Reference values and drivers of diversity for South Brazilian grassland plant communities.

The South Brazilian grasslands (Campos Sulinos) form the dominant vegetation in southern Brazil. They are species-rich ecosystems that occur under distinct geomorphological and climatic conditions but spatial variation of plant species diversity remains understudied. Here, we present a detailed description of plant communities across the region. Our data were obtained in 1080 plots, representing well-preserved grasslands in different ecological systems. Apart from describing alpha and beta diversity, we investigated the relations of plant communities with environmental features. We identified 759 plant species and found clear differences in community composition across the region. Northern and Southern highland grasslands, humid and dry coastal grasslands and the mesic Pampa grassland were clearly distinct, related to climatic and edaphic features. While species abundance distribution was markedly uneven, local species richness was high, above 20 species/m2, especially in the highlands and in mesic Pampa sites, on shallow soils. The predominant component of beta diversity was species turnover, which suggests that a network of well-conserved grasslands distributed across the region would be the best strategy to protect plant diversity. Our results establish regionalized reference values for richness and diversity that can be useful for initiatives of restoration and conservation of these grasslands.

The Brazilian Cerrado is becoming hotter and drier.

The Brazilian Cerrado is a global biodiversity hotspot with notoriously high rates of native vegetation suppression and wildfires over the past three decades. As a result, climate change can already be detected at both local and regional scales. In this study, we used three different approaches based on independent datasets to investigate possible changes in the daytime and nighttime temperature and air humidity between the peak of the dry season and the beginning of the rainy season in the Brazilian Cerrado. Additionally, we evaluated the tendency of dew point depression, considering it as a proxy to assess impacts on biodiversity. Monthly increases of 2.2-4.0℃ in the maximum temperatures and 2.4-2.8℃ in the minimum temperatures between 1961 and 2019 were recorded, supported by all analyzed datasets which included direct observations, remote sensing, and modeling data. The warming raised the vapor pressure deficit, and although we recorded an upward trend in absolute humidity, relative humidity has reduced by ~15%. If these tendencies are maintained, gradual air warming will make nightly cooling insufficient to reach the dew point in the early hours of the night. Therefore, it will progressively reduce both the amount and duration of nocturnal dewfall, which is the main source of water for numerous plants and animal species of the Brazilian Cerrado during the dry season. Through several examples, we hypothesize that these climate changes can have a high impact on biodiversity and potentially cause ecosystems to collapse. We emphasize that the effects of temperature and humidity on Cerrado ecosystems cannot be neglected and should be further explored from a land use perspective.

Evaluation of effect of hazardous contaminants in areas for the abstraction of drinking water.

The lower portion of Taquari River is influenced by compounds from anthropic activities causing concern about the drinking water supplied to cities in the region. The study objective was to investigate the presence of contaminants at drinking water abstraction sites, defining the mutagenic effects of these stressors as an ecosystem quality parameter and its possible effects on human health. Geographic Information System techniques were used to investigate sources of contamination and it was found that agricultural activities predominated with a few medium and high potential pollutant agricultural activities, besides a soil area that was contaminated and undergoing an intervention process. Mutagenic effects were evaluated by Salmonella/microsome assay using TA98, TA97a, TA100, YG1041 and YG1042 strains in the presence and absence of metabolic activation (S9). Mutagenesis found in organic sediment extracts and surface water samples showed the prevalence of direct-acting mutagens at the drinking water abstraction sites. Taquari (Ta032, the sampling points were named according to the initial letters of the river (Ta), followed by the number of kilometers from the mouth) showed the highest mutagenic potency in sediment, while Ta063, at Bom Retiro do Sul, presented it in the water sample. In the Triunfo region (Ta011) there were significant responses in sediment and in water samples. The samples at General Câmara (Ta006) showed the least presence of contaminants. The Allium cepa test applied to sediments in natura showed significant micronucleus induction in Ta032 in accordance with the Salmonella/microssome assay. The test performed on Danio rerio embryos (FET) in the in natura water samples did not present significant responses. Chemical analyses of polycyclic aromatic hydrocarbons and metals already identified as chemical markers in the area indicated a small contribution to the mutagenic potency, calling attention to the fact that other direct-acting pollutants may be present at the drinking water abstraction sites.

