Abhijit Mitra

Abstract: Climate change is being experienced intensely in the mangrove dominated deltaic complex of Indian Sundarbans. Deglaciation of Gangotri glacier in the Himalayan range and several anthropogenic influences has accelerated the phenomenon since last two decades. Four indicators (surface water temperature, salinity, dissolved oxygen, and transparency) considered in the present study exhibited significant correlations with global warming and caused considerable alteration of hydrological parameters over a period of 27 years. Owing to varied geographical features in the western and eastern sectors of the deltaic complex, the foot prints of climate change were perceived in different pattern and scale. The surface water temperature showed increasing trend in both sectors (6.14% and 6.12% rise in western and eastern sectors respectively). The transparency reduced by 25% in both western and eastern sectors. This may be the effect of increased erosion, anthropogenic activities and silt contribution by the River Ganges. The salinity and dissolved oxygen exhibited contradictory trends in the western and eastern sectors, which may be attributed to deglaciation process in the Himalayan range. The blockage of the major rivers in the eastern Indian Sundarbans by heavy silt and solid wastes from the adjacent city of Kolkata posed serious problems to the island dwellers by way of increasing salinity and decreased dissolved oxygen. Documentation of stenohaline phytoplankton species in upstream regions of eastern Indian Sundarbans (secondary source) confirmed the intrusion of sea water from Bay of Bengal. Such intrusion has serious adverse effect on the livelihood of the local people.

Abstract: The biochemical composition of red seaweeds, Catenella repens was investigated in this present study along with subsequent analysis of relevant physico-chemical variables. In this study, the relationship between the nutritive components of this species and the ambient environmental parameters was established. Protein content varied from 2.78 ± 0.30% of dry weight (stn.3) to 16.03 ± 0.96% of dry weight (stn.1) with highest values during monsoon. The protein levels were positively correlated with dissolved nitrate content and negatively correlated with water temperature (except stn.3) and salinity. Carbohydrate content of this species varied significantly ( p< 0.05) during pre-monsoon between stations and the values showed positive relationship with salinity and surface water temperature. In contrast to carbohydrate, lipid concentration was lowest in values and varied very slightly between seasons and stations. Astaxanthin content of the seaweed species was greater in pre-monsoon than monsoon and post-monsoon in all the selected stations. Compared with the three seasons, samples of red seaweed collected in pre-monsoon has high carbohydrate–astaxanthin in contrast to protein–lipid which showed high values during monsoon. Statistical analysis computed among the environmental and biochemical parameters suggests the potential role played by the abiotic parameters on biosynthetic pathways of seaweed. This paper also highlights the influence of the nutritional quality of water that can be used for mass cultivation of Catenella repens.

Abstract: The impact of global warming, through the predicted sea level rise, on Sundarbans estuary, in the Bay of Bengal is an inevitable phenomenon. While the mitigation measures have to be primarily at the global level as well as at local level, the adaptation strategy will also involve participation of global and local communities. This study has clearly shown that the people living around the mangrove forests have to be provided with a sustainable alternate livelihood to cope with the increasing salinity in the region. As regards the destructive livelihood activities practiced by the villagers of Sundarbans, generating employment through other livelihood options and training in skill development have to be resorted to. However, all these socio-economic activities need huge amount of fund support at the beginning. Since Sundarbans mangrove, if properly conserved, can store billions of tonnes of carbon thus mitigating the effect of global warming, the people of the region also need to be duly compensated under REDD+ projects. The study has shown the prospect of conservation of Sundarbans mangrove flora and fauna through active participation of local people. The global community cannot avoid their commitment for conserving one of the largest sink for atmospheric carbon.

