Francisco River Research Articles

Heavy metal contamination in a highly consumed Brazilian fish: immunohistochemical and histopathological assessments.

Due to industrial, rural, and domestic waste disposal, heavy metals such as cadmium (Cd), chromium (Cr), lead (Pb), zinc (Zn), copper (Cu), and iron (Fe) continually infiltrate aquatic environments. These pollutants do not degrade naturally and, thus, have a high capacity for bioaccumulation in tissues and organs. The present study uses histological and immunohistochemical analyses to evaluate the contamination status of Salminus franciscanus, a large and economically important fish. Levels of Cd, Cr, Pb, Zn, Cu, and Fe were evaluated by atomic absorption spectrometry in the liver and muscle of fish sampled from two tributaries of the upper São Francisco River Basin, Brazil: the Abaeté and Paraopeba Rivers. In addition, histopathological alterations and expressions of three environmental biomarkers were assessed: metallothionein (MT), heat shock protein-70 (HSP70), and cytochrome P450-1A (CYP1A). The results show that fish from the Paraopeba River are unsuitable for human consumption, with several metals being detected above the safe limits established by the World Health Organization. Histopathological alterations in the liver and spleen were also significantly more frequent in fish from the Paraopeba River than in those from the Abaeté River (P < 0.05). Significant differences in the expressions of environmental biomarkers were observed between the rivers. Fish from the Abaeté River presented significantly higher values of the gonadosomatic index (GSI) and lower levels of metal contamination in the liver and muscle.

Caracterização química do solo em uma área de recuperação de um depósito de metalurgia de zinco

Ore processing generates a large amount of sterile and waste from purification and concentration processes. This material, in contact with the environment, can cause major environmental impacts. CMM-Votorantim at Três Marias benefits silicate and sulphide Zn ores. The tailings from one stage of the process are deposited in an area called PH9 on the banks of the São Francisco River and subsequently removed and placed in a waterproofed settling basin. The area of the old deposit presented problems in the process of environmental recovery and, therefore, it became opportune to investigate chemically the level of contamination there. The area has 14.4 ha and is located in the municipality of Três Marias / MG with a slope towards the bed of the São Francisco River. The soil samples were collected in two cross profiles, one North - South and the other East - West, totaling 29 georeferenced points with a distance of 20 m. A soil sample was collected at each point. After preparation at the Soil Laboratory of Unimontes, Campus Janaúba - MG, the samples were analyzed in the ICP OES laboratory of the NGqA of the CPMTC of UFMG - Campus Belo Horizonte. Total and available concentrations of calcium, magnesium, aluminum, iron, manganese, copper, zinc and organic matter, together with pH were determined. For the graphical representation, we opted for a grouping the results in pH ranges versus concentrations. The results show that the area has magnesium contamination, thus causing severe structural degradation of the soil. The concentrations of the other elements in the PH9 area are within the limits allowed for land use in agricultural activity, but approaching the upper limit allowed.

The relative role of glacial refugia and longstanding barriers in the diversification of a fossorial squamate

The Neotropics host the highest number of species of the biological realms, but the roles of Pleistocene climatic oscillations and longstanding geographic barriers on the origins of this remarkable biodiversity remains debated. Here, we test the relative contribution of these evolutionary mechanisms on the genetic and phenotypic diversification of Amphisbaena pretrei, a poorly studied amphisbaenid from eastern Brazil. Ecological niche modelling identified a large area along the coast of north-eastern Brazil that remained climatically stable since the last glacial maximum (21 kyr). Morphological analysis revealed the existence of differentiation in the southernmost sampled locality, despite generalized morphometric conservatism. Genetic structure was organized into two clades that are separated by the São Francisco river and that diverged some 3 Myr, before the recent Pleistocene glacial cycles. Coalescent analyses rejected all scenarios that included demographic changes, supporting instead diversification under population stability, also confirmed by neutrality tests. Taken together, our results support a prominent role of the São Francisco river as a longstanding barrier favouring the diversification of the fossorial A. pretrei, relative to recent Pleistocenic demographic dynamics. Generally, this study shows that including species with diverse natural histories is necessary before attempting any generalization regarding the evolutionary processes underlying Neotropical biodiversity.

