RESUMO
To protect ecosystems impacted by human activities and prevent their degradation, it is imperative to evaluate variations in the concentration of environmental pollutants over time. Here, we evaluated the intra- and inter-annual variations of several metals from 15 sites in the Matanza Riachuelo River basin (one of the most polluted in the world) and determined the physicochemical and meteorological parameters associated with these changes from 2008 to 2015. For this, in each site, we used Asymmetric Eigenvector Maps and Redundancy Analysis. The results highlighted temporal patterns of metal concentrations and several factors associated with them, perhaps related to the actions performed in the area since 2008. Additionally, we found that the effects of physicochemical and meteorological factors on metal concentrations were site-dependent, possibly related to the presence of different local sources of pollution or characteristics of the river in each site, such as its sediments. This approach could be applied to different scenarios (aquatic and terrestrial) and could provide a tool to help decision-makers address the harmful consequences of the continuous advance of human activities on human and ecosystem health.
Assuntos
Metais Pesados , Poluentes Químicos da Água , Humanos , Metais Pesados/análise , Ecossistema , Poluentes Químicos da Água/análise , Monitoramento Ambiental/métodos , Água/análise , Argentina , Rios , Sedimentos GeológicosRESUMO
We model the nocturnal patterns of the main vector of Leishmania braziliensis (Vianna) in the Paranaense region of South America, Nyssomyia whitmani (Antunes & Coutinho). Occurrence and abundance variation were analyzed by hourly periods, and in relation to sunrise and sunset to avoid differences in luminosity at fixed times throughout the year. The possible role of climatic and environmental variables on nocturnal activity curves was explored. A rotating light trap was operated biweekly in the peridomestic henhouse of a farm in Puerto Iguazú, from May 2016 to May 2018. Ny. whitmani, is the predominant Phlebotominae species (6,720 specimens captured), and is present throughout the night and seasons. Generalized additive models of nocturnal abundance of Ny. whitmani show a bell shape with an acrophase in the early evening. Models of abundance distribution as a function of total abundance showed significant nonlinear variations, only for the tertile of highest vector abundance, in the curves by hourly periods, and related to dawn, while female abundance relative to total abundance showed an asymptotic increasing curve, suggesting density-dependent events with abundance thresholds. Finally, temperature was the variable that best explained the pattern of abundance distribution of Ny. whitmani during the night, although triggers for scotophase activity due to internal clocks or luminosity could not be ruled out. The relationship of activity and abundance with climatic variables would also explain the nights of extraordinary abundance, and therefore of greater probability of vector-human and vector-reservoir contacts.
Assuntos
Leishmaniose Cutânea , Psychodidae , Humanos , Feminino , Animais , Argentina , Insetos Vetores , Estações do Ano , Brasil/epidemiologiaRESUMO
We study the geographical variation of the skull in the cavies Microcavia australis and M. maenas and its association with environmental variables. We tested four hypotheses previously proposed to explain the geographic patterns of morphological variation i) heat conservation; ii) heat dissipation; iii) primary productivity and iv) seasonality. We used 16 cranial measurements taken from 180 individuals. We analyzed the spatial variation in cranial morphology through Generalized Additive Models. Both species showed a north-south clinal gradient in skull size (increasing towards colder, less seasonal environments, with lower summer rainfalls in M. australis and towards warmer and seasonal environments in M. maenas). Microcavia australis presented greater ecomorphological variability than M. maenas, in agreement with its wider distribution and occurrence in more diverse environments. Also, the length of tympanic bullae in M. australis was larger towards its northern distributional range (associated to smaller skulls), and smaller to the south (associated to larger skulls). Overall, the distributional range of both species coincided with unproductive environments, where temperature represents a limiting factor and, together with rainfall, might determine the observed morphological patterns.
Assuntos
Roedores , Crânio , Animais , Geografia , Cobaias , Estações do AnoRESUMO
In aquatic systems, an interplay between bottom-up and top-down processes determines the dynamic of picocyanobacteria (Pcy) abundance and community structure. Here, we analyzed a 10-year time series (sampled fortnightly) from a hypereutrophic turbid shallow lake located within the Pampa Region of South America, generating the first long-term record of freshwater Pcy from the Southern Hemisphere. We used a cytometric approach to study Pcy community, and focused on its relations with nutrient and light conditions (bottom-up) and potential grazers (top-down). A novel Pcy abundance seasonality with winter maximums was observed for years with relatively stable hydrological levels, related with decreased abundance of seasonal rotifers during colder seasons. Pcy showed lower abundance and higher cytometric alpha diversity during summer, probably due to a strong predation exerted by rotifers. In turn, a direct effect of the non-seasonal small cladocerans Bosmina spp. decreased Pcy abundance and induced a shift from single-cell Pcy into aggregated forms. This structuring effect of Bosmina spp. was further confirmed by Pcy cytometric (dis)similarity analyses from the time series and in situ experimental data. Remarkably, Pcy showed acclimatization to underwater light variations, resembling the relevance of light in this turbid system.
