Southeastern South America Research Articles

Ocean-atmosphere interactions over the western South Atlantic during Heinrich stadials

Abstract Slowdowns of the Atlantic meridional overturning circulation during Heinrich stadials (HS) caused reductions in cross-equatorial heat transport, southward shifts of the Intertropical Convergence Zone and intensification of precipitation over eastern tropical South America. While these changes are well described, the associated spatial sea surface temperature (SST) patterns are still unclear. Here, we analyze proxy data to assess changes in ocean-atmosphere interactions during HS over the western South Atlantic. Our SST proxy records show contrasting patterns between the tropical (warming) and the subtropical (no change) western South Atlantic during HS. We propose that the distinct SST behavior in the subtropics was associated with the cloud cover effect of the South Atlantic Convergence Zone over the upper ocean.

Multi-model climate projections of the main cyclogenesis hot-spots and associated winds over the eastern coast of South America

In this study, multi-model ensembles are used to understand regional features of future climate trends of cyclones and associated winds in eastern South America. For this, we consider three cyclogenetic hot-spot regions located in south-southeastern Brazil, extreme southern Brazil-Uruguay, and southern Argentina, named, respectively, RG1, RG2 and RG3. The multi-model ensembles consist of four RegCM4 downscalings (RegCM4s) nested in three different global circulation models (GCMs) from CMIP5 under RCP8.5 for the period 1979–2100. ERA-Interim, and CFSR provide the reanalyses ensemble. For the present climate (1979–2005), RegCM4s and GCMs simulate the main characteristics of the cyclone’s genesis and propagation. There is greater agreement between RegCM4s and reanalyses regarding the magnitude and location of stronger winds associated with intense cyclones starting in RG1 and RG2. An important added value is the greater ability of RegCM4s to capture the observed features (phase and amplitude of the annual cycle, intensity, and near surface winds) of cyclogenesis starting in regions away from the boundary domain, such as in RG1 and RG2. In these regions, RegCM4s present smaller (higher) error (correlation) for the frequency of cyclones than GCMs, which improves the representation of cyclones for the whole southwestern South Atlantic domain. RegCM4s are able to simulate in greater agreement with reanalysis than GCMs, the initially stronger cyclones and associated low level winds. For these intense cyclones in the future climate, an intensification of low-level winds off the coast (south-southeast Brazil and south Argentina) and a shift to the south of the upper-level polar jet are projected. Furthermore, there is a clear trend towards decrease in the number of cyclogeneses in each hot-spot region, indicating that each intense cyclone will be associated with stronger low level winds near the eastern South America coast at the end of the twenty-first century.

Species delimitation, environmental cline and phylogeny for a new Neotropical genus of Cryptinae (Ichneumonidae).

A morphologically unusual Cryptini, Cryptoxenodon gen. nov. Supeleto, Santos & Aguiar, is described and illustrated, with a single species, C. metamorphus sp. nov. Supeleto, Santos & Aguiar, apparently occurring in two disjunct populations in northern and southeastern South America. The highly dimorphic female and male are described and illustrated. The phylogenetic relationships of the new genus are investigated using a matrix with 308 other species of Cryptini in 182 genera, based on 109 morphological characters and molecular data from seven loci. The analyses clearly support Cryptoxenodon gen. nov. as a distinct genus, closest to Debilos Townes and Diapetimorpha Viereck. Species limits and definition are investigated, but despite much morphological variation the analyses at the specimen level do not warrant the division of the studied populations into separate species. The considerable morphological variation is explored with principal component analyses of mixed features, and a new procedure is proposed for objective analysis of colors. The relationship of color and structural variation with altitude and latitude is demonstrated and discussed, representing an important case study for Ichneumonidae. Externally, Cryptoxenodon gen. nov. can be recognized mainly by its unusually large mandibles, but other diagnostic features include clypeus wide; sternaulus complete, distinct and crenulate throughout; areolet closed, about as long as pterostigma width; petiole anteriorly with distinct triangular projection on each side, spiracle near posterior 0.25; propodeum without posterior transverse carina; and propodeal apophyses conspicuously projected.

