eight variables—advantages of natural diversity, natural complications, compatibility, multi-culture opportunity, diversity of life, job opportunity, GDP contribution, and income opportunity—significantly influenced the sustainable development of tourism in the Sundarbans area. Limitations: This research is based on the selected sample about the sustainability, protection, and promotion of Sundarbans, but most of the respondents had limited ideas about these key issues. Contributions: If a sustainable communication system and a standard resort or hotel-motel are built, domestic and foreign tourists will be interested. Additionally, specific policies and adequate security arrangements should be implemented. Above all, the concerned ministries of the government should come forward to create awareness among the people living in the Sundarban area to protect the natural diversity of the region.

Sustainable tourism development in Bangladesh: Challenges and opportunities to promote the Sundarbans

Purpose: The main objective of this study is to determine what needs to be managed and what obstacles make this World Heritage Site more attractive to tourists through sustainable development. Research Methodology: The study was mainly quantitative in nature. To acquire primary data, the upazilas of Koira and Dumuria in the Khulna district, as well as Shyamnagar, Debhata, and Tala in the Satkhira district, were conveniently sampled because a sizable portion of Sundarbans are located there. A total of 365 individuals from five preselected locations completed a standardized questionnaire to provide information, and respondents were selected using a simple random sampling procedure. Statistics, such as frequency and percentage, and the logistic regression (LR) model were used to examine the data. Results: Among the independent variables included in the NES framework, only eight variables—advantages of natural diversity, natural complications, compatibility, multi-culture opportunity, diversity of life, job opportunity, GDP contribution, and income opportunity—significantly influenced the sustainable development of tourism in the Sundarbans area. Limitations: This research is based on the selected sample about the sustainability, protection, and promotion of Sundarbans, but most of the respondents had limited ideas about these key issues. Contributions: If a sustainable communication system and a standard resort or hotel-motel are built, domestic and foreign tourists will be interested. Additionally, specific policies and adequate security arrangements should be implemented. Above all, the concerned ministries of the government should come forward to create awareness among the people living in the Sundarban area to protect the natural diversity of the region.

Some Aspects of Fish Marketing in Shyamnagar (Sundarbans Area) Bangladesh

The current study is focused on Sundarbans's fish marketing aspects, taking into account some inefficiencies, economic characteristics of marketing activities, and existing marketing systems. In Shyamnagar, a huge number of people depend on fish distribution and marketing networks for their livelihoods. Fish marketing is virtually entirely a private sector domain. Local merchants, agents/suppliers, wholesalers, and retailers are just a few of the intermediaries in the market chains that connect producers with the consumers. The daily supply of fish at the Shyamnagar upazila fish Market, kalbari fish market and Nwabeki fish market in Shyamnagar was estimated to be 15-16, 18–19 and 12–13 tons, respectively, based on a sample of 60 dealers from the three major markets in the upazila. Almost all of the fish (80%) is imported from Sundarbans and the surrounding areas and just 20% of the seafood is produced locally. According to estimates, carps make up 40% of the fish sold in marketplaces. 13% hilsa, 10% catfish, 7% native small fish, 10% prawns and shrimp, 7% tilapia, and 13% other species, including small chingri (shrimp) are the other aspects. Fish prices are influenced by market dynamics, species quality, size, and weight; it has been discovered that the cost per kilogram of carp rises with size. In three markets, every trader generated a sizable profit.

Rising trend of man-tiger conflict at man-nature interface of Indian Sundarbans: study towards traditional understanding and challenging livelihood of Sundarbans people