Temporal streamflow reduction and impact on the salt dynamics of the São Francisco River Estuary and adjacent coastal zone (NE/Brazil)

During the past decades, the São Francisco River basin encountered substantial changes due to intensive human activities such as river regularization and damming, and more recently, climate change. As a result, a decrease of streamflow in the lower São Francisco River sector has received considerable attention due to its drastic geomorphological and hydrodynamic changes. This study presents a detailed investigation on the changes of streamflow and its effect on spatiotemporal migration of estuarine plume along the São Francisco coastal zone from 1994 to 2017 based on salinity and water temperature extracted from HYCOM numerical modeling.The progressive saltwater intrusion from in situ observation for 2005 and 2017, is analyzed. The results show two distinct periods with substantial inter-annual variability of streamflow during the period from 1994 to 2011 and accentuated decreasing trends from the second semester of 2012 onwards, and discontinuous periodicities from later 2012 due to the extreme hydrological events of droughts. The spatiotemporal variability in salinity and water temperature on the coastal zone revealed a severe retraction of the estuarine plume due to the low streamflow rates, which started after the second semester of 2012, and the presence of Tropical Surface Waters (TSW, S > 35.9 g/kg) closer to the river mouth, shifting the previous estuarine mixing zone from the coastal region to inward areas of the estuary. The continuous penetration of saltwater towards inner areas of the São Francisco estuary (∼10 km upstream from estuary mouth) is attributed to the decline of water flow supply from the river upper reaches due to the extreme drought events and water conservation measures. These changes may lead to potential ecological and human problems due to persistent high salinity above the limit for human consumption (S > 0.5 g/kg) from the estuary mouth to the limits of local cities along the river.

Analysis of groundwater and river stage fluctuations and their relationship with water use and climate variation effects on Alto Grande watershed, Northeastern Brazil

Sustainable use of water resources on the behavior of groundwater table and surface water level variations, especially in phreatic sedimentary aquifers, where a strong interaction between stream flow and groundwater normally takes place. In the present study, precipitation, water level fluctuation, river flow and pivot installation data from an important agricultural frontier with an increasing water use for irrigated agriculture and a downward precipitation trend were compared with surface and water level fluctuation monitoring data. The main purpose was to assess possible impacts on the aquifers and to analyze the variation in groundwater table and surface water levels due to long-term downward precipitation trend (climate variation effects) and increasing water demand (irrigation). A growing number of central pivots installed for irrigation are withdrawing water from the Urucuia Aquifer System (UAS) in western Bahia State, Northeastern Brazil, one of the leading agricultural frontiers of the world. Field surveys provided hydrogeological aspects that led to the construction of a hydrogeological conceptual model. Monitoring groundwater and surface water through Brazilian Geological Survey's Integrated Groundwater Monitoring Network (RIMAS-CPRM), satellite images and Hydrological Information System (HidroWeb-ANA) network formed the databases for the study. This data was compared with rainfall data and evolution of irrigated areas captured by satellite image analysis. Results indicate that reduction of rainfall volumes from 1990 to 2018 in the headwaters of Alto Grande basin, due to cyclic droughts, and an increase in surface and groundwater exploitation due to flourishing agribusiness activity has caused a considerable groundwater level drawdown. The drawdown of up to 6.63 m points to the need of strong management actions, which should provide a long-term sustainable use of water resources (superficial and underground) within Alto Grande watershed. This study is part of the actions undertaken to provide the scientific and technical basis to secure the availability of water and a sustainable agricultural activity, since an important part of the Cerrado, the Brazilian savanna ecosystem, and considerable proportion of São Francisco river flow, lies in the study area.

Fish diversity in three tributaries of the São Francisco river, Brazil

We evaluated fish diversity in three tributaries of the São Francisco River, one of the largest watercourses in Brazil. The study site is in the sub-basin of the Carinhanha River [Carinhanha, Cocos (I and II) and Itaguari Rivers], located in the South region of the Bahia state. These rivers are crossed by bridges of the federal highway BR-135. After sampling, upstream and downstream from each bridge, during drought and rain seasons, 3,520 specimens of fish (57 species, 21 families) were captured. The species with highest occurrence were Astyanax cf. taeniatus, Serrapinnus heterodon, Astyanax bimaculatus and Astyanax cf. rivularis. During drought season, the number of specimens captured was higher, leading to an increase of species dominance. In the rainy season, species diversity was higher with a greater distribution of individuals among species. The data indicate the maintenance of the fish faunal structure despite anthropogenic activities on the studied areas.