Does Antarctic Oscillation have links and influence precipitation over the Uruguay River Drainage Basin in Southeastern South America?

AbstractThis article examines the links and the influence of Antarctic Oscillation (AAO) on precipitation over the Uruguay River Drainage Basin and adjacent regions, situated in Southeastern South America. In this article, we used monthly data of AAO Index obtained from the Climate Prediction Center/National Centers for Environmental Prediction (CPC/NCEP); monthly data of 500 hPa vertical motion through omega variable (ω = Dp/Dt) and converted to vertical velocity (cm/s) from the NCEP/NCAR Reanalysis; monthly data of precipitation from the NCEP Reanalysis 2 and monthly data of precipitation rate from the CPC Merged Analysis of Precipitation (CMAP) with a latitude × longitude spatial resolution of 2.5° × 2.5°. All data are monthly means and were obtained from January 1979 to December 2008. The methodological procedures used Grid Analysis and Display System (GrADS) software to generate composites of vertical motion and precipitation rates. In the case of CMAP precipitation data, the methodology consists of applying the Aspin Welch statistical test, which verifies the statistical significance of the difference between two means using a significance level of 5%. The study region indicates a tendency to present higher (lower) mean rates of precipitation during the AAO negative (positive) phase. The vertical motion analysis results corroborate with the precipitation rates since the higher vertical motions were found during the negative phase of AAO. The statistical test showed, to some areas of Uruguay River Drainage Basin and adjacent regions, statistically significant differences between mean rates of precipitation observed in both phases of AAO.

Novelties in Brazilian Waltheria L. (Byttnerioideae, Malvaceae): two new species and one re-establishment

This work validates two Waltheria species endemic to campo rupestre with complete descriptions, illustrations, updated geographical distributions and comments on taxonomic affinities. Waltheria biribiriensis and Waltheria terminans are restricted to the Southern Espinhaço Province in eastern South America, occurring on mountain tops where campo rupestre vegetation prevails. Furthermore, Waltheria brachypetala, a species of dry deciduous forests in Brazil that was long considered as conspecific with W. ferruginea due to its shrubby lifeform and similar indumentum, is re-established based on differences of phyllotaxy, blade shape and inflorescence type. The first occurrence records of W. brachypetala in the state of Paraíba are also provided, as well as the first record in the Atlantic Forest domain. Lastly, a lectotype is designated for W. ferruginea.

Amazon river plume influence on planktonic decapods in the tropical Atlantic

The western tropical Atlantic is strongly influenced by the Amazon, receiving the full discharge from the largest river basin of the world. In order to ascertain the coastal-oceanic gradient in abundance and composition of planktonic decapod communities along the Amazon River Plume (ARP) and its retroflection, 33 plankton samples were obtained along three sampling transects: Coastal and oceanic area influenced by the ARP (Coastal IARP and Ocean IARP, respectively), and oceanic waters without ARP influence (Ocean). A total of 13,117 specimens, belonging to 33 taxa, were analyzed. The distribution of planktonic decapod communities was strongly influenced by the Amazon discharge, showing the following patterns: (1) The coastal-oceanic gradients in decapod abundance are similar to other shelf areas of eastern South America, with higher abundance in the area under ARP influence, (2) meroplanktonic decapods dominate in coastal and some oceanic areas due to the offshore transport of coastal organisms along the ARP retroflection, and (3) the ARP is clearly responsible for the observed differences in community structure between the three transects. Furthermore, this study highlights the importance of coastal and shelf environments as main sources of planktonic decapods for pelagic ecosystems in the tropical Atlantic during the period of strong North Brazil Current retroflection.

Spatial and temporal variability of daily precipitation concentration in southeastern South America

AbstractThe study of the spatial and temporal variability of the precipitation concentration is necessary, due to its high environmental and socioeconomic impact. For this reason, this study aims to contribute to the knowledge of daily rainfall in southeastern South America. Daily records of precipitation for 48 stations are used (period 1979–2018) to calculate the concentration index (CI). High CI is linked to rapid physical processes such as convection, and low CI can be interpreted as a consequence of regular patterns such as the continuous passage of fronts. The spatial and temporal distribution of CI brings information about frequency and changes in heavy rainfall days. The spatial distribution of the CI at an annual level has a range of variation between 0.54 and 0.68. The CI temporal variation shows different regional behaviour. In Brazil, there is an increase in the CI, while in Uruguay and the north‐central part of Argentina negative trends are present in the four seasons.