Sundarbans region has its own unique physiographical, ecological, economical and socio-cultural individuality. As a home of nearly nine million people the entire Sundarbans area has emerged as one of the poorest and malnourished region of the South-east Asia. Man-tiger conflict or tiger attacks in riverside settlements around the Sundarbans Reserve Forest in West Bengal, India are a continuous matter of concern. The principal objective of this research is to identify the reasons behind the increasing human-tiger conflict in Indian Sundarbans. Landsat-8 satellite image (path = 138, row = 45, 30 m spatial resolution and eleven spectral bands) has been used to identify the high possible areas of Man-Tiger conflict within the SBR region. The survey involved 100 respondents selected from Gosaba, Kultali, Basanti and Mathurapur II CD blocks in which 85 respondents aged 50 and above were actively participated in the perceptional survey process. Result showed that major proportion of the Sundarbans people is traditionally dependent on forest resources for maintenance of their livelihood. Research identified the principal factors which have been responsible for increasing man-tiger conflict in Sundarbans such as degeneration of forests, habitat loss due to flood and sea level rise, encroachment into wildlife territories for economic activities, intrusion into human settlements for scarcity of wild pray in forest. Deulbari, Dongajora, Bhuvaneswari are the areas of human-tiger conflicts due to closeness with nearest buffer forest area. The adjoining rivers of these two villages Melmel and Gomor are highly vulnerable due to its proximity of reserve forest.

An Innovative Approach to Delineate and Differentiate Clear and Turbid Water Ponds in Indian Sundarban Area Using Sentinel-2 MSI Data

Pond water is the main source of irrigation in the Sundarbans area of West Bengal. The serious issues faced in agricultural lands and ponds are due to salinity. As salinity cannot be detected on high scales through satellite images, in this study the remotely sensed turbidity has been compared and studied with laboratory-measured salinity. The high-resolution Sentinel-2 MSI data with optimum bands for water quality detection have been used in this study. The small agricultural ponds in the study area were not detected by the conventionally used water indices, as the ponds were surrounded by homestead vegetation. Hence, a new index called Pond Probability Spectral Index (PPSI) was formulated and used in the decision tree algorithm to delineate all the ponds. Turbidity indices were used over the extracted ponds to classify them into three classes, clear, turbid and highly turbid. From the field accuracy assessment, one of the turbidity indices outperformed in segregating the ponds with an overall accuracy of 83.3%. It was also found that salinity was inversely proportional to turbidity only when the turbidity value was greater than 100 NTU. The total estimated pond area (average of 3 seasons) in the Sundarban region was 471.66 km2.

Role of Sundarbans bagh bidhwa entrepreneurs in tourism

This study sheds light on the role bagh bidhwa (tiger widow) entrepreneurs play in engendering sustainable rural tourism in the Sundarbans area of Bangladesh. According to the data collected in 2017 by author from the Bangladesh Forest Department, an average of twenty individuals are killed by tigers every year. Drawing upon research on empowerment and entrepreneurial marketing, we discuss how, despite the stigma of widowhood and their divorced status, the women entrepreneurs' stories shed light on their resilience and business acumen. We contribute to existing studies on gender by both theorising and empirically demonstrating how bagh bidhwa entrepreneurs experience and address their othered status interlinked with and exacerbated by other poverty-related problems in the region.

Emotional Intelligence - Its Effect on the Academic Achievement of the Secondary Students in the Sundarbans Region of West Bengal

The purpose of education of an individual is not limited to just garnering information but to prepare the individual for life. This includes developing ones social and emotional skills, such as emotional intelligence. Our present study is conducted on a sample of 100 students of the secondary level in the Sundarbans area of West Bengal, a delta acclaimed for its rich bio-diversity. Though a multitude of researches are conducted in this area, researches in the sector of education are very scarce. The scores of emotional intelligence in our study are self-rated. The regression analytic tool was used to analyze the data. An average correlation of 0.76 was found between the dependent and the independent variable. This denotes a strong positive correlation between academic achievement and emotional intelligence in the context of secondary level students in the Sundarbans area. We should therefore pay more importance to teach our young children to focus on the emotions on the faces in front of us than staring at the screens in front.

Casualisation of Labour as Coping with Cyclone Aila: Peasants’ Perception in the Sundarbans Area of Bangladesh

This paper investigates the coping processes of Bangladeshi peasants after the disaster of Cyclone Aila in 2009. The focus is on the experience of peasants and how they respond to the losses caused by the cyclone. Using 72 in-depth interviews with peasants, shrimp farmers, local leaders, labour contractors, engineers and NGO staff, and surveys of 850 households, this paper analyses the aftermath of Cyclone Aila in two villages in the Satkhira district located in the Sundarbans delta of Bangladesh. One of the villages, Gorkumarpur, was economically backward and poorer than Mollapara village because of its vulnerable geographical location and damaged embankments. By illustrating resilience as the function of coping with vulnerabilities, this paper finds that the peasants can cope with this natural calamity by taking up a range of casual jobs, such as earthwork and brick kiln, to improve their lives and livelihoods. Such casual employment is essential after the initial relief initiatives ended, which shows the ability of the local peasants to protect their family’s survival and secure livelihoods.

