Semiarid Region Of Northeastern Brazil Research Articles

Irrigation Depth and Carnauba (Copernicia prunifera) Straw Increase Water Use Efficiency in the Cherry Tomato in a Semi-Arid Region

This research addresses irrigation strategies for saving water, including the use of irrigation depths of 50, 75, 100, 125 and 150% of the crop evapotranspiration (ETc) and a ground cover of carnauba straw, in evaluating the response of the cherry tomato (Solanum lycopersicum var cerasiforme L) submitted to different levels of water availability in soil with and without ground cover, in the semi-arid region of northeastern Brazil. The physiological components showed higher values under ground cover and when submitted to 100% ETc. The greatest number of total and commercial fruit was obtained when the soil was covered, and irrigated with depths of 75 and 100%. Carnauba straw with irrigation depths of 100 and 125% resulted in the greatest fresh fruit weight. The highest values for fruit diameter and length were achieved in the soil under cover. Maximum productivity, 11,404.20 kg ha-1, was obtained at 107.5%, while for the soil with no ground cover, maximum productivity was 7,778.86 kg ha-1, obtained with an irrigation depth of 140%. Based on the results, soil productivity is possible without a cover of carnauba straw, at an irrigation depth of 50.5%, which can generate savings of 3400 m³ water-cycle-1 ha-1. In addition, water use efficiency in the cherry tomato was 3.06 kg m-3 and 1.95 kg m-3, with and without ground cover respectively. It can be concluded that the use of carnauba straw makes it possible to reduce water consumption in the 'red' cherry tomato under conditions of water scarcity.

Identification of sorghum hybrids for silage production in the semiarid (BSh) region of northeastern Brazil

The objective of this study was to identify the hybrids of sorghum most suitable for the production of silage in the semiarid regions of northeastern Brazil. Twenty-three hybrids were evaluated in a randomized block design with three replicates. The dry mass yield; dry mass of leaf, stem, panicle, grains, and senescent matter; and chemical composition of the plant were evaluated. The pH, ammoniacal nitrogen (N-NH3), and chemical composition of the silage were also assessed. The hybrids 947252, FEPAGRO 18, 12F042226, and SF 11 performed best in terms of morphological characteristics, with the highest mass of leaves and grains. The hybrid FEPAGRO 19 had the highest dry matter value (443.3 ± 17.0 g kg-1), whereas the hybrid 12F042496 had the lowest value (271.3 ± 17.0 g kg-1). The dry matter (DM) content of the other hybrids was within the recommended values for silage production (280 to 400 g kg-1). High levels of crude protein were observed in the grouped hybrids 12F042496, 947254, and 12F042422. The hybrid 12F042496 had the highest neutral detergent fiber content. The hybrids 9929036, 9929030, 9929012, 947254, 947072, PROG 134 IPA, 12F042226, 12F042422, and BRS 506 had pH values ranging between 3.8 and 4.2, indicating good quality silage. Overall, the sorghum hybrids 9929030, 12F042224, 12F042150, FEPAGRO19, and FEPAGRO11 had the best growth and production characteristics, and plant and silage chemical composition, and are thus recommended for the production of silage in the semiarid of northeastern Brazil.

Respostas da qualidade da água e fitoplânctons à redução de vazão e recepção de cargas de sedimentos no reservatório de Xingó/AL

In the semi-arid region of northeastern Brazil, the Xingo reservoir is the last of a series of cascading reservoirs in the Sao Francisco river basin. From the perspective of river flow, the sharp reduction of rainfall in 2012 promoted the program of average flow reduction from 2013, contextualized by the most severe reduction in flow over the last hundred years. In 2015 a bottom discharge was given to the Delmiro Gouveia reservoir for the Xingo reservoir, raising concern about the effects of these actions on the water quality of this reservoir. Given the complexity of water quality variations in aquatic ecosystems, it is necessary to expand the panorama of physical and chemical responses of reservoir waters inserted in cascade systems. This article aims to evaluate the effects of average flow reduction, in the period from 2010 to 2015 of the Sao Francisco River basin, and of bottom discharge on the quality of Xingo reservoir water, also used for human supply. For this purpose, secondary data on rainfall, flow and water quality were collected by CHESF at three monitoring points on the Lake, representative of the anterior, intermediate and posterior parts. The results showed that the event of flow reduction allied to upstream sediment discharge led to an increase in temperature and alteration in nutrient concentration with consequent proliferation of cyanobacteria.