Spatio-temporal soil drying in southeastern South America: the importance of effective sampling frequency and observational errors on drydown time scale estimates

ABSTRACT The study of the spatio-temporal dynamics of surface soil moisture (SSM) drydowns integrates the soil response to climatic conditions, drainage and land cover and is key to advances in our knowledge of the soil–atmosphere water exchange. SSM drydowns have also been employed to compare soil moisture spatio-temporal behaviour between different data sources such as satellite-derived data and land–surface models, difficult to compare with standard methodologies. However, the errors introduced by satellite effective sampling frequencies (SF) and by different methodologies employed to define a drydown period have until now not been properly addressed in the literature. Here, SSM from microwave remote sensing products operating at L, C and X frequency bands are analysed together with SSM from a land–surface model in southeastern South America during 2010–2014, at seasonal and annual scales. We use an SSM-based drydown detection methodology and an exponential model to estimate the drydown time scale. The errors generated by the SF and by using SSM instead of precipitation to define the start of the drydown period are examined using a synthetic soil moisture model. Most of the products can detect the negative correlation between aridity conditions and drydown time scales (faster soil drying in the semiarid west and slower – and noisier – towards the wetter east). The Soil Moisture Ocean Salinity (SMOS) L-band product reproduces the smoothest drydown time scale spatial patterns at the annual and seasonal scales and displays large seasonal contrasts, although its error due to SF is the highest among the three products. The Organizing Carbon Hydrology In Dynamic Ecosystems (ORCHIDEE) land–surface model resampled by the SF of each product shows better agreement with SMOS, followed by the X-band product. The agreement is higher over the southern Pampas Plains, a region with high coverage of satellite-derived data and flat topography. SSM observational errors generate higher relative uncertainties for drydown time scales longer than 8 days, while the SF is more relevant for shorter drydowns. Also, the SF has a larger impact than soil depth, particularly in the dry season, when sparse temporal coverage misses short drydowns. Soil texture influence is captured by SMOS and ORCHIDEE, revealing slower drydowns for finer textures at the annual scale. Our results show that the soil drying behaviour is comparable between microwave remote sensing products and a land–surface model and that the observational errors and the SF are important sources of uncertainty to consider when interpreting drydown results.

Assessment of ECMWF Subseasonal Temperature Predictions for an Anomalously Cold Week Followed by an Anomalously Warm Week in Central and Southeastern South America during July 2017

AbstractThe demand of subseasonal predictions (from one to about four weeks in advance) has been considerably increasing as these predictions can potentially help prepare for the occurrence of high-impact events such as heat or cold waves that affect both social and economic activities. This study aims to assess the subseasonal temperature prediction quality of the European Centre for Medium-Range Weather Forecasts (ECMWF) against the Japan Meteorological Agency reanalyses. Two consecutive weeks of July 2017 were analyzed, which presented anomalously cold and warm conditions over central South America. The quality of 20 years of hindcasts for the two investigated weeks was compared to that for similar weeks during the JJA season and of 3 years of real-time forecasts for the same season. Anomalously cold temperatures observed during the week of 17–23 July 2017 were well predicted one week in advance. Moreover, the warm anomalies observed during the following week of 24–30 July 2017 were well predicted two weeks in advance. Higher linear association and discrimination (ability to distinguish events from nonevents), but reduced reliability, was found for the 20 years of hindcasts for the target week than for the hindcasts produced for all of the JJA season. In addition, the real-time forecasts showed generally better performance over some regions of South America than the hindcasts. The assessment provides robust evidence about temperature prediction quality to build confidence in regional subseasonal forecasts as well as to identify regions in which the predictions have better performance.