Embankment breaching at Indian Sundarban – an assessment on altered primary sediment index properties and fluvial flow parameters

ABSTRACT Failure of manmade embankments at the islands of Sundarban estuaries, India recur almost annually and results in the submergence of fertile agricultural land and claim human lives. Field studies were carried out to investigate the primary index properties of the embankment soil collected from three locations at the concave bends of embankment in the Sundarbans area. A correlation is drawn between alteration of natural layout of embankment soil and modification of its index properties following the traditional construction of embankment. Close introspection of embankment soil under scanning electron microscope were carried out to understand the spatial variations of the susceptibility of soil grains towards erosion for different layers of the embankment sediments. The flow velocities at permissible closest vicinity to river facing embankment wall were much higher than estimated threshold velocities for the entrainment of soil grains and resulted in the formation of undercuts at the basal part of the embankments that triggered its breaching. Finally, from the analyses of obtained results, some preventive measures are recommended to retard the rate of embankment breaching processes which may be expected to provide more sustainability to the erected embankments and will reduce the chances of frequent disasters at the Indian Sundarbans.

Variation in Population Characteristics and Harvesting Pressure Influencing Recruitment Pattern of an Economically Important Fish, Osteomugil cunnesius of Indian Sundarbans

Population characteristics of Osteomugil cunnesius (Longarm mullet) are significant in Indian Sundarbans as the species has high commercial demand in local market. But research work on population dynamics and stock assessment of this mullet species is very limited. The present work aims to determine some of the key management parameters of growth, mortalities, recruitment pattern and exploitation for Osteomugil cunnesius in Sundarbans, India, a world heritage site. The sampling was performed between 2015 and 2017 from the Sundarbans estuary. The parameters of growth, mortalities, exploitation, recruitment pattern, probability of survival, probability of capture, virtual population analysis were recorded. The population dynamics were analysed by FiSAT II (Version 1.2.2) software. The recruitment patterns occurred more or less continuously with one major pulse between May and July. We observed that natural mortality was higher than fishing mortality in 2015 and 2016, whereas, the fishing mortality was higher than the natural mortality in 2017. The result indicated that the fishing pressure increased gradually, which reflected overexploitation of O. cunnesius in 2017. Fishing pressure was increasing over the available stock in the particular Sundarbans area, necessitating appropriate steps to control the fishing pressure. The overall rising impulse of fishing mortality in respective years would be highly alarming to the fish stocks in near future. The present study may be further explored to establish a better fisheries management.

Challenges of Local Coping Capacities due to Climate Change in the Coastal Regions of Bangladesh

Bangladesh is prone to a multitude of natural hazards and vulnerable to the adverse impacts of future change in climatic conditions. One of the most vulnerable aspects in climate change is the fragile coastal ecosystem in Bangladesh. Here, different ecosystems are highly exposed to cyclone, sea level rise, coastal flooding, flash flood, intense riverine floods, droughts and other climatic extremes. Traditionally, in Bangladesh, climatic variations have provided opportunities (resources) and imposed costs (hazards), depending on how society adapted to the environment. In the drive for modernization, evolving technologies and economic and social structures alter existing systems and make many sectors and groups in the ecosystems (especially Coastal Areas) more vulnerable to significant variations in climate and sea level. In this regard, indigenous knowledge and local coping capacities have become a key to survival of the people of the coastal areas (like Sundarbans Area) of Bangladesh. But in recent years, climate change has had a serious impact on the livelihood enterprises and coping capacities. The present paper has been prepared based on secondary sources to examine the often intriguing coping strategies of the coastal areas due to the adverse impacts of climate change. This paper hopes to contribute to our broader understanding of the challenges of the local coping strategies that communities have developed in their quest to stabilize increasingly fragile livelihood systems.

