Aquatic Sciences Overview Article Biodiversity and its conservation in the Sundarban Mangrove Ecosystem (original) (raw)
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Biodiversity and its conservation in the Sundarban Mangrove Ecosystem
Aquatic Sciences-Research Across Boundaries, 2006
The Sundarban, covering about one million ha in the delta of the rivers Ganga, Brahmaputra and Meghna is shared between Bangladesh (~60 %) and India (~40 %), and is the world's largest coastal wetland. The area experiences a subtropical monsoonal climate with an annual rainfall of 1,600-1,800 mm and severe cyclonic storms. Enormous amounts of sediments carried by the rivers contribute to its expansion and dynamics. Salinity gradients change over a wide range of spatial and temporal scales. The biodiversity includes about 350 species of vascular plants, 250 fi shes and 300 birds, besides numerous species of phytoplankton, fungi, bacteria, zooplankton, benthic invertebrates, molluscs, reptiles, amphibians and mammals. Species composition and community structure vary east to west, and along the hydrological and salinity gradients. Sundarban is the habitat of many rare and endangered animals (Batagur baska, Pelochelys bibroni, Chelonia mydas), especially the Royal Bengal tiger (Panthera tigris). Javan rhino, wild buffalo, hog deer, and barking deer are now extinct from the area. Large areas of the Sundarban mangroves have been converted into paddy fi elds over the past two centuries, and more recently into shrimp farms. The Sun-
Mangrove biodiversity in the Bangladesh Sundarbans
2018
The dataset contains biodiversity and environmental data collected from the Sundarbans mangrove forest in Bangladesh. The rows in the first column contains the plot (permanent sample plot, PSP) numbers. The remaining columns represent the: > estimated values of the alpha, beta and gamma diversity measures (for q =1,2,& 3) > environmental and biotic variables & > latitude & longitude of the plots Plot level raw species data can be collected upon request from the Bangladesh Forest Department.
Mangrove wetland ecosystems in Ganges-Brahmaputra delta in Bangladesh
Frontiers of Earth Science in China, 2008
The Sundarbans is one of the productive mangrove wetland ecosystems in the Ganges-Brahmaputra delta in Bangladesh. The delta is undergoing rapid ecological changes due to human activity. In the present study, surface water salinity data from 13 rivers of the Sundarbans were collected in order to investigate the saline water intrusion in the mangrove wetlands. Results demonstrate that saline water has penetrated the upstream area as river water salinity has increased significantly in 1976 compared to the year 1968. The soil and river water salinity data also shows that it has crossed the water salinity threshold line in most parts of the Sundarbans wetlands. These observations are due to the construction of Farakka Barrage in 1975, which reduced the water discharge of the Ganges River from 3700 m 3 /s in 1962 to 364 m 3 /s in 2006. The shortage of freshwater discharge to the deltaic area is trailing active ecosystems function, especially in the dry season in the south western region in Bangladesh. The objective of this study is to understand and analyze the present degraded mangrove wetland ecosystems and their negative impacts. The findings of this study would contribute to the formulation of the mangrove wetland ecosystems management plan in the Ganges delta of Bangladesh.
Mangrove species distribution and water salinity: an indicator species approach to Sundarban
Journal of Coastal Conservation, 2017
The present study attempts to reveal the impact of salinity on mangrove species in terms of species distribution, and their trend of adapting to salinity changes. The study considers the mangrove species of entire Sundarban encompassing India and Bangladesh. The mangrove species distribution depends on a great deal on the salinity regime. Each mangrove species has optimal salinity range for its preferred habitat. This preference, as well as its tolerance level, may alter with the changing environmental regime. Based on this hypothesis, a few indicator species have been identified according to the preferred salinity. Ceriops and Avicennia have been identified as high salinity indicator species which are found in high frequency in the polyhaline zones, whereas Nypa and Heritiera are recognized as low salinity indicator species which show high abundance in oligohaline to mesohaline zones. Exoecaria and Bruguiera, the medium salinity indicator species, are found almost everywhere but are most abundant in the mesohaline zones. This study will help in evaluating the adaptive capacity of mangroves and also could build a functional relationship between their occurrences as indicator species with respect to the salinity.
Threats to the Sundarbans Mangrove Wetland Ecosystems
2009
Through their complex network of river channels, the Ganges, Brahmaputra and Meghna Rivers cover an area of about 1.76 million km 2 , their boundaries extend across different countries such as Bangladesh, Bhutan, China, India, and Nepal. The Sundarbans are found at the coast of the Ganges River and are known as the world's single largest mangrove forest with 3.5 percent of the world's mangroves covering an area of 6017 km 2. The Sundarbans wetlands act as a natural shield that protects the coastal area from storm surges and cyclones in pre and post monsoon periods. However, due to increased in irrigation of agriculture, industrial activity and the diversion of Ganges water at Farakka Barrage (India) in early 1975, both siltation and salinity have increased in the Sundarbans which is threatening the Sundarbans ecosystems. Consequently the dominant Sundari (Heritiera fomes) and Goran (Ceriops decendra) are affected by top-dying disease which is recognized as a key management concern. The Ganges water sharing is not just a geo-technopolitical problem; it is also a humanitarian problem. So, interaction and educational awareness between concerned states are of great significant. The objective of this paper is to make a contribution towards the development and implementation of management plan for mangrove wetlands resources and to ensure that fresh water is supplied to the Sundarbans by the Ganges. Water salinity simulation and modeling would be a proper tool for decision making and allow planners to protect the Sundarbans ecosystems in future.
