Semiarid Region Of Northeastern Brazil Research Articles

Long-term effects of irrigated agriculture on Luvisol pedogenesis in semi-arid region, northeastern Brazil

Long-term irrigation in semi-arid regions leads to shifts in the soil moisture regime, affecting soil attributes and pedogenesis. Drylands are expected to increase worldwide, possibly because of climate change. Few studies have investigated changes in the pedogenic processes due to extensive irrigation in the Brazilian semi-arid region. This study assesses the effects of land use changes (irrigation and cultivation) on the morphological, physical, chemical, and mineralogical properties of soils. We evaluated two soil profiles in the semi-arid region in northeastern Brazil. We investigated an irrigated profile (IP) with long-term irrigation (26 years) and cultivation, and another profile under natural conditions (rain-fed hyperxerophilic Caatinga), that is, a non-irrigated profile (N-IP). The results indicate that land use affected chemical and mineralogical attributes of soils as well as the pedogenetic processes. Both soil profiles showed different behaviors in relation to salts: (1) reduction in soil exchangeable Na content (solodization) in IP, and (2) accumulation of soluble salts (salinization) and increased soil exchangeable Na content (solonization) in N-IP. Land use, possibly irrigation, induced mineralogical alteration pathways, such as the progressive mineral transformations via R0 MLM (mixed-layered minerals), suggesting differences in weathering and mineral evolution. The K-I (kaolinite-illite) and I-V (illite-vermiculite) phases predominated in the clay fraction in both soils and exhibited a greater trend for progressive kaolinization in IP. The other two MLMs (kaolinite-vermiculite, K-V and illite-smectite, I-S) were detected in N-IP and could be a proxy for the lowest weathering degree. This is consistent with the trend for a slight reduction in the SiO2/Al2O3 molecular ratio in IP. Illite was possibly the precursor mineral for other phyllosilicates, such as kaolinite, in IP. Fe-enriched MLM was detected in the decreasing sequence: illite, smectite, and kaolinite layers. The pedogenic trends observed, such as mineral weathering, may be attributed to system response to climate change.

Public policies on water resources for the brazilian northeastern semiarid region

ABSTRACT
 Objective: The present study has as main objective to identify the strategies taken by the municipal managers to adapt to the periods of greatest water difficulties in the northeastern semiarid, more specifically in the city of Doutor Severiano-RN, showing the importance of the development of these strategies in the region. Methodology / Approach: Research were made on the subject to identify which strategies were developed in the municipality, in addition, some field observations were made to identify the municipal public policies developed over the years. Conclusions: It is concluded with this study that it is essential to know the place and seek the best strategy to develop and apply these policies based on the characteristics of each region, considering the importance that they have for the social and economic development of the semiarid populations. Research limitations: The sample was extracted from works that addressed the topic in question, thus making the parallel of discourse between theory and practice. Originality / Value of the article: The study presents the strategies developed in the city of Doutor Severiano, to adapt to the periods of greatest water difficulties in the region, according to the climatic conditions of the place.

Anthelmintic resistance of gastrointestinal nematodes in sheep grazing in irrigated and dry areas in the semiarid region of northeastern Brazil.

This study aimed to determine the AR of gastrointestinal nematodes (GIN) to commercial drugs in sheep flocks naturally infected, grazing in irrigated (IA) and dry (DA) areas of the semiarid region in northeastern Brazil. Fecal egg count reduction tests (FECRT) were performed at 10 farms. From each flock, 36 adult sheep were selected and divided into five groups (G1 (0.08% ivermectin), G2 (10% albendazole), G3 (5% levamisole), G4 (1% moxidectin), G5 (10% closantel) and one control group, G6). All the commercial drugs were found to reduce the number of eggs per gram of feces (EPG). Resistance to ivermectin (37.1%), albendazole (52.1%), and levamisole (52.0%) was detected at all the farms, but nematodes proved to be susceptible to moxidectin (87.9%) and closantel (83.9%). The overall average efficacy of the commercial drugs was significantly higher (P < 0.05) in DA (49.2%), where moxidectin (90.4%) showed high effectiveness. The presence of the parasite Haemonchus contortus predominated at all the farms. The variables irrigated area (P = 0.002), intensive breeding (P = 0.018), uncovered enclosures (P = 0.05), cultivated (P = 0.043) and native/cultivated (P = 0.007) pastures, and rotational grazing (P = 0.013) were significantly associated with GIN infection; irrigated area (P = 0.009), semi-intensive breeding (P = 0.05), rotational grazing (P = 0.045), cultivated (P = 0.021) and native/cultivated (P = 0.04) pastures, and estimated weighing of animals (P = 0.002) were significantly associated with AR. Therefore, improved management practices and strategic deworming must be implemented to prevent the development of AR.

