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Vinícius dos SANTOS Peter MARSHALL FLEMING Luís HENRIQUE MANCINI Stela DALVA SANTOS COTA Graziele Beatriz de LIMA Rafaela RODRIGUES GOMES Roberto Eduardo KIRCHHEIM Ricardo SANCHéZ-MURILLO Didier GASTMANS 《大气科学进展》2022,39(10):1693-1708
Precipitation isotope ratios (O and H) record the history of water phase transitions and fractionation processes during moisture transport and rainfall formation. Here, we evaluated the isotopic composition of precipitation over the central-southeastern region of Brazil at different timescales. Monthly isotopic compositions were associated with classical effects (rainfall amount, seasonality, and continentality), demonstrating the importance of vapor recirculation processes and different regional atmospheric systems (South American Convergence Zone-SACZ and Cold Fronts-CF). While moisture recycling and regional atmospheric processes may also be observed on a daily timescale, classical effects such as the amount effect were not strongly correlated (δ18O-precipitation rate r ≤ –0.37). Daily variability revealed specific climatic features, such as δ18O depleted values (~ –6‰ to –8‰) during the wet season were associated with strong convective activity and large moisture availability. Daily isotopic analysis revealed the role of different moisture sources and transport effects. Isotope ratios combined with d-excess explain how atmospheric recirculation processes interact with convective activity during rainfall formation processes. Our findings provide a new understanding of rainfall sampling timescales and highlight the importance of water isotopes to decipher key hydrometeorological processes in a complex spatial and temporal context in central-southeastern Brazil. 相似文献
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We classified homogenous river types across Europe and searched for fish metrics qualified to show responses to specific pressures (hydromorphological pressures or water quality pressures) vs. multiple pressures in these river types. We analysed fish taxa lists from 3105 sites in 16 ecoregions and 14 countries. Sites were pre-classified for 15 selected pressures to separate unimpacted from impacted sites. Hierarchical cluster analysis was used to split unimpacted sites into four homogenous river types based on species composition and geographical location. Classification trees were employed to predict associated river types for impacted sites with four environmental variables. We defined a set of 129 candidate fish metrics to select the best reacting metrics for each river type. The candidate metrics represented tolerances/intolerances of species associated with six metric types: habitat, migration, water quality sensitivity, reproduction, trophic level and biodiversity. The results showed that 17 uncorrelated metrics reacted to pressures in the four river types. Metrics responded specifically to water quality pressures and hydromorphological pressures in three river types and to multiple pressures in all river types. Four metrics associated with water quality sensitivity showed a significant reaction in up to three river types, whereas 13 metrics were specific to individual river types. Our results contribute to the better understanding of fish assemblage response to human pressures at a pan-European scale. The results are especially important for European river management and restoration, as it is necessary to uncover underlying processes and effects of human pressures on aquatic communities. 相似文献
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Geslaine Rafaela Lemos Gonçalves Luana Ferraz da Silveira Palomares Aline Nonato Sousa Gilson Stanski Gustavo Sancinetti Rogerio Caetano da Costa Antonio Leão Castilho 《Marine Ecology》2020,41(4):e12606
The Brazilian coast is home to two species of Majoid crabs: Libinia ferreirae and Libinia spinosa, with similar habits, as they live in symbiosis with the jellyfish Lychnorhiza lucerna during their juvenile stage and dwell on the bottom of the ocean near the coast when adults. This study investigated the spatial and temporal distribution of L. ferreirae and L. spinosa during different ontogenic phases on the south and south-eastern coast of Brazil, between latitudes 22º and 27ºS. Our results showed that both species have different distributions during their development in the three studied regions. Libinia ferreirae were more abundant associated with jellyfish, and L. spinosa were more abundant in the free-living phase. Environmental factors, especially temperature and salinity, for associated and free-living crabs, respectively, are the main factors that need to be supported for the establishment of these specimens. We were able to identify that the presence or absence of hosts (given the ecological interactions between the species) is determinant in finding the associated crabs. Geographical variations (morphology of the regions, marine currents and the strength of the tide) are linked directly to the movement of the jellyfish hosts to the coast, influencing the abundance of L. fereirae and L. spinosa populations and affecting their distribution patterns. We can infer that both species are connected with other populations because of the association with the jellyfish, crabs could be passively transported along the south and south-eastern coast of Brazil, maintaining the connection between metapopulations. 相似文献
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Clemens?TrautweinEmail author Rafaela?Schinegger Stefan?Schmutz 《Aquatic Sciences - Research Across Boundaries》2012,74(2):329-341
The catchment land-use composition of 249 fish sampling sites in Austrian running waters revealed effects on the biological
integrity. Beyond correlative analysis, we investigated (1) which land-use category had the strongest effect on fish, (2)
whether metrics of functional fish guilds reacted differently, (3) whether there were cumulative effects of land-use categories,
and (4) whether effects varied in strength across river types. We fed 5 land-use categories into regression trees to predict
the European Fish Index or fish metric of intolerant species (mainly Salmo trutta fario). Agriculture and urbanisation were the best predictors and indicated significant effects at levels of >23.3 and >2%, respectively.