In vitro response of date palm (Phoenix dactylifera L.) inflorescence explants to high 2iP and 2,4-D concentrations

One of the major problems related to the implementation of date palm crops in Brazil is propagation. Therefore, the aim of this study was to evaluate the possibility of using tissue culture technique for the in vitro propagation of this species. Hence, the effect of 2iP and 2,4-D on the in vitro response of date palm inflorescence tissues, related to floral bud swelling, callusing, and rhizogenesis, was evaluated. The absence of 2,4-D was more detrimental to the in vitro response of inflorescence bud explants than absence of 2iP. In treatments without addition of 2,4-D to the culture medium, explants did not have swelling, callus or root formation. The treatment containing 150 mg/L 2,4-D in the presence of 1.5 mg/L 2iP initiated explant swelling, and treatments with either 100 mg/L or 150 mg/L 2,4-D, combined with 3.0 mg/L 2iP, were also efficient in stimulating in vitro swelling of inflorescence buds. Rhizogenesis was induced at the highest concentrations of 2,4-D (100 and 150 mg/L), combined with 4.5 mg/L 2iP, and was visually more evident in the treatment containing 150 mg/L 2,4-D + 4.5 mg/L 2iP. These results suggest that even higher concentrations of these two reagents might be efficient in the micropropagation of new existing date palm genotypes in the Submedium São Francisco River Valley.

Sporolithon franciscanum sp. nov. (Sporolithales, Rhodophyta), a New Rhodolith-Forming Species from Northeast Brazil

This paper describes Sporolithon franciscanum, a new rhodolith-forming species of non-geniculate coralline algae found at depths between 47–52 m near the São Francisco river mouth, the second largest and the most extensive drainage basin in Brazil, and also at the Abrolhos Bank, in the world´s largest rhodolith beds. DNA sequences from plastidial psbA and rbcL markers indicate that the species is unique compared to all other Sporolithon species that have thus far been sequenced. Since morpho-anatomical features of the new species are shared with some other Sporolithon species, its identification was only confirmed by DNA sequences.

Song variation in the Caatinga suboscine Silvery-cheeked Antshrike (Sakesphorus cristatus) suggests latitude and São Francisco River as drivers of geographic variation

Historical processes may result in patterns of differentiation among extant populations, which may lead to diversification and speciation. This is often expressed, and measured, as genetic and behavioral variation among populations. Suboscine birds acquire songs by innate mechanisms and are typically poorly studied relative to oscine birds, which may learn songs and thus develop unique dialects among populations. Behavioral features, including song, are extensively used to describe the structure and geographical variation in bird populations. In turn, this knowledge may shed light onto patterns of species diversification across ecoregions, which is particularly relevant in endemic species. Here we investigate for the first time song structure and variation in the Silvery-cheeked Antshrike, an endemic bird of a poorly studied South American dry forest, the Caatinga. We evaluate hypotheses for song diversification, correlating vocal acoustic parameters with geographic patterns and environmental variables. We measured temporal and spectral variables in the song of Sakesphorus cristatus across 14 localities spanning almost the entire range of the species’ distribution. The song presents a clear geographic pattern, and vocal variation was congruent with a barrier by the Sao Francisco River superimposed to a latitudinal clinal variation that was uncorrelated to climate variables. We argue that these regional differences may have a genetic basis since S. cristatus is a suboscine antbird that should not show song learning (social adaptation) and, apparently, does not have the song correlated to habitat features (acoustic adaptation). More detailed studies are required to test further hypotheses about the drivers of this potential genetic variation underlying the geographical variation in this suboscine bird song.

A diagnostic framework to assess the governance of the São Francisco River Basin Committee, Brazil

AbstractEnvironmental governance requires integrating social‐institutional governance and river basin management as part of the sustainable river basin development. This remains challenging and few tools exist to facilitate this objective. As part of a diagnostic governance framework on basin management in the São Francisco River Basin in Brazil, this paper investigates the influence of four governance indicators of institutions, leadership, collaboration, and learning. Data on governance and biophysical condition were collected through semi‐structured stakeholder interviews and indicator scoring. Institutions were found to be robust and based on shared values, despite adherence to different paradigms (top‐down vs. bottom‐up) and lack of transparency and clarity of roles. It was found that leadership, and its function of decision making, required enhanced subsidiarity and autonomy for the river basin committee. Collaboration was based on mutual respect, but needed to be improved to achieve fairer water allocation and payments, social justice, and ecological sustainability. It was found that learning requires better knowledge transfer and capacity building at municipal level. The current São Francisco Basin Plan (2016–2025) will build on a robust history of capacity building, but should include governance indicators for performance evaluation of environmental governance.