Cell damage, gas exchange, and growth of Annona squamosa L. under saline water irrigation and potassium fertilization

The semi-arid region of Northeastern Brazil has water limitations in terms of both quantity and quality, with salt stress as a limiting factor for increasing yield in most crops. In this context, the present study aimed to evaluate cell damage, gas exchange, and growth of custard apple under salt stress and potassium fertilization. The research was carried out at the Experimental Farm of CCTA/UFCG, in São Domingos-PB, Brazil. A randomized block design was arranged in a 2 × 5 factorial scheme, with two levels of electrical conductivity of irrigation water (ECw; 1.3 and 4.0 dS m-1) and five potassium doses (10, 15, 20, 25, and 30 g of K2O per plant per year). Water salinity of 4.0 dS m-1 negatively affected the stem diameter and number of leaves in custard apple at 179 and 210 days after transplanting (DAT). The highest relative growth in stem diameter in the period of 179-245 DAT was obtained in plants irrigated with 4.0 dS m-1 water and fertilized with 20 g of K2O per plant. Potassium doses of up to 30 g of K2O resulted in a higher percentage of cell damage and relative water content in custard apple leaf tissue. Water saturation deficit decreased with the increase in K2O doses in plants irrigated with water of 1.3 dS m-1. Irrigation with 1.3 dS m-1 water and estimated K2O doses ranging from 16 to 22 g per plant resulted in an increase in stomatal conductance, transpiration, CO2 assimilation rate, and instantaneous carboxylation efficiency in custard apple plants at 210 DAT.

Breaking the misconception of a dry and lifeless semiarid region: the diversity and distribution of aquatic flora in wetlands of the Brazilian Northeast

The semiarid region of northeastern Brazil possesses a set of wetlands characterized by hydrographic basins with deficient drainage networks, a few large and permanent lotic systems and several permanent and temporary lagoons. Aquatic plants are widely distributed in these wetlands and the present study aims to determine if those of Ceará state have similar species compositions and differences in species richness. We hypothesized that lentic ecosystems would have more species and different growth forms of aquatic angiosperms than lotic ecosystems. A total of 1619 records of aquatic angiosperms in 43 wetland areas were analysed. The most representative families were Cyperaceae, Poaceae, Fabaceae, Alismataceae, Malvaceae, Nymphaeaceae and Pontederiaceae. Most of the species are helophytes and bottom-rooted emergent hydrophytes. Permanent lentic ecosystems had the highest number of exclusive species (27.85 %), followed by temporary lentic ecosystems (20.54 %). Contrary to our hypothesis, the different aquatic ecosystems were found to possess distinct species compositions and different proportions of growth forms, and all wetland types contributed to the macrophyte richness of the study area, although they differ in species richness. Therefore, conservation plans for the native aquatic macrophyte biota should include all wetland ecosystems in the semiarid state of Ceará.

