Montagem De Comunidades: Conceitos, Domínio E Estrutura Teórica

Community assembly refers to any ecological process that operates to select species from a regional pool and put them together in local communities. Initially, Diamond (1975) proposed a community assembly model based on rules explaining the checkerboard distribution of co-occurring bird species in New Guinea archipelago. By that time, the assembly rules proposed interspecific competition as the only plausible explanation for the patterns observed. However, the lack of testable predictions, inappropriate statistical analyses and, mainly, the absence of alternative hypotheses have represented an obstacle for the theory development. With the introduction of phylogenetic/functional analyses in community studies, a meaningful increase of published papers on community assembly has been noticed, mainly due to the development of models providing more predictive power to assembly processes. Hence, we decided to elaborate a critical review about the conceptual progress in the community assembly theory. We point out that a) the community assembly theory has enhanced its predictive power when it became to be associated with solid statistics; b) the hypothesis test by null models has been reinforced as a consistent data analysis method applied in many studies; and c) the neutral theory has been used as a satisfactory alternative to the coexistence hypothesis by deterministic niche-based processes. However, the community assembly theory is not fully mature yet but has a high potential of near-future development, mainly through the consolidation of its conceptual base. We hope that our review can help in this development by systematizing the community assembly theory and clarifying some misunderstood and/or so-far poorly applied concepts. © 2016, Universidade Federal do Rio de Janeiro (UFRJ). All rights reserved.20111

Water use in the São Francisco River basin, Brazil: an interregional input-output analysis

The planning and management of water resources aiming to a sustainable development must necessary pass through a series of studies that will reveal the interrelations and links among economic activities, and if one is considering that there is a set regions involved in the process, the direct and indirect regional interdependencies. Increasing demands of water-use for industrial, agricultural and urban sectors may became very competitive and can result in conflicts among multiple users. In the case of the São Francisco River Basin, Brazil, consisting of a wide-range five states - most of them having drought problems - the water in the basin plays an essential role and any activity in this area has to consider the effects of the water use in the intersectoral and interregional economic relations. Considering the three main states in the basin - Minas Gerais, Bahia and Pernambuco - an interregional input-output system for the economy and for the water flows was constructed by the authors. The above interregional system is then used to analyze the interregional and intersectoral dependencies among the states and the economic activities on the São Francisco river basin area and their relations with the use of water

Water use in the São Francisco River basin, Brazil: an interregional input-output analysis

The planning and management of water resources aiming to a sustainable development must necessary pass through a series of studies that will reveal the interrelations and links among economic activities, and if one is considering that there is a set regions involved in the process, the direct and indirect regional interdependencies. Increasing demands of water-use for industrial, agricultural and urban sectors may became very competitive and can result in conflicts among multiple users. In the case of the São Francisco River Basin, Brazil, consisting of a wide-range five states - most of them having drought problems - the water in the basin plays an essential role and any activity in this area has to consider the effects of the water use in the intersectoral and interregional economic relations. Considering the three main states in the basin - Minas Gerais, Bahia and Pernambuco - an interregional input-output system for the economy and for the water flows was constructed by the authors. The above interregional system is then used to analyze the interregional and intersectoral dependencies among the states and the economic activities on the São Francisco river basin area and their relations with the use of water

Bacterial and microeukaryotic plankton communities in a semi-intensive aquaculture system of sea bass (Dicentrarchus labrax): a seasonal survey

The importance of microbial diversity and their role in the maintenance of fish health in aquaculture systems has been increasingly recognized in recent years. However, there is still a major knowledge gap regarding the ecology, composition and dynamics of microbial plankton assemblages during fish production. In this study, we aimed to investigate the seasonal dynamics and potential interactions of bacterial and microeukaryotic plankton communities in a semi-intensive aquaculture for European sea bass (Dicentrarchus labrax) cultured together with low density of gilthead sea bream (Sparus aurata) over a one-year period (January/2014 – November/2014). While the most abundant bacterial classes were Gammaproteobacteria, Flavobacteriia and Alphaproteobacteria; microeukaryotic communities were dominated by Ochrophyta, Chlorophyta and Ciliophora groups. Temperature and salinity were identified as significant drivers of the overall microbial community composition, which varied congruently along the seasons. However, while the dominant (more abundant) groups of bacteria occurred in the warmest months, the dominant groups of microeukaryotes occurred in the coldest months. There was also an inverse relationship between abundances of grazers and bacterial operational taxonomic units (OTUs). Overall, besides the potential effects of the abiotic parameters on the microbial plankton communities, the correlation between bacteria and microeukaryotic populations observed here may be an indication of trophic and/or metabolic interdependence between these two domains. Future studies should focus on the underlying mechanisms of this interdependence for a better understand of the impact of microeukaryotic communities on aquaculture bacterioplankton structure and function. In addition, this knowledge could be of interest in the development of microbial management strategies for aquaculture systems.publishe

Percolation model for structural phase transitions in Li1−x_{1-x}Hx_xIO3_3 mixed crystals

A percolation model is proposed to explain the structural phase transitions found in Li$_{1-x}$H$_x$IO$_3$ mixed crystals as a function of the concentration parameter $x$. The percolation thresholds are obtained from Monte Carlo simulations on the specific lattices occupied by lithium atoms and hydrogen bonds. The theoretical results strongly suggest that percolating lithium vacancies and hydrogen bonds are indeed responsible for the solid solution observed in the experimental range $0.22 < x < 0.36$.Comment: 4 pages, 2 figure