Vertical occurrence of soil urease activity along with ammonia content from three distinct regions viz. Deep forest region (No tidal action and wave attack occurs as it is furthest from river shore and it contains maximum content of organic carbon and minimum soil salinity and silicate concentration. In this zone plenty of pneumatophores, below ground root and dense vegetation are found), Rooted region (It is situated in between Deep forest region and Un-rooted region. This region contains only pneumatophores but it is devoid of long roots and vegetations. It faces wave attack and tidal action less than that of Un-rooted region) and Un-rooted region (It is closest to river shore and faces maximum wave attack and tidal action; it contains minimum organic carbon but maximum soil salinity and silicate concentration. This zone is totally devoid of any roots, pneumatophores and vegetations) of Sundarban mangrove forest ecosystem, India revealed an interesting explanation. Soil urease activity showed a decreasing pattern with increase in depth from the deep forest region of the Sundarban forest ecosystem. Soil urease activity was found to be more sensitive to soil temperature and pH rather than soil salinity. This ensured that soil urease along with the microbes present in the Sundarban forest ecosystem are more tolerant to fluctuation in salinity than that of temperature. Soil ammonia concentration was found to be directly governed by the soil urease activity [The regression equation is Ammonia in soil = −1.64 + 0.0402 Urease Activity (R-Sq = 62.9%, P < 0.001, n = 41)].
The dynamics of methane (CH4) flux in relation to populations of methanogenic and methanotrophic bacteria was studied under the different biophysical conditions of the Indian Sundarban mangrove ecosystem. Soil depth profile analysis (up to 60 cm) in the lower littoral zone (LLZ) revealed that a methanogenic population of 6.45 ± 0.19 × 104 cells/g dry weight (dry wt) of soil accounted for a CH4 production rate of 6.23 ± 3.53 × 103 µmol m−2 day−1, whereas in the surface soil, a methanogenic population of 3.34 ± 0.37 × 104 cells/g dry wt of soil accounted for a CH4 production rate of 31.6 ± 0.57 µmol m−2 day−1. The CH4 oxidation rate at 60 cm depth in the LLZ was 24.42 ± 1.28 µmol m−2 day−1, with an average methanotrophic population of 1.33 ± 0.43 × 104 cells/g dry wt of soil, whereas in the surface soil, the oxidation rate and average population were 3.38 ± 1.43 × 103 µmol m−2 day−1 and 12.80 ± 2.54 × 104 cells/g dry wt of soil, respectively. A similar soil profile in terms of CH4 dynamics and the populations of methanogenic and methanotrophic bacteria was found in the mid‐littoral and upper littoral zones of the studied area. The results demonstrate that most of the produced CH4 (approximately 60%) was oxidized by methanotrophic bacteria present in the soil, thus revealing their principal role in regulating the CH4 flux from this unique ecosystem.
Abstract. The study was governed by the objective of investigating the antimicrobial effects of mangrove leaf extracts. The fresh and dried leaf extracts from Avicennia marina (Forssk.) Vierh., Avicennia officinalis L., Aegiceras corniculatum (L.) Blanco, Aegialitis rotundifolia Roxb., Acanthus ilicifolius L, Lumnitzera racemosa Willd., Excoecaria agallocha L. and Sonneratia apetala Buch-Ham. were found to have inhibitory effects on the milk spoilage microflora obtained from curd sample. Methanol and Acetone were used as extraction solvents and in comparison, extracts by acetone were observed to suppress the microbial growth to lesser extents. Leaf extracts of A. marina, A. officinalis L. racemosa and A. rotundifolia were able to exert relatively greater inhibitory effect on the milk spoilage microbial broth than others, although all the species expressed some degree of suppression. Interestingly A. rotundifolia, S. apetala, L. racemosa and E. agallocha demonstrated greater efficiency in formation of larger growth inhibition zones on the petri plates. The extracts obtained from dry leaves produced greater adverse effects of the microbes than the raw leaf extracts. The data generated were analyzed with the help of 'ANOVA: Single factor' and 'F-test: Two sample for variance' and data sets were of statistical significance at 0.05 level of significance as null hypothesis was rejected.
Abstract. An experiment was performed on selected pennate diatom species collected from the well mixed waters of the Hooghly Estuary with the aim of distinguishing the ones with qualities to be employed as monitors of their ecosystem. The Hooghly Estuary is enriched with domestic, sewage and agricultural effluents and coastal upwelling along with tide-mediated advective circulation from the mangrove forests ensure concomitant nutrient pool replenishment in this ecoregion. There have been several attempts to establish certain centric diatom species as bioindicators in various parts of the world owing to their better responsiveness to sudden shifts in stoichiometry but hardly any with pennate diatoms. Pennate diatoms are typical benthic mat formers in the intertidal regions, on submerged surfaces and thus bear greater feasibility to be employed as accurate pointers to long term deviations in their respective ecosystems, in spite of the greater sensitivity of the centric diatoms. The study was carried out in laboratory controlled environment to minimize the interference from other extrinsic factors compromising the outcome and also due to the fact that such studies to be performed in natural conditions require a decent financial support and time to conclusively arrive upon the objectives. From the present endeavour it was inferred that Nitzschia sigmoidea, Pleurosigma angulatum and Ulnaria oxyrhyncus (formerly Synedra ulna var. oxyrhyncus) stood a good chance of being recruited as bioindicators to eutrophic well mixed estuaries, similar to the one they had been sampled from.
A case study was undertaken to observe the variations in the concentrations of the dissolved inorganic nitrogen species in the surface sediments of the littoral compartments at Bakkhali and Frasergunj situated within the single coastal stretch at the southernmost tip of West Bengal, India. Effects, if any, of the presence or absence of bioturbations on the variability of the dissolved nitrate-nitrogen, nitrite-nitrogen, ammonia-nitrogen, total dissolved nitrogen and the cumulative concentration of former three variables in the beach surface sediments were also noted. On site nitrite-nitrogen was found in alternate fluctuating patterns throughout the beach zonations with gradual lowering and peaking within each zone. An evidently prominent fact was the independence of dissolved inorganic nitrogen species from bioturbatory influences in the surface sediments of wave exposed littoral environments at the study sites. That effect might become significant in a vertical profile but from the data procured it can be stated that inorganic nitrogen species concentrations in surface beach sediments are not entirely perturbed by bioturbations and are governed by many other environmental parameters. A Pearson correlation performed on the normalized data sets revealed that there existed a fairly significant correlation in between the both the beach sediments with r-values ranging from -0.97 to +0.99 among the five variables considered at 95% confidence level. ANOVA Single factor yielded values in support of the rejection of the null hypothesis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.