Review of range extensions of tropical brachyuran crabs into temperate waters of southern Africa

We compiled known occurrence records of seven species of crabs identified in the literature and one documented in this report as having undergone range extensions in southern Africa. Of these eight species, six (Austruca occidentalis, Neosarmatium africanum, Ocypode ceratophthalmus, Portunus segnis, Tubuca urvillei, and Varuna litterata) have extended their ranges either across a major biogeographic boundary that separates the subtropical and warm temperate ecoregions of this coast, or into estuaries that historically lack mangrove forests. For the seventh and eighth species, Charybdis smithii and Scylla serrata, we were unable to find any distributional data that supported poleward range extension. In addition, we contribute the first record of the blue swimming crab, P. segnis, from the temperate south coast of South Africa. This early detection is likely to be part of an ongoing regional trend of tropical-adapted brachyuran crab species extending their ranges into temperate ecoregions.

Dinâmica de ocupação e passivos ambientais nos assentamentos rurais do município de Goiás-GO

Estudos sobre a influência de assentamentos rurais no processo de desmatamento são normalmente controversos. Alguns apontam uma aceleração desse processo, enquanto outros demonstram que nesses locais a dinâmica de uso do solo segue uma tendência regional. No Cerrado (a savana brasileira) esse é um fenômeno ainda pouco conhecido. Nosso objetivo foi analisar o uso e a cobertura do solo em assentamentos rurais do município de Goiás – região com grande destaque nacional –, com foco nas áreas de preservação permanente (APPs) de cursos d’água. Foram empregadas técnicas de geoprocessamento e classificação de imagens de satélites para quatro anos (1985, 1991, 1995 e 2018), com abrangência temporal de 33 anos. Para verificar o padrão do uso do solo em áreas dentro e fora de APPs, nos assentamentos rurais e no restante do município, foram empregadas análises de componentes principais. Os resultados indicam que as áreas com vegetação nativa reduziram em 33% e 34%, para os assentamentos e o restante do município, respectivamente. As classes ligadas às atividades agropecuárias tiveram aumento entre o ano inicial e final do estudo. A ocupação do solo por atividades agropecuárias, dentro das áreas de preservação permanente, teve uma maior redução nos assentamentos. Concluímos que as dinâmicas do uso e ocupação do solo nos assentamentos e no restante do município seguem uma tendência parecida, porém com um atendimento ao código florestal ligeiramente maior nos assentamentos, representando uma maior conservação relativa de áreas nativas do Cerrado. Dynamics of occupation and environmental liabilities in rural settlements in the municipality of Goiás, Goiás A B S T R A C TStudies are controversial about the influence of the implantation of rural settlements in the deforestation process, some point that there is an acceleration of this process, others already show that in these places the dynamics of land use follows a regional trend. In the Cerrado (the Brazilian savannah) this is still a little-known phenomenon. Our objective was to analyze land use and cover in rural settlements and for the municipality of Goiás, where they are located, with a focus on permanent preservation areas (APPs) of water courses. Geoprocessing and satellite image classification techniques were used for four years (1985, 1991, 1995 and 2018), with a time span of 33 years. To check the pattern of land use in areas inside and outside APPs, in rural settlements and in the rest of the municipality, principal component analyzes were used. The results show that the areas with native vegetation reduced by 33% and 34%, for the settlements and the rest of the municipality, respectively. The classes linked to agricultural activities had an increase between the initial and final year of the study. The occupation of the land by agricultural activities, within the areas of permanent preservation, had a greater reduction in the settlements. We conclude that the dynamics of land use and occupation in the settlements and in the rest of the municipality follow a similar trend, it cannot be said that the settlements are responsible for a greater deforestation of native areas of the Cerrado.Keywords: deforestation, Cerrado, geoprocessing, land use.