Abstract: The aim of this study is to determine the heavy metals (Zn, Cu, Pb and Cd) in edible finfish species (Polynemus paradiseus, Tenualosa ilisha, Liza parsia, Liza tade and Stolephorus commersonii) and compare the level of heavy metals determined in the Gangetic delta region earlier. Finfish species were sampled from 4 different stations. Levels of four selected heavy metals were determined in the muscle of edible finfish species in the Gangetic delta region using a Perkin-Elmer Sciex ELAN 5000 ICP mass spectrometer and expressed as mg kg-1 dry weight. To determine whether heavy metal concentrations varied significantly between sites and species, analysis of variance (ANOVA) was performed. In addition to, heavy metal concentrations were compared with WHO and FAO’s permited levels. In finfish species the concentrations of Zn, Cu, Pb and Cd ranged from 12.00±0.66 – 119.66 ±1.53, 10.89±0.19– 73.22±0.83, 2.33±0.09–17.88±0.52 and BDL–3.12±0.10 respectively. For Zn and Cu, accumulated metal concentrations in Stn. 4 were significantly higher than accumulated metal concentration in Stn 1 and Stn 2. For Pb, significantly stational difference between stations was not found. Between all studies fish species, lowest metal acculation values was found for S. commersonii (p<0.05). The selected heavy metals in finfish muscle (except Zn in Liza parsia in station 1) were also within the permissible limits for human consumption as indicated by the Food and Agricultural Organization.

Abstract: There has been significant recent interest in the commercial utilisation of algae based on their valuable chemical constituents many of which exhibit multiple bioactivities with applications in the food, cosmetic, agri- and horticultural sectors and in human health. Compounds of particular commercial interest include pigments, lipids and fatty acids, proteins, polysaccharides and phenolics which all display considerable diversity between and within taxa. The chemical composition of natural algal populations is further influenced by spatial and temporal changes in environmental parameters including light, temperature, nutrients and salinity, as well as biotic interactions. As reported bioactivities are closely linked to specific compounds it is important to understand, and be able to quantify, existing chemical diversity and variability. This review outlines the taxonomic, ecological and chemical diversity between, and within, different algal groups and the implications for commercial utilisation of algae from natural populations. The biochemical diversity and complexity of commercially important types of compounds and their environmental and developmental control are addressed. Such knowledge is likely to help achieve higher and more consistent levels of bioactivity in natural samples and may allow selective harvesting according to algal species and local environmental conditions for different groups of compounds.

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Abstract: With parks and protected areas insufficient to sustain global biodiversity, the role of private land in biodiversity conservation is becoming increasingly significant. This paper reviews global voluntary and involuntary strategies for private land conservation. Involuntary strategies can achieve effective conservation outcomes, but often lack social acceptability. In contrast, voluntary strategies enjoy greater social acceptance but may not achieve sufficient uptake to have meaningful conservation objectives. Based on the review, we propose a classification system for private land conservation as a complement to the International Union for Conservation of Nature's (IUCN's) classification of global protected areas. The classification system provides a framework for identifying and describing conservation strategies on private land on the dimension of tenure and security. It also identifies opportunities and vulnerabilities in achieving conservation on private land while emphasising the need for systematic ...

Abstract: Covering approximately 10,000 km2 the Sundarbans in the Northern Bay of Bengal is the largest contiguous mangrove forest on earth. Mangroves forests are highly productive and diverse ecosystems, providing a wide range of direct ecosystem services for resident populations. In addition, mangroves function as a buffer against frequently occurring cyclones; helping to protect local settlements including the two most populous cities of the world, Kolkata and Dhaka, against their worst effects. While large tracts of the Indian Sundarbans were cleared, drained and reclaimed for cultivation during the British colonial era, the remaining parts have been under various protection regimes since the 1970s, primarily to protect the remaining population of Bengal tigers (Panthera tigris ssp. tigris). In view of the importance of such forests, now severely threatened worldwide, we trace the areal change that the Indian Sundarbans have undergone over the last two-and-a-half centuries. We apply a multi-temporal and multi-scale approach based on historical maps and remote sensing data to detect changes in mangrove cover. While the mangroves’ areal extent has not changed much in the recent past, forest health and structure have. These changes result from direct human interference, upstream development, extreme weather events and the slow onset of climate change effects. Moreover, we consider the role of different management strategies affecting mangrove conservation and their intersection with local livelihoods.

Abstract: 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 Bidyadhari 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.