Rhizosphere microbiome metagenomics of gray mangroves (Avicennia marina) in the Red Sea

AbstractMangroves are unique, and endangered, coastal ecosystems that play a vital role in the tropical and subtropical environments. A comprehensive description of the microbial communities in these ecosystems is currently lacking, and additional studies are required to have a complete understanding of the functioning and resilience of mangroves worldwide.In this work, we carried out a metagenomic study by comparing the microbial community of mangrove sediment with the rhizosphere microbiome of Avicennia marina, in northern Red Sea mangroves, along the coast of Saudi Arabia. Our results revealed that rhizosphere samples presented similar profiles at the taxonomic and functional levels and differentiated from the microbiome of bulk soil controls. Overall, samples showed predominance by Proteobacteria, Bacteroidetes and Firmicutes, with high abundance of sulfate reducers and methanogens, although specific groups were selectively enriched in the rhizosphere. Functional analysis showed significant enrichment in ‘metabolism of aromatic compounds’, ‘mobile genetic elements’, ‘potassium metabolism’ and ‘pathways that utilize osmolytes’ in the rhizosphere microbiomes.To our knowledge, this is the first metagenomic study on the microbiome of mangroves in the Red Sea, and the first application of unbiased 454-pyrosequencing to study the rhizosphere microbiome associated with A. marina. Our results provide the first insights into the range of functions and microbial diversity in the rhizosphere and soil sediments of gray mangrove (A. marina) in the Red Sea

Dynamic Use of Closures and Imperfectly Enforced Quotas in a Metapopulation

The dynamic efficiency of closures in bioeconomic systems depends upon stock levels and in situ values that evolve over time, and on relative costs of implementation. A model of a harvested metapopulation is presented in which second-best reduction of harvest from open-access levels using input quotas balances monitoring costs against dynamic benefits of mitigating overharvesting. Temporary or permanent closures—though generally still second best—are preferable to quotas under certain conditions, as demonstrated for a representative patch and time period. Interactions between patches are discussed. Numerical solutions illustrate comparative dynamics of closure use, and show their potential benefits in a dynamic regulatory path. Copyright 2007, Oxford University Press.

Utilization of cotton plant ash and char for removal of 2, 4-dichlorophenoxyacetic acid

Cotton is a common Indian crop grown on a considerable portion of farmland across the country. After separating the useful product (cotton fibers), the other parts of the plant (stalks, leaves, etc.) are discarded as wastes. In most cases, these plant materials are used as fuel in boilers or households. Cotton wastes when ignited in the presence and absence of air produce cotton plant ash (CPA) and cotton plant char (CPC), respectively. However, CPA and CPC produced pose environmental problems such as safe disposal. Thus, there is an urgent need to characterize the physical and chemical properties of these derivatives and to identify their potential uses. This study highlights the potential utilization of CPA and CPC as adsorbents of 2,4-D. The main components in CPA, namely, CaO and K2O, provide micronutrients to the soil and are thus useful as a biofertilizers. Moreover, low manufacturing cost and higher availability favor the use of CPA as an efficient, low-cost adsorbent as well as a potential source of vital micronutrients. The adsorption capacity of CPA and CPC was tested using 2,4 dichlorophenoxyacetic acid (2,4-D) as the representative herbicide. Experimental data were analyzed by Freundlich and Langmuir adsorption isotherms, and these fitted well with the Langmuir model. The adsorption capacity q0 was found to be 0.64 mg/g for CPA and 3.93 mg/g for CPC. Pseudo-first-order pseudo-second-order and intraparticle diffusion kinetic models were applied to experimental data, and the pseudo second order kinetics model showed best fit for the adsorption of 2,4-D on CPA and CPC. Both CPA and CPC were characterized using proximate analysis, SEM images, BET surface area, XRF, FTIR, and CHNS. The BET surface area was found to be 2 and 109 m2/g, respectively, for CPA and CPC. Adsorption study results indicated that both CPA and CPC are very effective cheap adsorbent for 2,4-D removal