Comparison of the Reference Evapotranspiration among Empirical Methods and Penman-Monteith in Semiarid Region of Northeastern Brazil

The reference evapotranspiration (ETo) is a complex measure essential to water resources planning and management, irrigation scheduling and rational agricultural water use. This research aimed to evaluate the performance of the empirical methods in estimating reference evapotranspiration based on daily meteorological data of the surface and comparing them with the standard method of Penman-Monteith (PM-FAO 56), during the period of January/2004 to December/2013 for the climatic conditions of the semiarid region of Brazil. Five empirical methods were evaluated: Hargreaves-Samani (HS), Camargo (C), Thornthwaite (Th), Priestley-Taylor (PT) and Jensen-Haise (JH). For this purpose, maximum air temperature (Tmax, ºC) and minimum (Tmin, ºC); maximum air relative humidity (RHmax, %) and minimum (RHmin, %); maximum air atmospheric pressure (Pmax, kPa) and minimum (Pmin, kPa); average wind speed at a height of 2 meters (u2m, m s-1); global solar radiation (MJ m-2); and precipitation (mm) were used at this study. Analysis data were executed using descriptive statistics, correlation, dispersion, and statistical accuracy indexes to compare empirical models with the PM-FAO 56. The JH method overestimated the standard Penman-Monteith method, and underestimated by the HS, C, Th and PT methods, on a monthly average scale. In general, HS and JH methods had better adjustments with PM-FAO 56, on a daily scale. In conclusion, empirical methods, on a daily scale, presented good correlations and satisfactory statistical indices, being important in agricultural planning and irrigation management, becoming a good alternative for semiarid conditions of Petrolina-PE in San Francisco mesoregion. Comparação da Evapotranspiração de Referência entre Métodos Empíricos e Penman-Monteith em Região Semiárida do Nordeste Brasileiro R E S U M OA evapotranspiração de referência (ETo) é uma medida complexa essencial ao planejamento e manejo dos recursos hídricos, manejo de irrigação e uso racional da água na agricultura. O objetivo deste trabalho foi avaliar a precisão de métodos empíricos na estimativa da evapotranspiração de referência baseados em dados meteorológicos diários de superfície, comparando-os com o método padrão de Penman-Monteith da FAO-56 (PM-FAO 56), durante o período de janeiro/2004 a dezembro/2013, para as condições climáticas da região semiárida do Brasil. Foram avaliados cinco métodos empíricos: Hargreaves-Samani (HS), Camargo (C), Thornthwaite (Th), Priestley-Taylor (PT) e Jensen-Haise (JH). Para tanto, foram utilizados as seguintes variáveis: temperatura máxima do ar (Tmax, ºC) e mínima (Tmin, ºC); umidade relativa máxima do ar (RHmax, %) e mínima (RHmin, %); pressão atmosférica máxima do ar (Pmax, kPa) e mínima (Pmin, kPa); velocidade média do vento a uma altura de 2 metros (u2m, m s-1); radiação solar global (MJ m-2); e precipitação (mm). A análise dos dados foi realizada por meio da estatística descritiva, correlação, dispersão e índices estatísticos para comparar os modelos empíricos com o PM-FAO 56. O método de JH superestimou o método padrão de Penman-Monteith, enquanto que ocorreu a subestimativa pelos métodos de HS, C, Th e PT, na escala média mensal. Em geral, os métodos de HS e JH tiveram melhores ajustes com o PM-FAO 56, na escala diária. Em conclusão, os métodos empíricos, na escala diária, apresentaram boas correlações e índices estatísticos satisfatórios, sendo importantes no planejamento agrícola e manejo da irrigação, tornando-se uma boa alternativa para condições semiáridas de Petrolina-PE na Mesorregião do São Francisco.Palavras-chave: Vale do São Francisco, manejo da irrigação, seca, dados meteorológicos, recursos hídricos.

Abiotic factors driving cyanobacterial biomass and composition under perennial bloom conditions in tropical latitudes

While warming and eutrophication have increased the frequency and magnitude of harmful cyanobacterial blooms globally, the scenario for many eutrophic tropical freshwaters is a perennial year-round bloom. Yet, the drivers of persistent blooms are less understood when conditions such as light, temperature, and nutrients favor cyanobacteria growth year-round, and especially in regions facing recurrent periods of drought. In order to understand the drivers of cyanobacteria dominance, we assessed the abiotic conditions related to the abundance and dominance of the two dominant bloom-forming genera Raphidiopsis and Microcystis, in six shallow, man-made lakes located in the semiarid Northeastern region of Brazil during a prolonged regional drought. Lower water level corresponded to increased phosphorous and nitrogen concentration and, consequently, phytoplankton biomass. Cyanobacterial biomass was also proportional to phosphorus concentrations during year-round blooms. Yet, the two dominant cyanobacterial genera, Raphidiopsis and Microcystis, seldom co-occurred temporally and the switch between them was driven by water transparency. Our results illustrate the effects of drought induced water level reductions on the biomass and composition of cyanobacterial blooms in tropical shallow man-made lakes. Given the ideal year-round conditions (i.e., high light and temperature), droughts may be expected to intensify the risk and multitude of problems associated with eutrophication.