Model performance was R
2 = 0.15 with the Fish Index and R
2 = 0.46 with intolerant species. The tree structure showed a cumulative effect from agriculture and urbanisation. For the
intolerant species metric, a combination of high percentages for agriculture and urbanisation was related to moderate status,
whereas <7.3% agriculture were related to good status, although urbanisation was higher than 1.8%. Headwater river types showed
stronger responses to land use than river types of lower gradient and turned out to be more sensitive to urbanisation than
agriculture. 相似文献
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Dbora Ferreira Barbosa Thelma Lúcia Pereira Dias Srgio de Faria Lopes Rafaela Cristina de Souza Duarte Fernanda Maria Duarte do Amaral 《Marine Ecology》2019,40(5)
This study investigated the community structure and functional traits of the mollusk fauna associated with macroalgae with different thallus morphologies in a reef environment in Northeastern Brazil. A total of 15 individuals of each species of macroalgae adhered to natural substrate and 15 individuals of Padina gymnospora detached from the substrate were collected. The structural complexity of algal habitats was measured and the associated malacofauna screened and identified. All three macroalgae differed significantly in the complexity of their habitat, with Sargassum polyceratium being the most complex. A total of 823 specimens of mollusks belonging to 22 species and 11 families were recorded, of which Columbellidae was the most represented with six species. The functional trait “size” revealed that micromollusks smaller than 10 millimeters were predominant in the community; however, individuals of larger sizes (up to 24.54 millimeters) belonging to young stages of other species were also present. Eight functional trophic groups were identified, of which “carnivorous” stood out with seven species. Six functional groups of microhabitats were identified, with intra‐specific variation in habitats, while habitat expansion was documented for species not yet recorded in association with macroalgae. The structure of the molluskan community differed among the three algae species with the greatest richness, abundance, and diversity of mollusks and functional traits occurring with S. polyceratium. Community structure differed between algae adhered to natural substrate and detached algae, with the latter having lower mollusk richness and diversity, but with greater abundance of some species that remained on algal fronds after release from the reef environment. This study reinforces the importance of algal habitat for marine invertebrate fauna, especially for micromollusks that spend their entire life cycle, or part of it, in association with macroalgae. 相似文献
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Luiz Carlos Cotovicz Junior Eunice da Costa Machado Nilva Brandini Rafaela Cristine Zem Bastiaan Adriaan Knoppers 《Environmental Earth Sciences》2014,72(2):373-386
This study addresses the distribution of total phosphorus (TP) and its inorganic (IP) and organic (OP) fractions, grain-size and organic matter of surface and recent sediments, coupled to the behavior of total and dissolved inorganic phosphorus (TP and DIP) of the water column, of the semi-pristine Guaratuba Bay estuary, SE Brazil. Surface sediment samples were taken at 43 sites spread along the estuarine gradient and recent sediments from 3 short (35 cm long) cores from the upper, central and lower portions of the estuary, respectively. Highest TP and IP concentrations of surface sediments were detected within the upper sector and the transition zone between the upper and central sectors, all characterized by fine sediments, low salinities and water depths. In contrast, the lower sector and its narrow and deep tidal channel, subject to more intense tidal forcing, exhibited a higher fraction of sandy sediments with lower TP, IP and OP contents. In spite of the spatial variability in sediment grain size, IP corresponded to the major fraction of TP in all estuarine sectors and both TP and IP correlated significantly with the fine sedimentary (silt + clay) grain-size fraction. The fine surface sediments acted as a trap for IP at the fresh water–low salinity interface, which also corresponded to the region of a DIP sink in surface waters. In general, the short sediment cores showed that TP and IP contents increased from 15 cm depths to the top layer. Published sedimentation rates from additional cores taken at the sites of the short cores of this study, implied that depositional alterations of TP and IP increased during the early 1970s, which corresponded to the onset of anthropogenic disturbances from crop plantations in the lowland plains of the river end-member and urbanization at the estuary’s mouth and along the adjacent coast. 相似文献