Geometry of alpine overdeepenings assessed with gravimetry and 3-D modelling

<p>Interpretations of the processes leading to the formation of overdeepened valleys, where the bedrock lies well below sea level today, are contested as the overdeepenings have been filled by sediments or host lakes making observations difficult. Here, we combine gravimetric, GNSS (Global Navigation Satellite System) and borehole data within a 3D forward modelling framework (Gravi3D) to assess the 3-D subsurface geometry of such overdeepenings in the Swiss plateau, to the North of the Alps. Gravi3D has two components (PRISMA and BGPoly), which allow to obtain analytically the gravity effect of prisms and polygons (Nagy (1966) and Talwani & Ewing (1960)). PRISMA allows first to estimate the spatial extent of an overdeepening and the density contrast between the overdeepening fill and the bedrock. In contrast, BGPoly is designed to disclose the details of a complex 3-D geometry of an overdeepening fill through an approximation of its shape with polygons. Gravi3D will be open access and is designed for a larger scientific community.</p><p> <br>Here, we focus on overdeepenings beneath two valleys, the Aare valley and the Gürbe valley to the South of Bern. In this region, the occurrence of overdeepenings has already been disclosed through drilling, but the details about the geometry have not been elaborated yet. The study region is characterized by three mountain ranges oriented North-South and comprises Burdigalian Upper Marine Molasse bedrock. The Gürbe and Aare valleys in-between are c. 300 m-deep and c. 1 km-wide, where overdeepenings with a >100 m-thick Quaternary fill have already been identified by drilling. The gravity data collected along an 8 km-long profile with stations spaced between 100 and 300 m yield a Bouguer anomaly that ranges from c. -99 to -106 mGal. We relate this anomaly to the regional trend (c. 2 mGal over 8 km) and to the effect of the overdeepenings’ sedimentary fillings (2 – 4 mGal/km), disclosing a sharp anomaly pattern over the inferred tunnel valleys. The removal of the signal related to the regional trend results in a residual anomaly of c. 1 mGal for the bedrock ridge in-between the valleys (Belpberg mountain), and of -2.65 and -3.56 mGal for the Gürbe and Aare valley overdeepenings, respectively. We observe a steeper gravity gradient for the Eastern flank of both overdeepenings. The use of Nettleton method to model the residual gravity anomaly across Belpberg yields a density of 2.5 g/cm<sup>3</sup> for the Molasse bedrock. In addition, the estimation of the largest gravity response through the overdeepening fill, calculated with Prisma yields a density value of c. 2.0 – 2.2 g/cm3 for the Quaternary sediments. As a further information, Prisma predicts a maximum thickness of 140 m for the Quaternary suite beneath the Gürbe valley and at least 200 m beneath the Aare valley. This yields a minimum slope of approximately 18° for the Gürbe overdeepening.</p><p> </p><p>REFERENCES</p><p>Nagy, D.: The gravitational attraction of a right rectangular prism. Geophysics 31, 362–371, 1966.</p><p>Talwani, M., Ewing, M.: Rapid computation of gravitational attraction of three‐dimensional bodies of arbitrary shape. Geophysics 25, 203–225, 1960.</p>

Regional trends in flood quantiles across Europe between 1960 and 2010

<p>Evidence of past flood regime changes in Europe has been shown by several local and regional trend detection studies. These studies typically analysed changes in the mean or median flood. In this work, we investigate regional trends in the 2-year flood and in the 100-year flood. Additionally, it is of interest to investigate the effect of catchment scale on the changes in time of the selected flood quantiles. We analyse 2370 flood records, selected from a newly available pan-European flood database, with record lengths of at least 40 years over the period 1960-2010 and catchment areas ranging from 5 to 100 000 km<sup>2</sup>. In order to estimate the regional trend in flood quantiles, a non-stationary regional flood frequency approach is used, consisting of a regional Gumbel distribution whose parameters are allowed to vary with time and with catchment area. A Bayesian Markov Chain Monte Carlo (MCMC) approach is used for parameter estimation. With a spatial moving window approach, regional trends of the selected flood quantiles, and the related uncertainties, are estimated and compared across Europe, for hypothetical catchment sizes ranging from 10 to 100 000 km<sup>2</sup>. Distinctive patterns of flood regime change are identified for large regions across Europe which depend on flood magnitudes and catchment areas. The resulting trends in flood magnitudes are positive (with the exception of very large catchments) in Atlantic catchments, where the magnitude of trends decreases with increasing catchment size and for bigger return periods. In Mediterranean catchments the regional trends are negative, with small floods experiencing a stronger decrease than large floods. In Eastern European catchments, the regional trends are clearly negative, with larger magnitudes (in absolute value) for larger catchments; they do not appear to vary substantially with the return period.</p>