Population structure and fecundity of Macrobrachium jelskii (Miers, 1877) (Decapoda, Palaemonidae) on the Batateiras River, sub-basin of the Salgado River, in southern Ceará, Brazil

The freshwater prawn Macrobrachium jelskii (Miers, 1877) is a species with wide geographical distribution. However, the biological and ecological aspects of this species are poorly studied. Thus, the present study was carried out in Batateiras River, at the municipality of Juazeiro do Norte, located in the south of Ceará, in the semiarid region of northeastern Brazil. Samples were carried out monthly between January and December 2013, along the river margins. A total of 628 M. jelskii specimens were collected, 347 males and 281 females. The overall sex ratio was 1:0.81 (M:F). In relation to the carapace length, males reached sexual maturity at 5.1 mm while females reached morphological sexual maturity at 7.1 mm. Females were morphometrically larger than males, with means ​​of 7.04 mm (± 1.61) and 5.97 mm (± 0.78), respectively. The ovigerous females were more frequent in the rainy season. Female fecundity showed a positive correlation with growth. Thus, our results report previously unknown information about M. jelskii for a semiarid region of northeastern Brazil.

Bacteria Isolated from Free-range Chicken (Gallus gallus domesticus) Eggs Sold in Semiarid Conditions and its One Health Impact

Background: Food contamination is an important and growing public health concern due to the risk of foodborne illnesses. In this context, the egg, consumed all over the world, stands out. This food has been pointed out as a carrier of several bacteria, causing outbreaks of food toxinfection. The production of free-range chicken eggs (Gallus gallusdomesticus) has been an alternative for generating income for producers in Brazil; however, there is no monitoring of the sanitary quality of this product. The objective of this study was to identify microorganisms in 128 free-range chicken eggs sold in open markets in the semiarid region of Northeastern Brazil.Discussion: The frequency of bacterial isolation obtained in this study was high and reflects contamination of the eggs, which can occur through the shell, and factors such as air humidity, time and temperature favor the migration of bacteria from the shell to the internal content of egg. Food toxinfection occurs due to improper conditions in food processing, and it is essential to guarantee correct handling, promoting health quality. Therefore, some care related to egg management is necessary, from primary production to commercialization, ensuring food safety for consumers. Another point to be highlighted concerns the way of marketing this product. Eggs from free-range chickens are usually sold in open markets, kept at room temperature from production to final distribution, mainly in the semiarid region of Northeastern Brazil. Temperature, storage time and chicken’s characteristics (lineage, age, nutritional management and health status) are factors that have a direct influence on the quality of the food offered to the consumer. The high frequency of isolated bacteria warns of the implementation of control measures to avoid contamination of this product and the importance of the correct use of antimicrobials in poultry, in order to avoid the spread of resistance-carrying pathogens, minimizing economic, health and environmental impacts.

First occurrence of Backusella gigacellularis (Mucorales, Mucoromycota) in a fragment of an Upland Forest within the semi-arid region of northeastern Brazil

Abstract In a survey mucoralean fungi in the Brejo da Serra do Benedito, a fragment of Upland Forest in the semi-arid region of Pernambuco, Brazil, a specimen of Backusella gigacellularis was isolated. So far, B. gigacellularis (holotype) had only been isolated from soil in the Cerrado domain, in São Paulo state, southeastern Brazil. This is the second report of B. gigacellularis worldwide, and the first record to northeastern Brazil. A detailed description, as well as the illustration of the specimen, are presented.