Aquatic picture of Indian Sundarban Mangroves
We present evidence that the Indian Sundarbans is experiencing the effects of climate change over the last three decades. Observations of selected variables, such as the surface water temperature, salinity, pH, dissolved oxygen, and transparency show significant long-term variation over a period of 27 years (1980-2007). Specifically, the temperature in these waters has risen at the rate of 0.5°C per decade, much higher than that observed globally or for the Indian Ocean. Increasing melting of Himalayan ice might have decreased the salinity at the mouth of the Ganges River, at the western end of this deltaic complex. At the same time, salinity has increased on the eastern sector, where the connections to the meltwater sources have become extinct due to heavy siltation of the Bidyad-hari Channel. The long-term changes in dissolved oxygen, pH level, transparency and water quality are also examined. The ecological impact of such changes warrants future study.
IASIR Publishers, 2014
Sundarban mangrove ecosystem is the world largest contiguous mangrove forest and is the cradle for both aquatic and terrestrial biota. The mangrove biodiversity of the Central and Eastern parts of Indian Sundarbans shows a difference in species abundance and can also be identified from remote sensing images. There is an exclusion of few fresh water loving true mangrove members and other endangered associates namely Rhizophora sp, Kandelia candel, and Heritiera fomes from the central parts with relatively high abundance of edaphic sub-climax Phoenix paludosa and salt loving Avicennia sp, than in the Eastern parts. The analysis of remote sensing satellite image along with in-field biodiversity assessments have portrayed a variation in mangrove diversity between these two parts of Indian Sundarbans which is discussed in this paper.
Hydrologic monitoring and analysis in the Sundarbans mangrove ecosystem, Bangladesh
Journal of Hydrology, 2007
The unique habitat of the Sundarbans mangrove ecosystem is dependent upon the hydrological regime. Therefore, a comprehensive study to understand the hydrologic behaviour and the changes that have taken place due to anthropogenic activities in and around the area is fundamental to the management of natural resources and environment. In the past, ad hoc and uncoordinated efforts were made due to the inherent inaccessibility and high cost of data collection. The present article documents the results of the hydrologic monitoring, modelling and analysis in the Sundarbans. The study results show that the annual maximum tidal range has increased by about 0.75 m in the eastern and central parts during the last two decades. About 60% area remains in higher salinity condition (>20 ppt) for at least 1.5 months in a year. Organic pollution in the waterways is within the Environmental Quality Standard (EQS) of Bangladesh with the average Dissolved Oxygen (DO) of 5.99 mg/L. Total Ammonia, Nitrate (NO 3-N) and Phosphate (PO 4-P) level are present in sufficient quantity for the aquatic life to survive and are within EQS limit. Lead and Chromium occasionally exceed EQS limit especially along the large barge routes in the western part. The data and information presented in the paper will serve as a baseline for future hydrological and environmental studies.
Bangladesh Sundarbans: Present Status of the Environment and Biota
Diversity, 2015
The Sundarbans is a deltaic mangrove forest, formed about 7000 years ago by the deposition of sediments from the foothills of the Himalayas through the Ganges river system, and is situated southwest of Bangladesh and south of West Bengal, India. However, for the last 40 years, the discharge of sediment-laden freshwater into the Bay of Bengal through the Bangladesh part of the Sundarbans Mangrove Forests (BSMF) has been reduced due to a withdrawal of water during the dry period from the Farakka Barrage in India. The result is two extremes of freshwater discharge at Gorai, the feeding River of the BSMF: a mean minimum monthly discharge varies from 0.00 to 170 m 3 •s −1 during the dry period with a mean maximum of about 4000 to 8880 m 3 •s −1 during the wet period. In the BSMF, about 180 km downstream, an additional low discharge results in the creation of a polyhaline environment (a minimum of 194.4 m 3 •s −1 freshwater discharge is needed to maintain an oligohaline condition) during the dry period. The Ganges water carries 262 million ton sediments/year and only 7% is diverted in to southern distributaries. The low discharge retards sediment deposition in the forestlands' base as well as the formation of forestlands. The increase in water flow during monsoon on some occasions results in erosion of the fragile forestlands. Landsat Satellite data from the 1970s to 2000s revealed a non-significant decrease in the forestlands of total Sundarbans by 1.1% which for the 6017 km 2 BSMF is equivalent to 66 km 2. In another report from around the same time, the estimated total forestland loss was approximately 127 km 2. The Sundarbans has had great influence on local freshwater environments, facilitating profuse growth of Heritiera fomes (sundri), the tallest (at over