DISCOVERY OF A POTENTIAL SITE FOR COMMUNITY-BASED SUSTAINABLE ECOTOURISM IN THE SUNDARBANS RESERVE FORESTS, BANGLADESH

Abstract Conservation of biological diversity is a pressing need and protected areas are the cornerstones for conserving remaining flora and fauna. However, forest dependent livelihood in countries like Bangladesh making this task very critical. In the case of the poor and forest-dependent livelihood in the Sundarbans area of Bangladesh, an eco-friendly ecotourism may provide an alternative livelihood, which may reduce the overexploitation from the valuable Sundarbans forest ecosystems. Furthermore, this initiative may also serve to aware people on the value of this unique ecosystems. Therefore, this study discusses the scope, benefits and challenges for developing sustainable ecotourism within the protected area. It focuses on the development of a potential site for sustainable ecotourism inside the Sundarbans Reserve Forest. Developing sustainable tourism spots inside the wildlife hub has a high demand among tourists and it is also necessary for the socio-economic development of the local community, moreover, the approach of community-based ecotourism (CBEM) is a suitable strategy for conservation of protected areas.

Concerning public health situation of under-nutrition in children and anemia in women in Indian Sundarbans delta: a community based cross-sectional investigation

The National Family Health Survey-Round 3 in India during 2005–2006 recorded more children and women as anaemic compared to the prevailing situation eight years ago; more children also had wasting. Analysis of this dataset further linked adversity, rather than intrauterine biological processes, with under-nutrition running across generations. Against this background we conducted the present situation assessment in the Sundarbans area of India. The Sundarbans is world’s largest delta with mangrove forest and prone to natural disasters. The current community based investigation was undertaken in five villages under Patharpratima block of the Sundarbans. Participants were selected randomly from the lists of eligible children (aged ≤5 year) and married women (≤49 year) prepared for each of the villages. Interviewer administered questionnaire, tools for anthropometry and hematologic auto-analyzer were used. Data from 561 children and 1145 married women (of which 55 were pregnant) were analysed. Underweight and stunting were recorded in 40 and 51 % of the children respectively. Of the 561 children, 47 (8 %), had severe acute malnutrition. Weight for height z-score reflecting acute and chronic state of nutritional deprivation revealed that four of the five villages were in critical stage. One fourth of the women had low body-mass-index (BMI). Hygienic practices of women were also poor; 41 % reportedly used water, mud/ash and not soap to wash hands after defecation. Anaemia prevalence in women of all the villages was >40 % underscoring a sever public health situation. Factors independently associated with anaemia in non-pregnant women (698/1090; 64 %) were residential-village, low (<18.5 kg/m2) BMI of women (Adjusted Odds Ratio; AOR = 1.39; 95 % CI of AOR 1.02–1.89), non-adoption of family planning method (AOR 1.86; 95 % CI of AOR 1.36–2.54; p < 0.001) and adopting contraceptive practices other than oral pills (AOR 1.84; 95 % CI of AOR 1.32–2.56; p < 0.001). Sundarbans poses its unique public health challenge due to geographical-vulnerability. Securing nutritional support emerges as an immediate need for the study population residing in this natural-disaster prone area of islands and estuaries. The existing situation of anaemia in women requires innovative intervention development and would require addressing health seeking practices. Behavioural intervention appears to be the key.

Community based ecotourism in income generation: a study on the sundarbans adjacent area of Bangladesh

The rich natural and cultural attractions are valuable ingredients for community based ecotourism development in Bangladesh. Every year, a large number of tourists visit in the Sundarbans, which has a significant contribution in the household income to the people who are mostly involved in this sector. The result of the empirical model of Durbin-Watson test revealed the model significant at 1% and 5% level. The income counted here is considered as dependent variable and the age, education, experience, number of tourist served; poor infrastructure; poor communication and transportation; poor knowledge about CBET; lack of government policy etc. as independent variable, the eco cottage quality, natural beauty and security are the dummy variable. The result shows that, the age, number of tourist served and absence of leadership and entrepreneurship ability are significant at 1% and 5% level; experience and the eco cottage quality also found significant for income. However, community based ecotourism industry in Bangladesh is facing many problems, such as lack of transportation and communication system, poor investment, political unrest situation of the country , lack of government policy, poor marketing policy to attract the tourists, poor knowledge about CBET, lack of well-planned accommodation, food, entertainment and other services to satisfy diverse categories of tourists. The issue of safety and security of the tourists of both domestic and foreign origins is also very important for the development of ecotourism in Sundarbans area. Though a policy has been adopted in the recent time for ensuring sustainable development of this sector, the strategies adopted under the policy are not yet being seriously taken up for implementation. Besides, the country requires a strong physical planning strategy to develop its urban and rural areas, and national transportation and communication system to establish connectivity to the tourism spots. There should be a strong marketing policy, business planning as well for the promotion of tourism in the country.