Constrictotermes cyphergaster (Blattaria, Termitidae) termite nests as substrates for lichen fixation in the semiarid region of northeastern Brazil.

Constrictotermes cyphergaster (Blattaria, Termitidae) termite nests as substrates for lichen fixation in the semiarid region of northeastern Brazil.

Physically based model for gully simulation: application to the Brazilian semiarid region

Abstract. Gullies lead to land degradation and desertification as well as increasing environmental and societal threats, especially in arid and semiarid regions. Despite this fact, there is a lack of related research initiatives. In an effort to better understand soil loss in these systems, we studied small permanent gullies, which are a recurrent problem in the Brazilian northeastern semiarid region. The increase in sediment connectivity and the reduction of soil moisture, among other deleterious consequences, endanger this desertification-prone region and reduce its capacity to support life and economic activities. Thus, we propose a model to simulate gully-erosion dynamics, which is derived from the existing physically based models of Foster and Lane (1983) and Sidorchuk (1999). The models were adapted so as to simulate long-term erosion. A threshold area shows the scale dependency of gully-erosion internal processes (bed scouring and wall erosion). To validate the model, we used three gullies that were over 6 decades old in an agricultural basin in the Brazilian state of Ceará. The geometry of the channels was assessed using an unmanned aerial vehicle and the structure from motion technique. Laboratory analyses were performed to obtain soil properties. Local and regional rainfall data were gauged to obtain sub-daily rainfall intensities. The threshold value (cross-section area of 2 m2) characterizes when erosion in the walls, due to loss of stability, becomes more significant than sediment detachment in the wet perimeter. The 30 min intensity can be used when no complete hydrographs from rainfall are available. Our model could satisfactorily simulate the gully-channel cross-section area growth over time, yielding a Nash–Sutcliffe efficiency of 0.85 and an R2 value of 0.94.

Veredas da Chapada do Araripe: subespaços de exceção no semiárido do estado do Ceará, Brasil

Na região do Cariri cearense, as singularidades naturais, sobretudo nas áreas de influência direta da Chapada do Araripe, reafirmam seu caráter de exceção dentro do semiárido do Nordeste brasileiro e definem as Veredas como subespaços de exceção. Neste artigo, busca-se apresentar as particularidades naturais das Veredas da Chapada do Araripe, que são possuidoras de Gleissolos Melânicos Tb distróficos, ácidos, muito intemperizados, com predomínio de cargas negativas. Esses solos sustentam renques de buritis, entre outras freatófitas, que são heranças de uma complexa evolução paleoclimática e paleoecológica, mantidos atualmente pelas influências das zonas de exsudação. As Veredas da Chapada do Araripe são classificadas do ponto de vista geomorfológico, pertencentes a 4 (quatro) tipos específicos: de Patamar, de Depressão em Chapadão de Sopé e de Encosta, formam-se nessas posições topográficas em função da profundidade do lençol freático, tendo seu processo evolutivo relacionado com o sistema de erosão e recuo de escarpa. As Veredas da Chapada do Araripe, encontram-se atualmente refugiadas e tensionadas pelo clima semiárido.
 Palavras-chave: Chapada do Araripe; Espaço de exceção; Veredas; Cariri cearense.

Fast recovery of house infestation with Triatoma brasiliensis after residual insecticide spraying in a semiarid region of Northeastern Brazil.