Site Occupancy by Aedes aegypti in a Subtropical City is Most Sensitive to Control during Autumn and Winter Months.

The Aedes aegypti mosquito inhabits most tropical and subtropical regions of the globe, where it transmits arboviral diseases of substantial public health relevance, such as dengue fever. In subtropical regions, Ae. aegypti often presents an annual abundance cycle driven by weather conditions. Because different population states may show varying responses to control, we are interested in studying what time of the year is most appropriate for control. To do so, we developed two dynamic site-occupancy models based on more than 200 weeks of mosquito trapping data from nearly 900 sites in a subtropical Brazilian city. Our phenomenological, Markovian models, fitted to data in a Bayesian framework, accounted for failure to detect mosquitoes in two alternative ways and for temporal variation in dynamic rates of local extinction and colonization of new sites. Infestation varied from nearly full cover of the city area in late summer, to between 10% and 67% of sites occupied in winter depending on the model. Sensitivity analysis reveals that changes in dynamic rates should have the greatest impact on site occupancy during autumn and early winter months, when the mosquito population is declining. We discuss the implications of this finding to the timing of mosquito control.

Identification of foot and mouth disease risk areas using a multi-criteria analysis approach.

Foot and mouth disease (FMD) is a highly infectious disease that affects cloven-hoofed livestock and wildlife. FMD has been a problem for decades, which has led to various measures to control, eradicate and prevent FMD by National Veterinary Services worldwide. Currently, the identification of areas that are at risk of FMD virus incursion and spread is a priority for FMD target surveillance after FMD is eradicated from a given country or region. In our study, a knowledge-driven spatial model was built to identify risk areas for FMD occurrence and to evaluate FMD surveillance performance in Rio Grande do Sul state, Brazil. For this purpose, multi-criteria decision analysis was used as a tool to seek multiple and conflicting criteria to determine a preferred course of action. Thirteen South American experts analyzed 18 variables associated with FMD introduction and dissemination pathways in Rio Grande do Sul. As a result, FMD higher risk areas were identified at international borders and in the central region of the state. The final model was expressed as a raster surface. The predictive ability of the model assessed by comparing, for each cell of the raster surface, the computed model risk scores with a binary variable representing the presence or absence of an FMD outbreak in that cell during the period 1985 to 2015. Current FMD surveillance performance was assessed, and recommendations were made to improve surveillance activities in critical areas.

Traffic crashes and alcohol outlets in a Brazilian state capital.

OBJECTIVE: Restricting alcohol outlets is being considered as a measure for preventing alcohol-related crashes. However, in many developing countries, alcohol availability is not regulated and its influence on motor vehicle traffic crashes is unknown. This study explores the association between traffic crashes and alcohol outlets in a Brazilian city. METHOD: Data were geocoded and exploratory analysis was conducted using the kernel density estimator. Two generalized additive models (GAMs) were implemented to predict the factors associated with alcohol-related crashes. RESULTS: For 78 percent of the 3840 traffic crashes where the driver was a victim, there was at least one bar located within a 300-m radius. The median distances between an outlet were 124.4 and 130.7 m for a non-alcohol- and alcohol-related crashes, respectively (P =.13). The GAMs did not make evident any significant association between the outlet locations and alcohol-related crashes: the presence of at least one outlet was associated with alcohol-related crashes with an odds ratio (OR) of 0.94 (95% confidence interval [CI] = 0.75-1.17). Alcohol crashes are more likely to be observed among males (OR = 1.58; 95% CI = 1.21-2.06), young drivers vs. those aged 50 years+ (OR = 3.4; 95% CI = 1.79-6.43), and crashes with fatalities (OR = 1.73; 95% CI = 0.98-3.04). CONCLUSIONS: Density of alcohol outlets was high all over the city and both alcohol- and non-alcohol-related crashes occurred near an outlet. The study helps to better understand the relationship between alcohol availability and traffic crashes in a middle-income country where licensing/zoning is absent and suggests that measures for restricting the physical availability of alcohol are necessary, even though further studies are still needed.