Avaliação da evapotranspiração estimada pelo MODIS e do balanço hídrico para a bacia do Pontal-Pernambuco

A região semiárida do nordeste do Brasil tem forte tendência de diminuição da precipitação com as mudanças climáticas. Sabe-se que os impactos sociais, econômicos e ambientais serão muito altos se isso vier acontecer. A evapotranspiração e o balanço hídricos são variáveis importantes na tomada de decisão de políticas públicas relacionadas a chuva e recursos hídricos, uma vez que possibilita dar maior conhecimento do fornecimento de água em uma determinada região. Assim, avaliar diferentes metodologias de estimativas dessas variáveis proporciona uma importante contribuição para o planejamento de políticas públicas ambientais. Diante do exposto, este estudo tem o objetivo de avaliar a evapotranspiração estimada com MODIS e balanço hídrico obtido com o Soil Water Assessement Tools (SWAT) para a bacia do Pontal, Pernambuco, Brasil, para o ano de 2016. Os resultados mostram a grande dependência da evapotranspiração real e do escoamento superficial ao volume de chuva da bacia. Foi possível constatar, que as áreas de caatinga preservadas apresentaram as maiores evapotranspiração ao longo do ano. Destaca-se também o volume de água armazenado no solo nessas áreas. O maior volume escoado esteve presente na agropecuária e solo exposto. Esses resultados mostram os impactos das ações antrópicas sobre os recursos naturais da bacia do Pontal que podem acarretar maiores complicações na cobertura solo e balanço hídrico da região. Evaluation of evapotranspiration estimated by MODIS and water balance for the Pontal-Pernambuco basinA B S T R A C TThe semi-arid region of northeastern Brazil has a strong tendency to decrease precipitation with climate change. It is known that the social, economic, and environmental impacts will be very high if this happens. Evapotranspiration and water balance are important variables in public policy decision-making related to rain and water resources, as it allows for greater knowledge of the water supply in each region. Thus, evaluating different estimation methodologies for these variables provides an important contribution to the planning of environmental public policies. Given the above, this study aims to evaluate the evapotranspiration estimated with MODIS and the water balance obtained with the Soil Water Assessment Tools (SWAT) for the Pontal basin, Pernambuco, Brazil, for the year 2016. The results show the great dependence of actual evapotranspiration and runoff on the volume of rainfall in the basin. It was possible to verify that the preserved caatinga areas had the highest evapotranspiration throughout the year. Also noteworthy is the volume of water stored in the soil in these areas. The largest volume drained was present in agriculture and livestock and exposed soil. These results show the impacts of anthropic actions on the natural resources of the Pontal basin, which can lead to greater complications in the region's land cover and water balance.Keywords: Modeling, remote sensing, SWAT, MODIS.

Nitrogen fertilization on the agro-economic performance of sesame in the Brazilian semiarid

Abstract: The objective of this work was to evaluate the agro-economic performance of sesame (Sesamum indicum) under nitrogen fertigation in the semiarid region of Northeastern Brazil. The experimental design was randomized complete blocks with four replicates, and the treatments were arranged in a split-plot, where the plots were assigned five N rates (0, 30, 60, 90, and 120 kg ha-1) and the sub-plots were represented by four sesame genotypes ('CNPA G2', 'CNPA G3', 'CNPA G4', and 'BRS Seda'). The following variables were evaluated in two agricultural harvests in 2016: gross and net incomes, rate of return, and profit margin. In both harvests, there was a variation in production costs between N rates. In the second harvest, the highest values of net income were achieved with 120 kg ha-1 N fertigation, being: R$7,428.36 ha-1 for 'CNPA G2', R$8,630.74 ha-1 for 'CNPA G3', R$9,828.64 ha-1 for 'CNPA G4', and R$8,354.06 ha-1 for 'BRS Seda'. Increasing N rates provide an increase in the gross income, net income, rate of return, and profit margin for sesame producers. Fertigation with 120 kg ha-1 N provides the maximum agro-economic performance for sesame, whereas the 'CNPA G4' genotype shows the greatest agro-economic efficiency.