The northeastern semiarid region stands out in the Brazilian context regarding the eco-epidemiology of Chagas disease, in which Triatoma brasiliensis is the main vector of Trypanosoma cruzi. Persistent house invasion threatens the relative levels of progress achieved over previous decades. We conducted an intervention trial with a five-year follow-up to assess the impacts of residual spraying with pyrethroid insecticides on house infestation with T. brasiliensis in 18 rural villages (242 houses) located in the Tauá, Ceará. House infestations were assessed by systematic manual searches for triatomines in every domestic and peridomestic habitat on five occasions. Triatomines were collected in peridomestic (57.5%), sylvatic (35.8%), and intradomiciliary (6.7%) habitats. The most important ecotopes of T. brasiliensis were containing roofing tiles, bricks or rocks (23.4% ± 9.1). Residual insecticide spraying substantially reduced baseline house infestation rates from 27.9% to 5.9% by 6 months post first spraying (MPS). The decline was substantially greater in intradomiciles (11.2% to 0.8%) than in peridomiciles (16.7% to 5%). The mean relative density of triatomines recovered its preintervention values at 14 MPS in intradomiciles, and in the main peridomestic ecotopes. The house infestation levels recorded at 14 MPS persisted thereafter despite all reinfested houses were selectively sprayed on every occasion. Overall average bug infection rates with T. cruzi in the five occasions were in intradomiciles (11.1%), peridomiciles (4.7%) and wild habitats (3.3%). In peridomicile T. cruzi infection rates decreased significantly at all stages after chemical intervention. In intradomicile, the only significant difference occurred at 20 MPS (7.7% to 30.8%). The vectorial capacity of T. brasiliensis, combined with its invasive potential from sylvatic sources and the limited effectiveness of chemical control in the harsh caatinga landscape, pose serious obstacles to the definite elimination of domestic transmission risks. Systematic vector surveillance supported by community participation and locally adapted environmental management measures are needed to reduce the risks of establishment of domestic transmission with T. cruzi in this region.

Phytomass and quality of yellow passion fruit seedlings under salt stress and silicon fertilization

The semiarid region of Northeastern Brazil is characterized by long drought periods, and the use of saline waters appears as an alternative for the expansion of irrigated areas. Associated with the use of these waters, silicon fertilization constitutes an important attenuator of salt stress. In this perspective, this study aimed to evaluate the phytomass production and quality of the passion fruit cultivar ‘Gigante Amarelo’ grown with saline water and silicon fertilization. The experiment was conducted in a plant nursery belonging to the Center of Agrifood Science and Technology, in the municipality of Pombal-PB. A completely randomized block design in a 5 x 5 factorial scheme was used, referring to five levels of electrical conductivity of the irrigation water (0.3, 1.0, 1.7, 2.4, and 3.1 dS m-1) and five doses of silicon fertilization (0; 25; 50; 75, and 100 g of potassium silicate/plant), with four replications and two plants per plot. The phytomass accumulation (leaves, stem, and roots), as well as the total dry phytomass, shoot dry phytomass, root/shoot ratio, and the quality index of Dickson were evaluated. The data obtained were subjected to the F-test at 0.01 and 0.05 level of probability. The electrical conductivity of water from 0.3 dS m-1 caused the decrease of phytomass production in seedlings of the passion fruit cultivar ‘Gigante Amarelo’, although it is possible to produce good quality passion fruit seedlings with water salinity up to 3.1 dS m-1. The doses of silicon fertilization mitigated the effect of salt stress on the root/shoot ratio of plants of the passion fruit cultivar ‘Gigante Amarelo’.