SHARK FISHERIES EXPLOITATION, TRADE, CONSERVATION AND MANAGEMENTIN THE BAY OF BENGAL OF BANGLADESH REGION

The study was conducted during July, 2003 to June, 2013 about landing volumes of shark fishery (sharks and rays) in artisanal and industrial fishing sector only in group- wise not in species wise. In these periods, in artisanal fisheries gill nets (shark nets), set bag nets, long lines and trammel nets exploiting data were analyzed. But from 2012-13 periods in industrial fisheries harvesting data of sharks and rays by trawl fishing were started to record keeping in group wise. During 2012-13 total sharks and rays landing volume contributes only 0.85% (5017 MT) of total the marine fish production of Bangladesh.8&#x0D; During 2010-11 to 2012-13 no sharks and rays product items had been traded from Bangladesh due to international market ban But from 2003-04 to 2009-10 period sharks and rays product with fish maws export to the Myanmar, India, Singapore, Thailand, Hong Kong, China, USA and other countries. Dried and iced sliced meat of shark and rays, its sun-dried hide, bones, fins, tails, teeth and shark liver oil all are sold for local consumers, but only sets of fins (2 pectoral, 2 pelvic, 1 dorsal, 2 anal and 1 caudal fin) and skins were exporting to the foreign markets, which has been stopped now. In the year 2009-10 total 955 MT of sharks and rays product (with fish maws) were exporting and earning (app.) USD 1.60 million. For the conservation and management of shark fishery need National Plan of Action, which exploiting in the MSY and help to banning of critically endangered sharks and rays species. Appropriate law in the Fish Act (at present Fish Act has no forms of restriction for harvesting sharks, while Forestry Act restricts it in Sundarbans area) for sustainable harvesting and conservation of the elasmobranchs. Such law should include how many boats (motorized- and non-motorized) and industrial trawlers could be allowed to harvest sharks from which area, in which season and the allowable limit of harvests; in every case proper ways of fishing methods should strictly be followed. Coastal areas around Saint Martin’s Island and Sundarbans proposed by the Bay of Bengal should be declared as Marine Protected Area as most sharks use these areas as their nursing grounds.

Dynamic Land Use and Coastline Changes in active Estuarine Regions – A Study of Sundarban Delta

Abstract. Alteration of natural environment in the wake of global warming is one of the most serious issues, which is being discussed across the world. Over the last 100 years, global sea level rose by 1.0–2.5 mm/y. Present estimates of future sea-level rise induced by climate change range from 28 to 98 cm for the year 2100. It has been estimated that a 1-m rise in sea-level could displace nearly 7 million people from their homes in India. The climate change and associated sea level rise is proclaimed to be a serious threat especially to the low lying coastal areas. Thus, study of long term effects on an estuarine region not only gives opportunity for identifying the vulnerable areas but also gives a clue to the periods where the sea level rise was significant and verifies climate change impact on sea level rise. Multi-temporal remote sensing data and GIS tools are often used to study the pattern of erosion/ accretion in an area and to predict the future coast lines. The present study has been carried out in the Indian Sundarbans area. Major land cover/ land use classes has been delineated and change analysis of the land cover/ land use feature was performed using multi-temporal satellite images (Landsat MSS, TM, ETM+) from 1973 to 2010. Multivariate GIS based analysis was carried out to depict vulnerability and its trend, spatially. Digital Shoreline change analysis also was attempted for two islands, namely, Ghoramara and Sagar Islands using the past 40 years of satellite data and validated with 2012 Resourcesat-2 LISS III data.

