Cell Size versus Taxonomic Composition as Determinants of As (III &V) Sensitivity in the Estuarine Diatom Communities

Despite scarce studies have analyzed the relative growth inhibition of As (III) and As (V) to diatom, clear pattern of interspecies difference have been shown, identifying cell size as a key property determining the sensitivity of diatom to As. Evidence from cultures suggests that cell size is a key factor in determining the extent of arsenic (III) & (V) stress of diatom, with relatively lesser effects of As (V) than As (III) on small cells. Cent percent growth inhibition was observed for large size group (Coscinodiscus radiatus, Surirella, Amphipleura, Thalassiothrix, Cyclotella and Thalassiosira decipiens) relative to smaller size group (Skeletonema cf. costatum, Navicula rhombica, Amphora hyaline, Nitzschia longissima except Thalassisira. Interspecies differences in As tolerance by diatom in the mangrove ecosystem indicates cell size could be only one factor contributing to these differences. The results show that 81.7% of total arsenic was uptaken from culture media originally amended with arsenic. Looking to the extreme tolerance and arsenic removal efficiency, application of the species with smaller cell size relative to the other tested diatom for bioremediation purpose can be envisaged.

Salt tolerant culturable microbes accessible in the soil of the Sundarban Mangrove forest, India

Sundarban Mangrove forest is highly productive marine ecosystem where halophilic microbes actively participate in bio-mineralization and biotransformation of minerals. The population of aerobic halophilic microbes was studied to determine their distribution with the availability of different physicochemical parameters with increasing depth of this forest sediment. The present study revealed that microbes present in the top soil region were less tolerant to fluctuation in salinity than the middle and bottom segment. Microbes isolated from bottom segment showed higher growth rate in anaerobic condition. A decreasing trend of total microbial population and organic carbon content of soil were found with increase in depth. In contrary a reverse profile was found for salinity. A significant stratification was found to exist among microbial population and the salty nature of the soil of Sundarban Mangrove forest.

Distribution of Antimony in a Tropical Estuary Dominated by Mangroves

Seasonal variation of antimony was studied in order to characterize its distribution in estuarine water, pore water, sediment, and digenetic behavior in the Sundarbans mangrove ecosystem. The mean concentration of dissolved inorganic Sb ranged between 230.8 and 303.1 ng L–1 over the period of study with a minimum during the post-monsoon closely associated with spring diatom bloom. Molecular diffusion flux of Sb was found greater than its value advected and deposited on sediment-water interface and there was significant remobilization of Sb in the Sundarbans mangrove ecosystem.

Monsoonal Influence on Evapotranspiration of the Tropical Mangrove Forest in Northeast India

Evapotranspiration (ET) is an important part of the water cycle. This study reports on the monsoonal influence on the temporal variation in evapotranspiration of an extremely water conservative and salinity stressed tropical mangrove forest at the land-ocean boundary of northeast coast of India. The magnitude and dynamics of evapotranspiration (ET) exhibited seasonality dominated by monsoon and evaporation rate was greater (0.055 ± 0.015 g·m-2·s-1) during the monsoon than in pre-monsoon (0.049 ± 0.018 g·m-2·s-1) and post-monsoon (0.044 ± 0.012 g·m-2·s-1). Seasonal difference in evapotranpiration was mostly due to fluctuation of canopy resistance, which was the minimum during monsoon when relative humidity was greater than in the dry season (pre- and post-monsoon) and deficiency of water supply (ET ≈ ETeq) was minimum. Evapotranspiration in the Sundarban mangrove ecosystem is the predominant biophysical processes that recycles 67.7% of total precipitation annually to the atmosphere, and has significant monsoonal influence.