Application strategies of saline water and nitrogen doses in mini watermelon cultivation

Salt stress is highlighted as one of the limiting factors for the establishment of agriculture in the semiarid region of Northeastern Brazil. In this context, it is essential to look for new strategies aiming at minimizing the effects of salt stress on the crops. The present work aimed to evaluate the photochemical efficiency, photosynthetic pigments, and growth of the watermelon cv. Sugar Baby under different use strategies with saline waters and nitrogen fertilization. The experiment was conducted in a protected environment at the Center of Technology and Natural Resources of the Federal University of Campina Grande, municipality of Campina Grande, Paraíba. An experimental design in randomized blocks was adopted, arranged in a 6 x 2 factorial scheme, with six management strategies of water salinity and two nitrogen doses (corresponding to 50 and 100% of the recommendation), with five replications. Two salinity levels of the irrigation water were studied, one with low and another with a high level of electrical conductivity of the water (ECw = 0.8 and 3.2 dS m-1). The watermelon cv. Sugar Baby expressed higher sensitivity to salt stress in the flowering phase, with a decrease in the synthesis of chlorophyll b, chlorophyll total, and carotenoids. The 50% dose of N provided an increment in the initial fluorescence, stem diameter, and the number of leaves of the watermelon cv. Sugar Baby. The length of the main branch of the watermelon plants decreased with the salt stress applied in the fructification phase; however, the fertilization with 100% of N stimulated a higher growth when the irrigation with saline waters was performed at the vegetative and flowering phases.

Quality and management status of the drinking water supplies in a semiarid region of Northeastern Brazil

Surface and groundwater resources in the Seridó Region (Brazilian semiarid) were investigated to evaluate their current quality conditions and suitability for domestic use. The water was characterized in terms of physical, chemical, and radiological parameters; including those required by the Brazilian Drinking Water Quality Standard (DWQS). Information about major and trace elements and radiological aspects of the water are reported for the first time. Salinization was confirmed as a key problem in the region, driven natural and anthropogenic. Overall, water has poor organoleptic characteristics. The concentration of most trace elements was below the recommended level, except for uranium and selenium in groundwater. Gross alpha and beta activities higher than the recommended levels were also recorded in several water samples, mostly from the investigated aquifers. In these samples, a detailed radionuclide analysis is required to estimate the effective dose received by the local population. Overall, the results show that water from the investigated region is not suitable for human consumption unless proper treatment is applied. Water requires proper treatment to decrease the content of dissolved salts, toxic elements, and radionuclides responsible for the high gross alpha and beta activities.

Effect of biochar application on production parameters of two cowpea cultivars planted in succession in five soils from the Brazilian semiarid region

In a context of the need to improve agricultural production combined with sustainable soil management practices, the present work aimed to assess the effect of increasing doses of biochar on production parameters of two cowpea cultivars planted in succession on five soils from the Brazilian northeastern semiarid region. Soils assessed were Typic Haplustepts, Typic Haplustults, Typic Hapludox, Typic Ustifluvents, and Typic Ustipsamments. Biochar was produced with wood from pruning cashew trees. Biochar doses were 0.0, 3.5, 7.0, and 10.5 t ha−1. Two cowpea cultivars were planted in succession, BRS Potengi in the first cycle and BRS Guariba in the second. The following production variables were assessed: number of grains per pod, average pod length, hundred-grain weight, and grain yield. Experimental data from each cycle were submitted to analysis of variance using the F-test. The effect of biochar doses was assessed by regression analysis. The cowpea production parameters in the first cycle showed an increasing response as biochar dose increased for the five soils. A positive linear response of production variables in the second cycle indicated the residual effect of applying biochar in the soils Haplustults, Ustifluvents, and Haplustepts, which presented the highest response of most variables to biochar in both cycles. The results obtained without fertilization indicate the benefits of using biochar as amendment in soils of the Brazilian semiarid region, at least up to a dose of 10.5 t ha−1.

COMPARATIVE ANALYSIS OF THE IMPACT OF LIBRAS ON DEVELOPMENT OF THE DEAF: A CASE STUDY IN A CITY IN NORTHEASTERN BRAZIL

Currently, 9.7 million people in Brazil have some hearing impairment, who use a sign-visual language to communicate, the Brazilian Sign Language (LIBRAS). The discussion about education in an inclusive perspective of the deaf and Brazilian Sign Language has been expanded in recent years by education professionals, as well as by the deaf community itself. In this context, the present study sought to analyze the impact of the Brazilian Sign Language on the development of the deaf in the city of Acopiara-CE, located in the semiarid region of northeastern Brazil, through a case study structured in a descriptive and exploratory research. Data collection was carried out in three stages: visiting the deaf and his family, to explain the study, applying an identification questionnaire and applying a fundamental level I test. Thus, it was possible to analyze the reality of two deaf subjects , residents of the same city, approximate age range, who had their school journey diverging from each other, in which the mastery of the Brazilian Sign Language allowed a greater evolution in the inclusive process of one of the individuals. In conclusion, it was observed that inclusive education is still a subject of discussion, but proficiency in LIBRAS is fundamental to the inclusive process of the deaf.