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Barry W. Brook Kingsley Edney Rafaela Hillerbrand Rasmus Karlsson 《Climate Policy》2016,16(6):803-813
We propose that an international ‘Low-Emissions Technology Commitment’ should be incorporated into the United Nations Framework Convention on Climate Change (UNFCCC) negotiation process in order to promote innovation that will enable deep decarbonization. The goal is to accelerate research, development, and demonstration of safe, scalable, and affordable low-emissions energy technologies. Such a commitment should be based on three elements. First, it should operate within existing UNFCCC negotiations so as to encourage developed states to offer directed funding for energy research as part of their national contributions. Second, pledges should be binding, verifiable, and coordinated within an international energy-research plan. Third, expert scientific networks and participating governments should collaborate to design a coordinated global research and technology-demonstration strategy and oversee national research efforts. To this end an Intergovernmental Panel on Low-Emissions Technology Research might be established. This proposal offers some insurance against the risk that the political impasse in international negotiations cannot be overcome. The higher costs associated with low-emissions alternatives to fossil fuels currently creates significant economic and political resistance to their widespread adoption. To breach this impasse, a mechanism supporting accelerated energy research is needed that seeks to reduce future abatement costs, share experience and ‘learning-by-doing’ in first-of-a-kind demonstrations, and thus facilitate future widespread deployments. These actions will also assist in addressing inequalities in energy access.Policy relevanceOver the past decade, global fossil-fuel use and associated carbon emissions have risen steadily, despite the majority of nations agreeing, in principle, to work to limit global warming to less than 2?°C above pre-industrial conditions (IPCC, 2014). Accelerated research, development, and demonstration of low-emissions technologies will be required for successful and economically efficient decarbonization of the global economy, but how can the current deadlock be broken? The UNFCCC does not contain adequate mechanisms to promote increased investment in research, so climate-governance institutions are not capturing the gains that could be achieved through a globally coordinated approach. Here, we outline reform proposals that would enhance both the economic effectiveness of global abatement efforts and the political feasibility of accelerated innovation. 相似文献
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Vicente de P. Rodrigues da Silva Adelgicio F. Belo Filho Vijay P. Singh Rafaela S. Rodrigues Almeida Bernardo B. da Silva Inajá F. de Sousa 《水文科学杂志》2017,62(7):1029-1038
Using the Shannon entropy, the space–time variability of rainfall and streamflow was assessed for daily rainfall and streamflow data for a 10-year period from 189 stations in the northeastern region of Brazil. Mean values of marginal entropy were computed for all observation stations and entropy maps were then constructed for delineating annual and seasonal characteristics of rainfall and streamflow. The Mann-Kendall test was used to evaluate the long-term trend in marginal entropy as well as relative entropy for two sample stations. The marginal entropy values of rainfall and streamflow were higher for locations and periods with the highest amounts of rainfall. The entropy values were higher where rainfall was higher. This was because the probability distributions of rainfall and the resulting streamflow were more uniform and less skewed. The Shannon entropy produced spatial patterns which led to a better understanding of rainfall and streamflow characteristics throughout the northeastern region of Brazil. The total relative entropy indicated that rainfall and streamflow carried the same information content at annual and rainy season time scales. 相似文献
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