Systematic Revision of Papillaria (Meteoriaceae, Bryophyta)

Abstract—A systematic revision of the tropical moss genus Papillaria was carried out by combining morphological studies with phylogenetic reconstructions based on molecular data from the plastid (trnL-F and rpl16) and the nuclear (ITS region) genomes. For the morphological study a set of qualitative and quantitative features was studied in over 2800 herbarium specimens, including the types, of all 55 previously accepted species in the genus. After revision, nine species of Papillaria were recognized, Papillaria crocea and P. flexicaulis which are broadly distributed in the tropics, P. africana that is endemic to Africa, P. laevifolia that is known from the Americas, and P. flavolimbata, P. funiformis, P. leuconeura, P. nitens, and P. zeloflexicaulis that are known from Australia and the Pacific Islands. The majority of the other previously accepted names do not belong to Papillaria s. s. but to the closely related genera Toloxis and Meteorium. We propose five new synonyms under P. africana as well as one new synonym for P. crocea and one for P. laevifolia. The revision reduced the number of Papillaria species in Africa from ten to one and in South America from thirteen to three. We extend the geographic range of P. crocea due to a new record from eastern South America (Brazil).

The impact of soil moisture–atmosphere coupling on daily maximum surface temperatures in Southeastern South America

Based on a series of experiments conducted by two regional climate models (RCA4 and LMDZ) with and without soil moisture-atmosphere coupling, we investigate the role of soil moisture on the occurrence of surface air temperature extremes and its persistence in Southeastern South America. Our analysis reveals that both factors, soil moisture-atmosphere coupling and relatively drier soil conditions, enhance the temperature extremes. In addition, the existence of soil-atmosphere coupling and the associated soil moisture variability is crucial for the development of the extremes in SESA. The key role of soil-atmosphere coupling is also reflected in the intrinsic persistence of hot days, which is greater in simulations with interactive soil moisture than in those with prescribed soil conditions. In the absence of soil-atmosphere coupling, the imprint of the anomalous dry (and also wet) soil conditions on the intensity and persistence of hot days is weaker.

A new proposal for the technological analysis of lithic points: Application for understanding the cultural diversity of hunter gatherers in Eastern South America

The lack of a standard protocol for analyzing and comparing multiple assemblages of lithic artifacts has hindered the advance of a better understanding of the cultural diversity associated to prehistoric hunter-gatherer groups. This was the case of Brazilian archaeologists that for many decades associated lithic stemmed point assemblages to a cultural entity known as “Umbu Tradition”. However, most associations of assemblages to this “tradition” have been made regardless of the type of lithic points, as well as ignoring other elements related to the lithic industry, settlement patterns, among others. As a result, since the 1980s, several studies have been questioning the validity of such Tradition. Recent research has proposed new definitions for the previously associated Umbu Tradition lithic industries based on the stemmed points typology. However, no raw data on the technological analysis of such points have ever been presented. This article proposes a protocol for the technological study of lithic points that allows the application of descriptive statistics and multivariate analysis to verify if these types present or not significant differences. We present new data on the technological analysis of 501 lithic points from sites located in the supposed Umbu Tradition coverage area and period, as well two new Early Holocene C14 dates for one of the studied sites (Caetetuba site). Our results corroborate previous propositions of discarding Umbu Tradition as a valid cultural entity, as well as new typologies for the points. We also show that our protocol is suitable to unravel potential cultural patterns regarding many attributes in lithic points as well as to explore if there are significant differences among previously defined types.

A new fossil cricetid (Rodentia, Sigmodontinae) from northeastern Brazil with remarks on small mammal extinctions in the tropical Quaternary

AbstractThe rare cricetid rodent Bibimys Massoia, 1980 contains three extant species that are distributed in the lowlands of eastern South America between 35°S and 20°S and distinguished mostly by subtle morphological and genetic features. Several fragmented jaws belonging to this genus were recovered from Late Quaternary deposits located in northeastern Brazil, forming part of a rich archaeological and paleontological small mammal assemblage that has been recovered from caves in the Serra da Capivara, state of Piauí. This material is described herein as belonging to a new species, the most hypsodont member of the genus. The specimens also represent an extralimital occurrence of this sigmodontine, as the nearest extant population of Bibimys is ~1,200 km to the south. Because there are few reliable records of extinct small mammals from the Pleistocene–Holocene transition on the South American continent, in describing this new sigmodontine we extend the records of past biodiversity preserved in the Quaternary deposits of tropical South America. This new species likewise highlights that the Serra da Capivara deposits are promising for understanding the evolutionary history of cricetid rodents.