Understanding carnivore killing behaviour: Exploring the motivations for tiger killing in the Sundarbans, Bangladesh

This paper provides the first in-depth exploration of tiger killing behaviour in communities bordering the Sundarbans mangrove forest, Bangladesh. Our findings demonstrate the complexity of carnivore killing behaviour in situations of human–wildlife conflict. We find that killings are not purely retaliatory in nature (i.e. driven by a desire for retribution following livestock depredation or attacks on humans by tigers), and that previous negative experience of tigers is not the sole determinant of villagers’ acceptance of killing behaviour. Inter-related socio-psychological factors (risk perceptions, beliefs about tigers and the people that kill tigers, general attitude towards tigers), perceived failings on the part of local authorities whom villagers believe should resolve village tiger incidents, perceived personal rewards (financial rewards, enhanced social status, medicinal or protective value of tiger body parts), and contextual factors (the severity and location of tiger incidents) motivate people to kill tigers when they enter villages and foster the widespread acceptance of this behaviour. The complexity of these factors highlights the need for conservation practitioners to explore and understand people’s motivations for killing endangered carnivore species, in order to address better the community-led killing of these animals. For the Sundarbans area, knowledge of these motivational factors can be used to develop conservation actions suitable for developing both communities’ capacity and, crucially, desire to co-exist with tigers and to respond with non-lethal action to village tiger incidents.

Role of Secondary Metabolites and Radical Scavenging Aptitude for Better Adaptability of Mangroves in Varying Salinity of Sundarbans, India

Comparative adaptability in five halophytes (Bruguiera gymnorrhiza, Excoecaria agallocha, Heritiera fomes, Phoenix paludosa and Xylocarpus granatum, of which, H. fomes and X. granatum presently are stressed in Sundarbans area) were evaluated with respect to occurrence of total phenol, flavonoids, and radical scavenging ability following ABTS [2, 2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid)], DPPH (1, 1-diphenyl-2-picrylhydrazyl) assay and Fe2+ chelating ability. Amount of total phenol (TP) and flavonoids (TF) were much higher in all taxa grown in Sundarbans than those of mesophytic one. TP and TF were significantly augmented as the substrate salinity increased in B. gymnorrhiza, E. agallocha and P. paludosa but disordered in H. fomes and X. granatum, where increment occurred only up to a certain salinity level. Percent of free radical scavenging of extractants by DPPH and ABTS radical perceived significant correlation with salinity in former three but differ in H. fomes and X. granatum. Ferrous ion chelating ability also showed the similar trend. Owing to polyphenols occurrence and ROS scavengers, the present work clearly indicates the better adaptability of B. gymnorrhiza, E. agallocha and P. paludosa in elevated substrate salinity than those of the other two. Lower ROS scavenging ability of H. fomes and X. granatum also points to their perilous occurrence in elevated saline zones.

Occurrence of Holocene Mammalian Remains and Mollusc Shells from Indian Sundarbans with Environment of Deposition

Mammalian remains of Bubalus bubalis, Rucervus duvauceli of swampy forest environment and mollusc shells of mangrove and distinct fresh water ecosystem recovered from the C dated Peat, Silty Clay and Alluvial layers exposed at depth from 560 cm up to surface at Kumirmari and Dakshin Harishpur, south-east of Kolkata, West Bengal of Indian Sundarbans area were studied for animal remains assemblage zonations and analysis of palaeoenvironment during Holocene. Two Local animal remains assemblage zones were proposed for each section studied viz. KUI: Kumirmari and DHI: Dakshin Harishpur. Correlation of local zones of C dated sediments has revealed two RAZ: Regional Animal remains Assemblage Zones viz. RAZ-I Bubalus bubalis – Rucervus duvauceli -Telescopium telescopium Meretrix meretrix Bankia sp. Assemblage Zone and RAZ-II Tarebia lineata Lymnaea (Pseudosuccinea) acuminata f. Patula Indoplanorbis exustus Gyraulus convexiusculus Parreysia sp. Bellamya bengalensis Pila globosa Gabbia orcula Brotia costula Melanoides tuberculata Corbicula striatella Tarebia granifera Assemblage Zone. The environmental phases of deposition of Holocene sediments of Sundarbans, India as revealed from the Regional assemblage zones indicate Swampy mangrove condition during c. 5000–2000 years BP followed by Supra-tidal fresh water condition since c. 2000 years BP.