ESPACIALIZAÇÃO DAS CHUVAS EM UMA BACIA HIDROGRÁFICA NO SEMIÁRIDO DA PARAÍBA

O semiárido nordestino do Brasil apresenta altas temperaturas associadas a baixos valores pluviométricos, que ocorrem de forma intensa e mal distribuída no espaço geográfico. Nessa perspectiva, existe a necessidade de compreensão da dinâmica das chuvas no perímetro seco no intuito de fundamentar as diversas formas de gestão dos recursos hídricos. No entanto, a disponibilidade de dados pluviométricos nessa região por vezes é escassa, o que implica a interpolação como meio de compreensão da distribuição ou espacialização das chuvas em diversos recortes espaciais. As análises quantitativas dos dados de chuva permitem compreender a dinâmica e relação com os principais sistemas de precipitação de determinada área de estudo. Sendo assim, o objetivo deste trabalho é quantificar e espacializar os dados de chuva correlacionando-os com os sistemas produtores de chuva entre um ano mais chuvoso e outro seco da bacia de drenagem do Alto Curso do Rio Piranhas, Semiárido (PB) entre janeiro de 1996 e dezembro de 2016. Dado o exposto, foi possível identificar que o ano de 2008 foi o mais chuvoso e 2012 o mais seco da série, e que a atuação da ZCIT varia interanualmente nos respectivos anos de acordo com a temperatura da TSM.

Use of Duddingtonia flagrans in the control of gastrointestinal nematodes of feedlot goats

This study aimed to evaluate the use of a sodium alginate matrix-pelletized formulation of Duddingtonia flagrans for biological control of gastrointestinal nematodiasis in feedlot goats in the semiarid region of Northeastern Brazil. We used 20 Saanen female goats (age, 4 months; average weight, 12 kg) that did not receive anthelmintic treatment and had counting of eggs per gram of faeces (EPGs) ? 500. The animals were divided into two groups: in group 1 (D. flagrans group), each animal received 3 g of pellets (0.6 g of D. flagrans mycelium) per 10 kg of body weight, twice a week, over 4 months; and in group 2 (control group), each animal received 3 g of pellets without fungus per 10 kg of body weight, twice a week, over 4 months. Each group was maintained in a separate 15-m2 stall. Larval cultures and measurements of weight, EPG, and packed cell volume (PCV) were performed every 15 days. We observed low EPG levels in the D. flagrans group throughout the experimental period, with a significant difference (p < 0.05) on day 30 and from day 60, having, at the end of the experiment, average OPG values of only 150, reduction of 92.3% when compared to control group. Haemonchus sp. was the most prevalent helminth in all larval cultures. The D. flagrans group showed a mean weight gain of 8.8 kg at the end of the experiment (p < 0.05), while the control group showed a mean weight gain of 4.8 kg. The best PCV results (p < 0.05) were also observed in the D. flagrans group from day 30. Thus, the use of D. flagrans pellets in a sodium alginate matrix was effective in controlling gastrointestinal nematodiasis of feedlot goats in the semiarid region of Northeastern Brazil.