Drought impacts, social organization, and public policies in northeastern Brazil: a case study of the upper Paraíba River basin

The upper Paraíba River basin plays a key role in controlling the flow from the Epitácio Pessoa Reservoir, a major reservoir in the semiarid region of Paraíba state. The objective of this study is to analyze historical droughts and public policies and their impacts on the social organization in the upper Paraíba River basin, which is located in the semiarid region of Brazil. In this study, the following methodological procedures were used: (a) historical survey of drought occurrence and dam construction in the semiarid region of Brazil, (b) data processing of hydrologic records (rainfall and streamflow), and (c) field visits to collect and compare data on the changes in the volume of water stored behind dams. The results showed that state intervention in the semiarid region follows a trend based on the characteristics of each historical moment and the interests of the groups that comprise the state sector. It is also observed that the implementation of several public policies, such as social programs, construction of dams, and the transfer of water from the São Francisco River, has resulted in significant changes in the streamflow behavior in this semiarid region. These changes have differed in magnitude depending on the hydrological characteristics of each period (i.e., dry, rainy, or normal). Finally, the use of dams for water management in the semiarid region was identified as the main factor influencing water security and social organization.

Water demand prospects for irrigation in the São Francisco River: Brazilian public policy

Abstract This study analyzed how irrigation expansion in the São Francisco Hydrographic Region (SFRH) could affect water availability in four physiographic regions: Upper, Middle, sub-Middle, and Lower SFRH. The Brazilian National Water Resources Plan (PNRH) is the main policy for water resources in Brazil. The PNRH, however, did not evaluate how the expansion of the irrigated area could affect water demand. We use a detailed computable general equilibrium model (CGE), applicable to Brazil, to simulate expansion scenarios in irrigated areas for 2025 and 2035, according to the Water Resources Plan for the São Francisco River (SFP). Simulations were carried out for areas deemed potentially suitable for irrigation. The Climatic Water Balance (CWB) was estimated for the SFRH to compare water supply and water demand. Results suggest that cities located in the Upper and Middle São Francisco Regions would present greater irrigation potential due to water availability and proximity to large irrigated areas. The comparative result of the CWB and the CGE model shows water availability problems in the states of Alagoas and Pernambuco, in particular, cities located in the São Francisco Lower Region.

High gene flow in two migratory Neotropical fish species, Salminus franciscanus and Brycon orthotaenia, and implications for conservation aquaculture

Abstract Two migratory and endangered freshwater fish species, Salminus franciscanus and Brycon orthotaenia, are endemic to one of the most important basins for hydropower capacity in South America. These two fish are target species of conservation aquaculture programmes along the São Francisco River system. In order to implement effective strategies for the conservation of these species, microsatellite markers were developed and used to assess the genetic diversity and structure among wild groups. Fish were collected during the spawning season at four sampling sites, covering more than 1000 km. Polymorphism loci were assessed, and a total of 133 and 107 alleles were found for S. franciscanus and B. orthotaenia, respectively. Despite the critical conservation status, B. orthotaenia showed high levels of genetic diversity, comparable with those of other closely related species. Salminus franciscanus exhibited half of the genetic diversity of its sister species in terms of allelic diversity, indicating that this species will be more prone to genetic drift and inbreeding in conservation aquaculture programmes. The results of an analysis of molecular variance for microsatellite markers in these species (FST = 0.007 for S. franciscanus and FST = 0.003 for B. orthotaenia) and the estimated recent migration rates (&gt;40% among sampling sites) support panmixia in both species, despite the heterogeneities of the riverscape. The results of this study and the microsatellites developed will play an important role in assisting agencies in making informed decisions on conservation aquaculture programmes.

