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Abstract:The Sundarbans mangrove forest is an important resource for the people of the Ganges Delta. It plays an important role in the local as well as global ecosystem by absorbing carbon dioxide and other pollutants from air and water, offering protection to millions of people in the Ganges Delta against cyclone and water surges, stabilizing the shore line, trapping sediment and nutrients, purifying water, and providing services for human beings, such as fuel wood, medicine, food, and construction materials. However, this mangrove ecosystem is under threat, mainly due to climate change and anthropogenic factors. Anthropogenic and climate change-induced degradation, such as over-exploitation of timber and pollution, sea level rise, coastal erosion, increasing salinity, effects of increasing number of cyclones and higher levels of storm surges function as recurrent threats to mangroves in the Sundarbans. In this situation, regular and detailed information on mangrove species composition, their spatial distribution and the changes taking place over time is very important for a thorough understanding of mangrove biodiversity, and this information can also lead to the adoption of management practices designed for the maximum sustainable yield of the Sundarbans forest resources. We employed a maximum likelihood classifier technique to classify images recorded by the Landsat satellite series and used post classification comparison techniques to detect changes at the species level. The image classification resulted in overall accuracies of 72%, 83%, 79% and 89% for the images of 1977, 1989, 2000 and 2015, respectively. We identified five major mangrove species and detected changes over the 38-year (1977-2015) study period. During this period, both Heritiera fomes and Excoecaria agallocha decreased by 9.9%, while Ceriops decandra, Sonneratia apelatala, and Xylocarpus mekongensis increased by 12.9%, 380.4% and 57.3%, respectively.

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This experiment was conducted with the aim to study the effect of replacing egg yolk with soybean lecithin (SL) for cryopreservation of Black Bengal buck semen. Sexually matured Black Bengal buck (n = 5) were used and the ejaculates were obtained using an artificial vagina method. The semen samples were pooled and diluted in Tris extender with 5% Glycerol containing either 15% egg yolk (control group) or SL at different concentrations (1% SL, 1.5% SL and 2% SL). The semen samples were filled in straws and cooled gradually to 5 °C. Semen straws were equilibrated for 3 hours at 5°C and were frozen in static liquid nitrogen vapor and stored in liquid nitrogen. Semen samples were evaluated after initial dilution, after completion of equilibration and after freeze thawing for in vitro sperm characters such as sperm motility, functional membrane integrity and malondioldehyde (MDA) concentration. Semen samples preserved in extender containing 1% SL was able to maintain in vitro sperm characters similar to the extender containing egg yolk. However, significant (P<0.05) reduction in all semen parameters was observed as the concentration of soybean lecithin increased above 1% level. It is concluded that an extender containing soybean lecithin @ 1% with 5% Glycerol can be used for replacing egg yolk for cryopreservation of Black Bengal buck semen.

Aim: This study aimed to study the electrophoretic properties of seminal plasma and sperm proteins of Black Bengal buck semen and their correlation with in vitro sperm characters and freezability. Materials and Methods: Semen ejaculates from nine Black Bengal bucks were collected by artificial vagina (n=20/buck). Ejaculates were evaluated for in vitro sperm characters and electrophoretic profile of seminal protein. In vitro sperm characters were evaluated immediately after collection, after completion of equilibration period, and after freeze-thawing. For seminal protein studies, seminal plasma proteins were precipitated by ice-cold ethanol method, and sperm proteins were extracted by Triton X detergent extraction method. Discontinuous sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed to assess the molecular weight of seminal proteins. Correlation between in vitro sperm characters and protein bands was determined by Pearson's correlation coefficient, and two-way ANOVA was applied to find the individual buck differences. Results: Significant difference (p<0.01) among the bucks was noticed in the in vitro sperm characters evaluated at all the three stages of semen evaluation such as immediately after collection, after completion of equilibration period, and post-freeze thawing. Progressive loss of sperm motility, membrane integrity, and other in vitro sperm characters were noticed during cryopreservation. A total of ten protein bands in the molecular weight ranging from 17 to 180 kDa were found in the SDS-PAGE of seminal plasma proteins, while nine bands of 17-134 kDa were observed in sperm proteins. Seminal plasma proteins of molecular weight 75, 62-49, 20, and 17 kDa and sperm proteins of 75, 20, and 17 kDa were present in all the nine bucks (100%) screened, and variation among the bucks was noticed for the presence of other proteins. Seminal plasma protein of 180-134 kDa showed a negative correlation with individual motility (−0.716) and functional membrane integrity of sperm cells (−0.724) in post-freeze-thaw analysis and 48 kDa protein had a positive correlation with individual motility (0.649) and functional membrane integrity of sperm cells (0.664) in post-thaw analysis. Sperm proteins of 63 kDa had a negative correlation (−0.616) with sperm concentration in neat semen. Conclusion: Variation among the bucks was noticed in the in vitro sperm characters and semen freezability. Correlation between seminal proteins and in vitro sperm characters and semen freezability had been found which might be useful as a tool to select breeding bucks.

Ecohydrological changes in large rivers of the world result from a long history of humandimensions and climate. The increasing human population, intensified land use, and climate change haveled to a decline in the most critical aspect of achieving sustainable development, namely, that of waterresources. This study assessed recent hydromorphological characteristics of the tropical Tana River inKenya using flow duration curve, and geospatial techniques to gain a better understanding of humanimpacts over the last two decades and their consequences for new development projects. The results showthat all extremal peak, low, and mean discharges exhibited significant increasing trends over a period of17 years. Dam construction represents a 13% reduction of the maximum discharge and a 30% decrease inlow flows, while post-regulation hydrological changes indicated an increase of 56 and 40% of high flowsand low flows respectively. Dominant flow was observed to be higher for the current decade than theprevious decade, representing a rise of the dominant streamflow by 33%. The assessment of fourmorphologically active sites at the downstream reach showed channel adjustments which support thechanges in the flow regimes observed. The channel width increased by 8.7 and 1.9% at two sites butdecreased by 31.5 and 16.2% for the other two sites under study during the time period. The resultsunderscore the contribution of other main human modifications, apart from regulation, such as increasedwater abstraction and inter basin transfer, up-stream land use and anthropogenic climate change to assessthe ecohydrological status in this river basin. Such streamflow regime dynamics may have implicationson water resource management, riverine environments, and development of new water projects.

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This research reveals the magnitude of mangrove area loss and future impacts on mangrove species composition and distribution due to rise in Mean Sea Level (MSL). In this study, a geospatial model of potentially inundated areas was developed using Digital Elevation Model (DEM) data to assess the potential impacts of sea level rise (SLR) on the spatial distribution of mangrove species and estimate the potential inundation and subsequent mangrove area loss. The mangrove areas of 2646 ha, 9599 ha and 74,720 ha are projected to be inundated and subsequently lost by the end of the twenty first century for the low, medium and high SLR scenarios respectively under the net subsidence rate À2.4 mm/ year relative to the baseline year 2000. All the major five mangrove species of the Bangladesh Sundarbans will be affected and this can potentially contribute to a change in the present species composition and biodiversity of the forest. Results suggest that, under the extreme scenario, inundation and subsequent loss of different mangrove species will be substantial and this can bring a massive change in the species composition and their spatial distribution in the Bangladesh Sundarbans.