Adjustments in the tetrazolium test methodology for assessing the physiological quality of Jatropha mollissima (Euphorbiaceae)

Jatropha mollissima is a species of the semiarid region of northeastern Brazil. It is known that individuals of the same species may present differences in seeds viability, thus it is necessary to define methodologies to evaluate the physiological potential of seeds. This study aimed at determining the best pre-moistening time and the concentration of the tetrazolium solution to evaluate the viability of J. mollissima seeds. Three pre-moistening times were tested (12, 14 and 16 hours) and two tetrazolium solution concentrations (0.25 and 0.5 %). As a comparative study, a germination test was performed, which consisted of two treatments: seeds between paper and on vermiculite. The values obtained in the tetrazolium test were similar, with average viable seeds of 21.3% for concentration 0.25 % and 27.3 % for the concentration of 0.5 %. It was observed, in the germination test, that the percentage of germination had averages equal to 22.5 % for the treatment between paper and 13.5 % for the treatment with vermiculite. The best procedure for performing the tetrazolium test in J. mollissima seeds is using the concentration of 0.25 % of tetrazolium solution, pre-moistening time of 16 hours, between paper at 25 oC and staining for 4 hours at 40 °C in the dark.

Phytochemical Screening and Betaxanthines of Pilosocereus catingicola (Gürke) Byles & Rowley Subsp. salvadorensis (Werderm.) Zappi (Cactaceae)

In the semiarid region of northeastern Brazil, we find several cacti that are very important for the regional fauna and flora, including the “facheiro” (Pilosocereus catingicola (Gürke) Byles & Rowley subsp. salvadorensis (Werderm.) Zappi, a species that belongs to this botanical family and is widespread in the Paraiba semiarid region. The objective of this study was quantify and characterize the chemical constituents of the fruits and cladodes of Pilosocereus catingicola subsp. salvadorensis. The fruits were lyophilized and the samples were subsequently ground. A 2 gram aliquot of the lyophilized material was solubilized in 5 mL of 50% MeOH and 50 mmol L-1 of sodium ascorbate and distilled water. The extractive content was monitored by absorbance in a UV-VIS Meter® SP2000 (600 nm) spectrophotometer. Analyzes were performed using the SAS® Program (North Carolina, USA), version 9.2. The constituent groups identified on the stem were the phenolic and tannin groups: steroids, tannins, flavonoids, and saponins. Betalains are the group of alkaloids of greater expression in the fruits of this species, from which the betaxanthines are its main constituents, such as vulgaxanthin III, muscarine and dopaxanthin. Pilosocereus catingicola is a potential source of these metabolites in different parts of the plant, which, therefore, justifies encouraging the best employment of the species.

ESTIMATES OF GENETIC PARAMETERS FOR SELECTION OF COLORED COTTON FIBER1

ABSTRACT Naturally-colored cotton fiber has received attention from breeding programs in the semiarid region of northeastern Brazil due to an increased interest in its fibers. Therefore, this study aimed to select genotypes of colored cotton fiber for agronomic and technological fiber characteristics for the Brazilian semi-arid conditions. The experiment was carried out in two environments (Patos-PB and Apodi-RN) in Brazil during the 2016 growing season. The experimental design was in randomized blocks with four replications. Treatments consisted of eleven colored fiber genotypes and three controls (BRS Topázio, BRS Rubi, and BRS Verde). The following traits were assessed: seed cotton yield (SCY, kg ha-1), lint percentage (LP, %), lint length (LEN, mm), lint strength (STR, gf tex-1), and lint micronaire (MIC, µg in-1). The data were submitted to individual and joint variance analyses, and means were grouped by the Scott and Knott (1974) test at 0.05 probability. Genotypes showed variability in all traits, which allows genetic gains in subsequent cycles of selection. The genotypes BRS Topázio, CNPA 2002 10245, and CNPA 2002 10327 presented the best estimates for the assessed traits, thus they can be selected for future studies in cotton breeding programs in the semiarid region.