A new carbon nanomaterial solid-phase microextraction to pre-concentrate and extract pesticides in environmental water

This research describes a solid-phase microextraction device using carbon nanomaterials supported on steel threads. The device was used to pre-concentrate and extract 24 pesticides in water. The carbon nanomaterials were obtained by a chemical vapor deposition (CVD) process, using methane and acetonitrile as carbon source. The different pesticides were separated, detected, and quantified using gas chromatography coupled to mass spectrometry (GC-MS). The system, optimized and validated in the laboratory, presented good results. Linearity was between 0.0007 and 50.00 μg L−1, with determination coefficients greater than 0.9. The detection and quantification limits were in the range of 0.0002–1.1309 μg L−1 and 0.0007–3.7320 μg L−1, respectively. The studied pesticides presented recovery values in the range of 70 ± 8 to 123 ± 18%. Carbon nanomaterials exhibited high thermal and mechanical resistance, as the same fiber could be used for approximately 300 extractions. The device was applied to analyze environmental water samples collected from the São Francisco river basin in Brazil and in the Chinampas in Mexico City.

Occurrence and abundance of clinically relevant antimicrobial resistance genes in environmental samples after the Brumadinho dam disaster, Brazil

On January 25th 2019, the structure damming a pond containing ore mining wastes and iron burst at Brumadinho City, Brazil. About 11.7 million m3 of a tailings-mud mixture was released from the dam, causing destruction along 300 km of the Paraopeba River toward the São Francisco River. The environments with a high content of metals may provide a suitable environment for horizontal gene transfer, including antimicrobial resistance genes (ARGs). Therefore, this study aimed to detect and quantify clinically relevant ARGs in environmental samples after the Brumadinho dam disaster. Soil, sediment, and water samples were collected within 300 km of the Brumadinho dam disaster at unaffected and affected sites. Physical-chemical parameters of water samples were measured. Total DNA was extracted and 65 clinically relevant ARGs were researched by PCR. The most prevalent ARGs were selected for real-time quantitative PCR analysis. The average of the physical-chemical parameters was higher in the affected sites when compared to the unaffected sites, especially turbidity, concentration of Fe and Al. A total of 387 amplicons from 29 ARGs were detected, which confer resistance to β-lactams, quinolones, aminoglycosides, tetracyclines, sulphonamides, phenicols, macrolides, glycopeptides, and polymyxins, including extended-spectrum β-lactamases-encoding genes, and mcr-7.1. The sul1 gene had higher total concentrations than blaTEM, tetB and qnrB in the environmental samples, and the diversity and abundance of ARGs increased at the sites affected by the Brumadinho dam disaster. Therefore, we point out that the contamination by the Brumadinho dam disaster tailings resulted in an increase in the amount and abundance of ARGs in the environment.

Channel curvature effects on estuarine circulation in a highly stratified tropical estuary: The São Francisco river estuary (Brazil)

The effects of the channel curvature on estuarine circulation were assessed in the São Francisco river estuary. This estuary is a deltaic front system, with a highly stratified salinity distribution. The assessment was based on field experiments where currents and salinity and temperature were monitored during a semi-diurnal tidal cycle in two cross-sections with distinct curvatures (radii of 2 and 8 km). The least-squares method was used to determine the mean velocity (residual velocity), and the tidal velocity amplitude and phase for the M2 harmonic. The results for the M2 harmonic were compared to an analytical solution that considers a simplified momentum balance between barotropic pressure gradient and bottom friction. The model skill for these two results was 0.44 and 0.63 for sections #A and #B, respectively. The differences between these results indicate that there are other dynamically influential forces for the longitudinal momentum balance besides those included in the analytical solution. The baroclinic pressure gradient presented values two orders of magnitude greater than the bottom friction, demonstrating the dynamic importance of this force. Although centrifugal acceleration is a component of the lateral momentum balance, it also plays a role in the distribution of longitudinal currents in the cross-section, displacing the maximum currents towards the exit of the curve. In addition to the channel curvature effect, the influence of the bathymetry was also observed on the tidal amplitude in the cross-sections and on the depth-averaged residual longitudinal velocities along the sections, with the highest average speed in the shallowest areas of each section.