The potential of “umbuzeiro” genotypes for the development of preserves

ABSTRACT: One of the relevant economic importances of the “umbuzeiro” (Spondias tuberosa Arruda) to the northeastern semiarid region of Brazil is the fruit processing to obtaining preserves. However, there are limitations in the production and standardization of this product, such as color, taste and texture, which are problems in the quality, identity, making it harder to achieve new markets. This study was carried out aiming to evaluate the potential of “umbu” genotypes (Access 37, Access 44, BRS 48, BRS 52, BRS 55 and BRS 68) registered by Embrapa in the development of preserves. It was evaluated the product pH, total acidity, water activity, soluble solids, moisture, firmness, color (L*, a*, b*), reducing and non-reducing sugars, vitamin C, syneresis and consumer acceptance regarding the overall impression. The CATA method was applied to describe the sensorial profile of the samples. According to the results, it was observed a significant difference (p≤0.05) in the physico-chemical composition of the samples, being samples produced from the access 37 and BRS 68 more appropriated for processing of preserves (in bars), with greater firmness and less syneresis. Consumers indicated products from the genotypes 37, 44, BRS 52 and BRS 55 as the ones with highest acceptance regarding the overall impression; the consumers associated the samples in different characterizations, associating the access 37 and BRS 68 with the characteristics of firm and delicious; the commercial sample was characterized as acid, adstringent and terrible.

Leguminosas arbóreas com potencial fertilizante: uma abordagem multivariada

The objective of this study was to evaluate, through multivariate data analysis, which tree legume residues have the best fertilizer potential for agricultural crops in the semi-arid region of northeastern Brazil. The experiment was conducted in pots, in a randomized block design, with seven treatments and four replicates. Treatments consisted of residues of Sabiá, Jurema Preta and Gliricidia, besides two parts of the plant: leaves and leaves + branches. The pots were filled with 8.0 dm3 of soil and the residues were added in the form of green mass, corresponding to 73.0 g of dry mass per pot. Maize seeds were sown and, at 65 days after addition of the residues, soil chemical attributes, growth and nutrient contents in the plants were evaluated. The data were studied through principal component analysis, clustering analysis, canonical discriminant function analysis and means comparison test from canonical variable 1. Gliricidia residues positively influenced soil K and Mg contents, as well as height, stem diameter, number of leaves and leaf contents of P, N and Mg in maize plants. These residues showed greater dissimilarity and separation compared to the control treatment and led to statistically higher means compared to the other treatments. Jurema Preta leaves positively influenced soil Ca, N and TOC, as well as leaf contents of K and Ca and total dry mass of maize. Multivariate statistical analysis made it possible to identify distinct potentials among legume residues for use as fertilizer in maize crop, and Gliricidia is the species with highest potential.

Systemic coccidioidomycosis in a dog in Northeastern Brazil

ABSTRACT: We described a case of systemic infection by Coccidioides sp. in a dog. An adult, mixed breed, free-ranging male dog presented with clinical signs that included apathy, cachexia, anorexia, limited mobility with sternal recumbency, bilateral mucopurulent ocular discharge, dyspnoea, pulmonary crepitation, erosive and nodular lesions on the skin, and swelling and stiffness of the left tibiotarsal joint. The dog was submitted to a postmortem examination. Grossly, there were multiple yellow to white nodules in various organs. Histologically, the lesions were characterized as pyogranulomatous inflammation associated with fungal spherules morphologically consistent with Coccidioides sp. The dog was concomitantly diagnosed with undifferentiated sarcoma affecting the skin, lymph nodes, liver, and testicles. The diagnosis of coccidioidomycosis was made based on the histologic changes associated with morphotintorial features and positive immunolabeling of organisms with anti-Coccidioides immunohistochemistry. This case demonstrated that Coccidioides sp. can infect dogs that inhabit urban centers in the semiarid region of Northeastern Brazil, likely due to exposure to dust from contaminated environments.