A New Lungfish from the Jurassic of Thailand

The lungfishes, or Dipnoi, form a depauperate clade of sarcopterygian fishes living today in the freshwater systems of eastern Australia, Africa, and South America. Lungfishes were mostly marine in...

Poor availability of context-specific evidence hampers decision-making in conservation

Evidence-based conservation relies on reliable and relevant evidence. Practitioners often prefer locally relevant studies whose results are more likely to be transferable to the context of planned conservation interventions. To quantify the availability of relevant evidence for amphibian and bird conservation we reviewed Conservation Evidence, a database of quantitative tests of conservation interventions. Studies were geographically clustered, and few locally conducted studies were found in Western sub-Saharan Africa, Russia, South East Asia, and Eastern South America. Globally there were extremely low densities of studies per intervention - fewer than one study within 2000 km of a given location. The availability of relevant evidence was extremely low when we restricted studies to those studying biomes or taxonomic orders containing high percentages of threatened species, compared to the most frequently studied biomes and taxonomic orders. Further constraining the evidence by study design showed that only 17–20% of amphibian and bird studies used reliable designs. Our results highlight the paucity of evidence on the effectiveness of conservation interventions, and the disparity in evidence for local contexts that are frequently studied and those where conservation needs are greatest. Addressing the serious global shortfall in context-specific evidence requires a step change in the frequency of testing conservation interventions, greater use of reliable study designs and standardized metrics, and methodological advances to analyze patchy evidence bases.

Atmospheric circulation influence on temperature and precipitation individual and compound daily extreme events: Spatial variability and trends over southern South America

Southern South America (SSA) is an extended region where temperature and precipitation daily extreme events have several impacts on the different socio-economic activities. In this work, their individual and compound occurrence over SSA and their association with atmospheric circulation were studied during 1979–2015, using meteorological stations and the CPC gridded dataset. Results were generally in good agreement between both datasets. The occurrence of a warm night (minimum temperature exceeding the 90th percentile) or a cold day (maximum temperature below the 10th percentile) significantly increases the probability of heavy precipitation (daily precipitation exceeding the 75th percentile) in southern Chile and southeastern South America. These compound events were regionally conditioned by specific circulation types. In addition, both individual and compound extremes showed trends in the different sub-regions. On one hand, heavy precipitation exhibited a significant increase over central-eastern Argentina and Uruguay, northeastern Argentina and southern Brazil during the warm season, and a significant decrease in central and southern Chile during the cold season. On the other hand, warm (cold) extremes generally presented significant upward (downward) trends. Compound events showed significant positive trends for selected regions, in some cases coincident with trends in individual extremes. Changes in the frequency of circulation patterns were found to partly influence some of these trends, like the increases in heavy precipitation and warm extremes during the warm season.

Assessment of South America summer rainfall climatology and trends in a set of global climate models large ensembles

AbstractThe purpose of this study is to assess the ability of a set of large ensembles (LE) of Global Climate Model (GCM) simulations from the Multi‐Model Large Ensemble Archive, Coupled Model Intercomparison Project Phase 6 (CMIP6) and database for Policy Decision making for Future climate change in reproducing the variability and change of the austral summer precipitation observed in South America along the second part of the 20th century and beginning of the 21st. LE show similar biases in the mean austral summer rainfall and interannual variability than those detected in previous model sets, such as the Coupled Model Intercomparison Project Phase 5 (CMIP5). The positive trends in south‐eastern South America (SESA) and negative ones in the southern Andes (SAn), that are the most significant observed regional features, are identified to some extent in LE simulations. The negative trend in SAn is a feature consistently shown among different models. For all models, mean trend is negative in that particular region and larger than the inter‐member dispersion for each large ensemble. Trend magnitudes in the SESA region show a larger dispersion between models than the SAn region. While the mean trend among models is consistent with the observations, models underestimate the observed trend. The multi‐model ensemble of selected models that best reproduce both mean and interannual variability features of rainfall in South America shows an 18% larger positive mean trend in SESA rainfall than those that have the worst performance. However, internal variability uncertainty is still higher than the mean trend for both sets of multi‐model ensembles [5% (18%) for selected (non‐selected) models]. Improvements in the representation of the main features of mean rainfall and variability are needed in order to better describe and reduce the uncertainties associated with the main climate change related signals in the continent.