PHYSICOCHEMICAL QUALITY OF FRUITS OF WEST INDIAN CHERRY UNDER SALINE WATER IRRIGATION AND PHOSPHATE FERTILIZATION1

ABSTRACT In the semiarid region of Northeastern Brazil due to the qualitative and quantitative scarcity of water resources, the use of saline water should be considered as an alternative to expand irrigated agriculture. However, the use of waters with high levels of salts depends on management practices that minimize deleterious effects on plants. In this context, the objective of this study was to evaluate the effects of irrigation with water of increasing salinity and fertilization with phosphorus on the postharvest physicochemical composition of fresh fruits of West Indian cherry, cv. ‘BRS 366 Jaburu’. The research was carried out in a protected environment, in lysimeters with Neossolo Regolítico Psamitico Típico (Entisol) of clay loam texture, using a randomized block design, in a 5x2 factorial scheme with three replicates and one plant per plot, relative to five levels of irrigation water electrical conductivity (0.6; 1.4; 2.2; 3.0 and 3.8 dS m-1) and two phosphorus doses [100 and 140% of the recommendation of Musser. Increase in water salinity reduced fruit size and fresh mass formation, but increased soluble solids contents and titratable acidity in the pulp of West Indian cherry fruits. Phosphate fertilization, regardless of dose, stimulated the formation of fresh mass of West Indian cherry fruits. Water salinity inhibited the formation of ascorbic acid in West Indian cherry fruits, and the highest value was observed in plants irrigated with 0.6 dS m-1 water and fertilized with a dose of 100% of the recommendation of P2O5.

High frequency of seropositive and carriers of Leptospira spp. in pigs in the semiarid region of northeastern Brazil.

Carrier animals are considered key in the transmission cycle of leptospirosis. Although investigations have been carried out on several species, the role of pigs in the epidemiology of the disease is still poorly studied in the semi-arid region. Thus, the objective of this study was to determine the presence of Leptospira spp. in the genitourinary tract of pigs intended for slaughter. Fifty pigs were used: adults and unvaccinated. Samples of the kidney, urine, and vaginal fluid were collected for the molecular detection of Leptospira spp. and blood samples for the serological test. The molecular test was performed using the polymerase chain reaction (PCR), and the serological test was performed with the microscopic agglutination test (MAT). Samples with DNA amplification were submitted to genetic sequencing. Twenty (40%) animals were found with anti-Leptospira spp. antibodies, and the majority of the reactions (50%) occurred for the serogroup Tarassovi. Leptospiral DNA was found in the tissue of 11 (22%) pigs. The gene from a urine sample was sequenced and showed similarity to L. borgpetersenii. The results evidenced a high rate of porcine carriers; therefore, they appear to be important sources of agent infection, being potential transmitters of the disease to other animal species and man.

Phytoplankton scenario and microcystin in water during extreme drought in semiarid tropical water supplies, Northeastern Brazil.

The objective of this study was to characterize the limnological, microystin and phytoplankton community of five tropical eutrophic reservoirs located in the Brazilian northeastern semi-arid region, used for domestic use at the time of extreme drought and reduction of water volume. The study was conducted in July and August 2015, and an integrated sample of the water column was collected at three points near the dam in each reservoir. Analysis of limnological parameters, identification and quantification of phytoplankton, with emphasis on cyanobacteria were performed, as well as detection of microcystin by means of immunoassay (ELISA). The reservoirs presented ~ 90% water volume reduction. High turbidity and concentrations of nitrogen and phosphorus, as well as high cyanobacterial densities, revealed an increase in the eutrophic state for hypereutrophy. The total biovolume of phytoplankton and cyanobacterial density is high, plus an average increase in relation to previous studies of 350% and 150%, respectively. The density of cyanobacteria and microcystin concentration presented values ​​above acceptable levels for drinking water according to Brazilian legislation. A phytoplankton community was represented by 17 functional groups, including potentially toxic cyanobacteria species such as Planktothrix agardhii (S1), Microcystis aeruginosa (M), Anabaena planktonica e Anabaena spp. (H1), Cylindrospermopsis raciborskii (Sn). Our results confirm that conditions of extreme drought and reduction of the volume of the reservoirs influence the composition, biovolume of phytoplankton and water quality, but not the increase of total microcystin in the analysed, although above 1μg-1 registered a significant decrease of water quality in used for human consumption.