Overdeepenings modelled with gravimetry-based data

<p>The processes and mechanisms resulting in overdeepenings, valleys carved deeper than today’s rivers base level during glaciations, are still a matter of debate. Whether or not these valleys formation is due to glacial or fluvio-glacial processes or through fluvial down cutting in the geological past is difficult to affirm, as the depressions are filled with sediment or host lakes (Cook and Swift, 2012). In order to bypass this limitation, we use precise gravimetric data, GNSS data and borehole data, which we combine within a 3D forward modelling code, Gravi3D. We particularly aim at reconstructing the geometry of overdeepened valleys’ walls, which bear information on the erosional mechanism leading to the formation of these troughs. We proceed through the building of models for a given geometry to reproduce the Bouguer gravity that we measured in the field along sections and on a grid of stations. We constrain our models by using precise density values, determined by gravimetry, along with borehole data.</p><p>We apply this technique to overdeepenings located in the Alpine foreland (Belpberg area, Central Switzerland) because this area hosts multiple overdeepenings from the past glaciations. The region is characterized by three hill ranges made up of Molasse bedrock with c. 300 m-deep and c. 1 km-wide valleys in-between, where overdeepenings with a Quaternary infill are expected. The results of gravity data collection, accomplished over a section with stations spaced between 100 and 300 m and after standard corrections yield a Bouguer anomaly for the Belpberg region that ranges from c. -99 to -106 mgal. We infer this large range to the regional trend (c. 2 mgal over 8 km) and to the effect of the overdeepening infill (2-4 mgal over 1 km), disclosing a sharp anomaly pattern over the inferred overdeeping. The subsequent three steps include: (i) the removal of the regional trend, (ii) the use of the Nettleton method for the quantification of an accurate density contrast between the Molasse bedrock and the Quaternary infill, and (iii) the configuration of Gravi3D for the Belpberg situation, will yield further information on the morphology of the overdeeping. We thus conclude that Gravi3D, within this framework, is a useful tool to determine the geometry of overdeepings in particular, and shallow subsurface bodies and structures in general.</p><p>Reference:</p><p>Cook, S.J., Swift, D.A., 2012. Subglacial basins: Their origin and importance in glacial systems and landscapes. Earth-Science Reviews 115, 332–372.</p>

La escuela secundaria frente al desafío de la universalización: Debates y experiencias en Argentina

In 2006 Argentina established compulsory secondary schooling, joining the regional trend. During that process a significant debate was developed about whether the school is universalizable with the characteristics that it currently presents, the product of a long historical process that has consolidated a functioning matrix. Does the school present the characteristics that make it feasible to successfully cover all social classes, all cultures, and all school trajectories? This debate focuses on speeches about inclusion within a country that had promoted an egalitarian school system since its inception, building an equivalence between equality, inclusion and homogeneity. The durability of this discourse and how the consecrated school format– in school everyday life and in the social image – is an obstacle in itself for the universalization of schooling. This configuration was very productive in that system, even though it was not exempt from the stratification and class bias marking school culture that has assumed in other countries. This article summarizes some axes of that debate produced in the last decade in Argentina. We present two new school modalities – one as an initiative of specific educational policies and the another as a result of autonomous community processes – that have developed innovative institutional formats to make possible the schooling of diverse school populations.