Assuntos
Rotíferos , Zooplâncton , Animais , Lagos , Estações do Ano , América do SulRESUMO
Leishmaniases are a global health problem and in Argentina are considered emerging diseases. The new transmission scenarios of tegumentary leishmaniasis are especially important given that large areas of forest are being transformed into rural and urban systems. The aim of this study was to analyze the impact of the construction of a large public building and a neighborhood on the assemblage of Phlebotominae in a rural area with forest remnants and to correlate the changes observed in the species assemblage with characteristics of the environment. Entomological surveys with light traps were conducted on the construction campus in the northeastern region of Argentina at six sites representing different environmental situations. Structural environmental characteristics and meteorological conditions were recorded and analyzed. At least 16 species of Phlebotominae sand flies were collected, the most prevalent being Nyssomyia whitmani (Antunes & Coutinho), followed by the genus Brumptomyia (França & Parrot) and Migonemyia migonei (França). Our study provides evidence of how the structure of the assemblages and prevalent species respond to anthropogenic disturbances. As the construction progressed, both Ny. whitmani and the genus Brumptomyia were favored. The genus Brumptomyia was favored at sites surrounded by high proportions of forest, within patches of remnant vegetation, and relatively far from anthropogenic disturbances, while Ny. whitmani, the main vector of tegumentary leishmaniasis in the region, increases their abundant at short and intermediate distances from vegetation margins and areas close to anthropogenic disturbances, therefore increasing the risk of human exposure to vectors.
Assuntos
Biota , Psychodidae/fisiologia , Urbanização , Animais , Argentina , Feminino , Florestas , MasculinoRESUMO
We studied hantavirus seroprevalence and virus variability in rodent populations in Diego Gaynor, northwest of Buenos Aires province, Argentina. Rodent samplings were conducted in railroads and cropfield borders in March and July 1999, September and December 2000, and March 2001. Antibody detection was performed by an enzyme link immunosorbent assay (ELISA), using the recombinant nucleoprotein of Andes (AND) virus as antigen. Tissue samples were taken from positive antibody individuals in order to confirm the presence of hantavirus genomic material and to identify virus genotypes. Akodon azarae was the most abundant species, followed by Oligoryzomys flavescens, while Calomys laucha and C. musculinus were rarely caught. We found a rate of seroprevalence of 9.3% for a total sample of 291 A. azarae and 13.5% for 37 O. flavescens. After molecular analyses of hantavirus, we confirmed the presence of hantavirus genomic material in 16 individuals with ELISA (+) results and two individuals with ELISA (-). Four amplimers for each species were sequenced and compared to the corresponding sequences of representative hantaviruses. We identified the AND Cent Lec from three O. flavescens, and the Pergamino virus from four A. azarae and from one O. flavescens. A. azarae males had higher seroprevalence than females, and heavier individuals showed higher seroprevalence than lighter ones. We did not find seroprevalence differences according to sex in O. flavescens, although this result may have been produced by the low sample size. The lowest seroprevalence was found in a period of high rodent density, when juveniles prevailed in the population. We found higher seroprevalences than those detected in previous studies for other localities of central Argentina where cases of hantavirus pulmonary syndrome (HPS) have been reported. The presence of AND Cent Lec virus in rodent populations of the study area, which is responsible of HPS cases in central Argentina, suggests that human populations are at risk of HPS disease, although there were not reported cases of this disease until today.
Assuntos
Anticorpos Antivirais/sangue , Infecções por Hantavirus/veterinária , Orthohantavírus/imunologia , Doenças dos Roedores/epidemiologia , Animais , Antígenos Virais/imunologia , Argentina/epidemiologia , Reservatórios de Doenças , Feminino , Orthohantavírus/classificação , Infecções por Hantavirus/epidemiologia , Infecções por Hantavirus/virologia , Síndrome Pulmonar por Hantavirus/transmissão , Humanos , Masculino , Prevalência , Doenças dos Roedores/virologia , Roedores/classificação , Roedores/virologia , Estações do AnoRESUMO
We studied hantavirus seroprevalence and virus variability in rodent populations in Diego Gaynor, northwest of Buenos Aires province, Argentina. Rodent samplings were conducted in railroads and cropfield borders in March and July 1999, September and December 2000, and March 2001. Antibody detection was performed by an enzyme link immunosorbent assay (ELISA), using the recombinant nucleoprotein of Andes (AND) virus as antigen. Tissue samples were taken from positive antibody individuals in order to confirm the presence of hantavirus genomic material and to identify virus genotypes. Akodon azarae was the most abundant species, followed by Oligoryzomys flavescens, while Calomys laucha and C. musculinus were rarely caught. We found a rate of seroprevalence of 9.3 percent for a total sample of 291 A. azarae and 13.5 percent for 37 O. flavescens. After molecular analyses of hantavirus, we confirmed the presence of hantavirus genomic material in 16 individuals with ELISA (+) results and two individuals with ELISA (-). Four amplimers for each species were sequenced and compared to the corresponding sequences of representative hantaviruses. We identified the AND Cent Lec from three O. flavescens, and the Pergamino virus from four A. azarae and from one O. flavescens. A. azarae males had higher seroprevalence than females, and heavier individuals showed higher seroprevalence than lighter ones. We did not find seroprevalence differences according to sex in O. flavescens, although this result may have been produced by the low sample size. The lowest seroprevalence was found in a period of high rodent density, when juveniles prevailed in the population. We found higher seroprevalences than those detected in previous studies for other localities of central Argentina where cases of hantavirus pulmonary syndrome (HPS) have been reported. The presence of AND Cent Lec virus in rodent populations of the study area, which is responsible of HPS cases in central Argentina, suggests that human populations are at risk of HPS disease, although there were not reported cases of this disease until today