Food Security and coexistence with the semiarid zone in areas affected by drought in the backlands of Pernambuco

ABSTRACT Objective Between 2010 and 2017, it was registered one of the most intense droughts in the Brazilian Northeastern Semiarid region, when the rainfall was below the historical level for the region. This context was related to water scarcity for human consumption and productive activities in this territory, where the semiarid backlands of the state of Pernambuco are located. The objective of this study was to assess the condition of food security and its associated factors in areas affected by drought in the semiarid zone of Pernambuco, Brazil. Methods It was a cross-sectional study on a populational base. Data were collected by socioeconomic and demographic surveys, and the Brazilian Food Insecurity Scale, which were applied to 252 households, from September to October 2015. The data was analyzed by socioeconomic and demographic characterization of the households, and the identification of the food insecurity prevalence and its associated factors, by Poisson regression. Results The prevalence of food insecurity was high (74.6%). Among those, 9,1% were on starvation, which means severe insecurity. Food insecurity was statistically associated to sanitation, per capita income, and the number of household residents. Lack of money was the main self-reported cause to food insecurity. Conclusion The high prevalence of food insecurity being associated to indicators of great social vulnerability shows the role of social and economic inequities on the inadequate access to food amongst families in the semiarid zone on a nearly generalized low-income context. These findings corroborate to the evident need of expanding and reinforcing public policies, as well sustainable development models to prioritize and promote social inclusion of communities at greater vulnerabilities in the Brazilian semiarid area. Thus, the need of these economic and social public strategies is highlighted by the worsening of historical vulnerable conditions due to the cycles of droughts on this region.

The risk of oral transmission in an area of a Chagas disease outbreak in the Brazilian northeast evaluated through entomological, socioeconomic and schooling indicators

Chagas disease is a neglected tropical disease strongly associated with low socioeconomic status, affecting nearly 8 million people – mainly Latin Americans. The current infection risk is based on acute case reports, most of which are typically associated with oral transmissions. In the semi-arid region of Northeastern Brazil, serious outbreaks of this transmission type have surged in the last years. One of those occurred in 2016 in the state of Rio Grande do Norte. Rural residents of four municipalities surrounding Marcelino Vieira ingested sugar cane juice – which was probably ground with Trypanosoma cruzi-infected insects. Eighteen cases of Chagas disease were confirmed serologically, with two deaths reported. Socioeconomic information, schooling of residents and the structure of peridomestic and domestic environments in the rural area of Marcelino Vieira, along with entomological indicators, were investigated to understand better the factors related to the outbreaks in this region. We found triatomines (mainly Triatoma brasiliensis) in 35% (24/67) of domiciliary units and all rocky outcrops inspected (n = 7). Overall, 25% (91/357) of examined T. brasiliensis were infected by T. cruzi in artificial ecotopes, with almost the same prevalence in the sylvatic environment (22%; 35/154). Among all ecotopes investigated, wood/tile/brick piles were the ones linked to high insect infestations and triatomine T. cruzi infection prevalence. Ninety-five percent of people interviewed recognized the triatomines and knew the classic route of transmission of disease – triatomine bite-dependent. However, only 7.5% admitted knowledge that Chagas disease can also be acquired orally – which poses a risk this transmission route currently recognized. Here, we highlight the physical proximity between humans and triatomine populations with high T. cruzi infection prevalence as an additional risk factor to oral/vector contaminations. In sum, residents have low income, low level of education, and/or a willful disregard for the routes of Chagas disease transmission (specifically oral transmission), a combination of factors that may have favored the Chagas disease outbreak. We here provide recommendations to avoid further outbreaks.