Solar irradiation regionalization in Uruguay: Understanding the interannual variability and its relation to El Niño climatic phenomena

Abstract A regionalization of different characteristics of the solar resource is performed for Uruguay and surrounding areas (Southeastern South America). The input information consists of daily satellite estimates of Global Horizontal Irradiation (GHI) generated in a regular grid using a low uncertainty empirical satellite-based model which was specifically adapted for the region. Clusters are derived from the climatological annual cycle of monthly irradiation and clearness index and, separately, from time-series of monthly variability. The solar irradiation variability in each cluster is compared with El Nino South Oscillation (ENSO) signal. A high negative correlation is observed between ENSO and solar irradiance, most predominantly over February to May and November to December, particularly for the latter. This means that in a strong El Nino/La Nina year, solar irradiation values for the November–December period in Uruguay will be smaller/higher than the climatological average. These results are in agreement with the ones obtained for rainfall in other studies.

Influencia del proceso de aculturación en la percepción de riesgos psicosociales en el trabajo

ObjectiveThe objectives of this study were to analyze the relationships between acculturation strategies and psychosocial risk factors, the acculturative stress and the psychosocial risks, and to assess whether there are differences in acculturative stress depending on the activity sector. Material and methodsThe sample consisted of 201 migrant workers living in the Community of Madrid (49%). Most of them were originally from countries from Eastern Europe and South America. Using a cross-sectional design, we applied Relative Acculturation Extended Model (MAAR) questionnaire to measure acculturation strategies; Barcelona Immigrant Stress Scale (BISS) was applied to measure acculturative stress and psychosocial risks were assessed through the DECORE questionnaire. ResultsThe results showed that there are no statistically significant differences in the strategy used by men and women for each area of acculturation. Participants who used the Marginalization strategy perceived their salary as being low while those who adopted the Intermediate strategy perceived little control over their work. Those who adopted the Integration strategy perceive more work demands (higher job content). Acculturative stress is a predictor of adverse perception of work environment (low control, low rewards and low social support). On the other hand, older workers perceive more control over their work and employees in the home services sector have higher scores in Nostalgia and Psychosocial Stress than those in other sectors. ConclusionsWithin organizations, measures must be put in place to minimize acculturative stress, promote the integration of the workers and improve their perception of psychosocial work factors.

Ecological Dynamics Impacting Bluetongue Virus Transmission in North America.

Bluetongue virus (BTV) is an arbovirus transmitted to domestic and wild ruminants by certain species of Culicoides midges. The disease resulting from infection with BTV is economically important and can influence international trade and movement of livestock, the economics of livestock production, and animal welfare. Recent changes in the epidemiology of Culicoides-transmitted viruses, notably the emergence of exotic BTV genotypes in Europe, have demonstrated the devastating economic consequences of BTV epizootics and the complex nature of transmission across host-vector landscapes. Incursions of novel BTV serotypes into historically enzootic countries or regions, including the southeastern United States (US), Israel, Australia, and South America, have also occurred, suggesting diverse pathways for the transmission of these viruses. The abundance of BTV strains and multiple reassortant viruses circulating in Europe and the US in recent years demonstrates considerable genetic diversity of BTV strains and implies a history of reassortment events within the respective regions. While a great deal of emphasis is rightly placed on understanding the epidemiology and emergence of BTV beyond its natural ecosystem, the ecological contexts in which BTV maintains an enzootic cycle may also be of great significance. This review focuses on describing our current knowledge of ecological factors driving BTV transmission in North America. Information presented in this review can help inform future studies that may elucidate factors that are relevant to longstanding and emerging challenges associated with prevention of this disease.