Cowpea response to different irrigation depths in the Submedium São Francisco River Valley, in Juazeiro, BA, Brazil

Different cowpea genotypes respond differently to water regimes and to different climatic conditions. The aim of this study was to evaluate the response of cowpea to different irrigation depths in the Submedium São Francisco River Valley, Brazil. The experiment was conducted at the experimental field of DTCS/UNEB, in Juazeiro, BA, Brazil, from November/2016 to January/2017, in a 2 x 5 factorial scheme randomized block design (cowpea genotypes x irrigation depths), with three replicates. The genotypes used were BRS Acauã and Canapu and irrigation depths, obtained based on 50, 75, 100, 125, and 150% of ETo. Physiological characteristics, production components and water use efficiency were analyzed. Increased irrigation depths only caused a significant effect on mass of one 100 grains. With water availability and climatic conditions observed during the experiment, BRS Acauã outperformed Canapu, with a better yield performance. BRS Acauã genotype had a better response in water use efficiency for grain yield, exceeding Canapu by 47.21%.

PALYNOLOGICAL ORIGIN, PHENOLIC CONTENT AND ANTIOXIDANT PROPERTIES OF GEOPROPOLIS COLLECTED BY MANDAÇAIA (MELIPONA MANDACAIA) STINGLESS

ABSTRACT The stingless bee Melipona mandacaia (Smith 1863) (mandaçaia) is found only in the region of Caatinga, Northeastern Brazil, in the states of Bahia and Pernambuco, near to São Francisco river. The aim of the present work was to determine the botanical origin and to evaluate the phenolic content and antioxidant properties (β-carotene/linoleic acid system, DPPH and ABTS scavenging) of mandaçaia geopropolis. 25 pollen types from 15 families were identified from the 9 geopropolis samples analyzed. Phenolic compounds content varied between all the geopropolis EtOH extracts, hexane, EtOAc and MeOH:H2O fractions. The main pollens found in the geopropolis samples were from the Leguminoseae family. This identification of meliponicultural plants is extremely important because it indicates the food sources used for the collection of nectar and pollen. Our results revealed that there is a strong relation between the phenolic compounds and the antioxidant activity. These results showed that total phenols of mandaçaia geopropolis may be responsible for the antioxidant activity with evidence that it's a rich source of phenols bioactive compounds with potential health benefits.

Effect of the Plastic Cover on the Productivity and Profitability of Vineyard in the São Francisco River Valley, Brazil

Abstract Data from field experiments conducted in vineyards table grape variety of Festival in Petrolina-PE, from October/2009 to November/2010, were used to evaluate the influence of the plastic cover on productivity and economic profitability of the viticulture in the São Francisco River Valley. Three treatments were studied: uncovered canopy (UC), plastic cover placed at 50 cm above the canopy (PC50), and a plastic cover placed at 100 cm above the canopy (PC100). The results indicated that the increased supply of radiative fluxes at the height of the berries in the treatment PC100 contributed to higher productivity, while treatment PC50 had the lowest offer of irradiative fluxes at the height of berries and much lower productivity. The yield obtained in the treatment PC100 exceeded 11 t ha-1 and 12.3 t ha-1 to those of treatments at UC and PC50, respectively. Treatment PC100 also had the lowest amounts of defects of berries, which contributed to higher total revenue. By contrast, treatment PC50 had markedly lower productivity, which represented considerable economic losses.

Presence of organic pollutants in the São Francisco river and its compartments

There has been great concern about the presence of organic pollutants in the environment. These types of compounds can be found in different types of habitats and have long term and deleterious effects on all living beings. The main objective of this study was to verify the presence of organic pollutants in different compartments of the Sao Francisco river. Fourteen sites were sampled since right after its springs till marginal lagoons in Pirapora City. The fine sediment was subject to the soxhlet extraction. The extracts were measured in a spectrophotometer in the absorbance range of 589 nm, which correspond to a yellow spectrum that correspond to the extraction of the organic pollutants. The organic matter of the sediments was measured. There was a positive correlation between organic matter content and the absorbance in the yellow color. However, both organic matter content and absorbance did not correlate with the distance from the spring. Even though was not possible to measure which organic pollutants were present in the sediments of the different compartments of the Sao Francisco river, the results of this study clear indicates the presence of these compounds in the samples. The correlation of the organic matter content and the absorbance showed that the organic matter is a important constituent in the sequestration of the organic pollutants. More studies should be conducted to determine which types of compounds are present in these sediments and if there is transfer of these organic pollutants in the aquatic food chain.