Transposition of the São Francisco River and socio-demographic vulnerability: challenges to the well-being of the countryside population

O principal objetivo deste trabalho consiste em verificar como a mobilidade populacional decorrente da obra da transposição do rio São Francisco pode intensificar a vulnerabilidade sociodemográfica dos espaços urbanos da Área de Influência Direta (AID) desse empreendimento. O Projeto de Transposição localiza-se no semiárido setentrional do Nordeste brasileiro, espaço marcado pelas frequentes secas e pela desigualdade social e econômica. Originalmente destinado a mitigar os efeitos da seca, o Projeto de Transposição, em parte, traz consigo impactos não somente ambientais, mas principalmente sociais e demográficos. Nesse contexto, a mobilidade populacional é uma das questões demográficas decorrentes do Projeto de Transposição, por ser uma componente capaz de mudar rapidamente o tamanho e a composição da população nas áreas impactadas, que traz preocupações sobre as questões sociais (pobreza e exclusão social). No Brasil, pouco se tem abordado sobre a dimensão dos deslocamentos populacionais em torno da temática dos megaprojetos, ainda mais considerando os aspectos da vulnerabilidade sociodemográfica. Com base em informações do Censo Demográfico de 2010 e no arcabouço teórico de literaturas nacionais e internacionais que versam sobre a temática, buscou-se criar um índice sintético de vulnerabilidade sociodemográfica para analisar os impactos da mobilidade populacional decorrente do Projeto de Transposição. Os principais resultados mostram que o Projeto de Transposição agrava, em certa medida, os desafios a serem enfrentados pela população dos lugares mais próximos aos canais da obra, haja vista a fragilidade de capital humano (saúde, educação) e físico (habitação, deslocamento) dos migrantes residentes na AID.

Effects of model calibration on hydrological and water resources management simulations under climate change in a semi-arid watershed

Semi-arid regions are known for erratic precipitation patterns with significant effects on the hydrological cycle and water resources availability. High temporal and spatial variation in precipitation causes large variability in runoff over short durations. Due to low soil water storage capacity, base flow is often missing and rivers fall dry for long periods. Because of its climatic characteristics, the semi-arid north-eastern region of Brazil is prone to droughts. To counter these, reservoirs were built to ensure water supply during dry months. This paper describes problems and solutions when calibrating and validating the eco-hydrological model SWIM for semi-arid regions on the example of the Pajeú watershed in north-eastern Brazil. The model was calibrated to river discharge data before the year 1983, with no or little effects of water management, applying a simple and an enhanced approach. Uncertainties result mainly from the meteorological data and observed river discharges. After model calibration water management was included in the simulations. Observed and simulated reservoir volumes and river discharges are compared. The calibrated and validated models were used to simulate the impacts of climate change on hydrological processes and water resources management using data of two representative concentration pathways (RCP) and five earth system models (ESM). The differences in changes in natural and managed mean discharges are negligible (< 5%) under RCP8.5 but notable (> 5%) under RCP2.6 for the ESM ensemble mean. In semi-arid catchments, the enhanced approach should be preferred, because in addition to discharge, a second variable, here evapotranspiration, is considered for model validation.

Gas exchange, growth, and production of mini-watermelon under saline water irrigation and phosphate fertilization

In the semi-arid region of Northeastern Brazil, due to the occurrence of excess salts, both in the water and soil, plants are constantly exposed to various conditions of abiotic stress. Thus, it is extremely important to identify methods capable of minimizing the effects of salt stress on plants as a way to ensure the expansion of irrigated areas. In this context, the objective of this study was to evaluate the gas exchange, growth, and production of mini-watermelon irrigated with saline waters and fertilized with phosphorus. The experiment was conducted in pots under greenhouse conditions in Pombal, PB, Brazil, using a randomized block design in a 5 x 4 factorial scheme, corresponding to five levels of electrical conductivity of irrigation water—ECw (0.3, 1.3, 2.3, 3.3, and 4.3 dS m-1), four phosphorus doses— PD (60, 80, 100, and 120% of the recommendation), and with three replicates. Watermelon plants cv. Sugar Baby were sensitive to water salinity greater than 0.3 dS m-1, with more pronounced inhibition of gas exchange, growth, and production. Reduction in the CO2 assimilation rate of watermelon plants cv. Sugar Baby was associated with factors of stomatal and non-stomatal origin. Phosphorous doses corresponding to 73 and 88% of the recommended values promoted an increase in the intercellular CO2 concentration and stem diameter of mini-watermelon plants. P2O5 doses ranging from 60 to 120% of the recommendation did not mitigate the effects of salt stress on the cultivation of watermelon cv. Sugar Baby.