Tapajos River Basin Research Articles

Local trade, spatial occurrence and conservation of hypostomus soniae (siluriformes, loricariidae), an ornamental fish endemic to the tapajos river, Brazil.

Hypostomus soniae is a small sized armored catfish endemic to the Tapajos River basin and ranked as one of the most exploited ornamental fish in the Santarem export marketplace. This study aims to evaluate distributional patterns of Hypostomus soniae and contribute to the species conservation in the face of development of the ornamental fish trade in the Amazon region. We compiled data associated with geographic coordinates in public repositories, supplemented with original field records. We compared our data to published records in the literature and museum collections to check for accuracy. To investigate the fishery and commercialization of H. soniae, we conducted interviews with ornamental fish stakeholders from the local trade. We also made direct observations in the fishing sites and export facilities in Santarem. A cluster analysis of the geolocation data was carried out to explore the spatial distribution patterns. The volume of captures and exportation of H. soniae decreased during the period 2020-2023. The occurrence of H. soniae was associated with annual rainfall ranging from 2,000 mm to 2,500 mm and concentrated in two municipalities of the State of Mato Grosso and two of the Para State. The species distribution area has been threatened, unfortunately, by fishermen who do not respect the laws that support artisanal fishing in the Amazon.

A new species of Geophagus (Teleostei: Cichlidae): Naming a cichlid species widely known in the aquarium hobby as 'Geophagus sp. Tapajos red head'.

A new species of Geophagus sensu stricto is described from the Tapajos River basin, Brazil, elevating the number of species of the genus to 21. The new species is of commercial importance and is known in the aquarist trade as Geophagus 'red head'. The new species is diagnosed using an integrative approach, based on mitochondrial DNA analysis along with morphological evidence. The new species is distinguished from all congeners by the absence of markings on the head, the bar pattern composed by nine vertical bars on the flanks and the presence of distinct longitudinal bands in the caudal fin. Additionally, it shows a genetic distance of at least 2.0% in cytochrome b gene sequences from its closest congeners. Molecular analysis including most genera of Cichlidae from South America corroborates that the new species belongs to the group of Geophagus sensu stricto.

The fate of vegetation remnants in the southern Amazon's largest threatened hotspot: part (I) a 33-year analysis of LULCC in the Tapajos River basin, Brazil

In the present study, we evaluated the dynamics of native vegetation cover (NVC) fragmentation from 1985 to 2018 in the most threatened basin of the Rio Tapajos (TRB), a tributary of the Amazon River. The study sought to understand how land use pressures negatively impacted the remnants of the agricultural matrix and the biodiversity of local biotas. To this end, we created a sampling grid with hexagons of 50,000 hectares each, compartmentalized as follows: for the entire basin area, we used a grid of 1255 hexagons in the analyses; in the northern portion of the basin (Amazon biome), we used a grid with 965 hexagons and in the southern portion of the basin (Cerrado biome) we used a grid with 290 hexagons. In these grids, we apply six landscape ecology metrics: number, size, edge, isolation, remnants and interiority, unprecedented in landscape studies. The hexagons created were our analytical units in the study of isolation and habitat loss between forest remnants (Fo) and savannas (Sa) in the three defined Core Areas. The results showed that the fragmentation dynamics in TRB was not a single and isolated event in the three compartments analyzed, with different clusters in the studied portions. The number of remnants grew exponentially in the landscape, in the first 20 years of the study (1985- 2005), and their areas lost half their original sizes in both parts of the basin. Regardless of remnant size or typology, the edge effect was high in both small and large patches (Fo = 15% and Sa = 20%). The isolation of the remnants was greater and increasing in the northern portion of the basin, in 20 years (1985-2005), the isolation class 100 to 1000 meters increased 31% for the Fo patches, while the Sa patches increased only 11% in the southern part of the basin. The total losses of remnants (Fo+Sa) in the northern portion were 38% and 41% for the remainders of the southern portion of the basin. It is important to emphasize that this study is the largest assessment ever carried out in the entire area of an Amazon watershed, with the objective of creating a database for comparative studies with other threatened watersheds. Our analyzes showed that 60% of the TRB Plateau area was converted to planted pastures and annual crops. If the same rates of deforestation and fragmentation remain at the current level, the prognosis for 2040 will not be encouraging.

Investigation of lead sources in manioc flour from riparian communities in the Tapajós Region, Brazilian Amazon

From a previous pilot study, the Tapajos River basin riparian population was found to have elevated blood lead (PbB) levels, ranging from 0.59 to 48.3 μg/dL. Preliminary analyses of these results initially pointed to the metallic plates used in the production of manioc flour as a possible source. The main objective of this study was to investigate the potential environmental sources of Pb in the manioc flour in this region. The study was carried out in eight communities on the Tapajos River, where samples of manioc flour, metal plates and soil from manioc plantations were collected. In addition, samples of deposited sediments from the Tapajos River and its tributaries and riverbank sediments were collected. The metal composition was analyzed by SEM, XRF and GFAAS. The results show that the concentrations of Pb in manioc flour ranges from 0.08 to 0.31 mg/kg and the manioc paste from 0.004 to 0.037 mg/kg. The metallic plates used in the manioc-roasting process are made of carbon steel without Pb in the bulk alloy. Pb concentrations in soils where manioc roots were cultivated range from 8.9 to 26.1 mg/kg and Zn concentrations range from 12.7 to 59.1 mg/kg, indicating a contribution of polymetallic geological deposits. The clay-rich samples have high metal contents (including Pb, Zn and Cu). The Pb content of the clay samples ranges from 10.6 to 25.1 mg/kg. These results suggest that it is unlikely that the Pb found in the manioc flour originates from the metal plates used in its roasting process, rather, it seems to be associated to environmental factors determined by the local geology and soil composition.

Por uma vida sem barragens: corpos, território e o papel da autodeterminação na desnaturalização da violência

Partindo do emblemático contexto de (r)existência munduruku e ribeirinha à tentativa de imposição das barragens de São Luiz e Jatobá, na bacia do rio Tapajós, entre 2013 e 2015, procuro traçar uma perspectiva analítica capaz de apreender como o caráter substantivo da lógica de progresso/desenvolvimento, identificada com o Estado, vem a tomar corpo nos embates cotidianos, envolvendo diferentes atores sociais. Identifico dois modos distintos por meio dos quais tal lógica opera: o rumor — que, como coloca Veena Das, caracteriza a efetivação do que é apenas potencialidade —, e a não performatividade — em que, diversamente, de acordo com Sara Ahmed, a enunciação vem a substituir a ação. Conforme sugiro, a persistência dos povos munduruku e ribeirinho em seu próprio processo de autodeterminação cole(a)tiva mostrou-se fundamental a fim de possibilitar a desnaturalização da violência subjacente à lógica de progresso/desenvolvimento, expondo sua intencionalidade antes de que o megaempreendimento viesse a se tornar “fato consumado”, de forma a permitir o florescimento de modos específicos de (r)existências que lhe fizessem frente, mesmo sob enorme disparidade em termos de correlação de forças.

Distribution of rainfall probability in the Tapajos River Basin, Amazonia, Brazil

Studies on the probability of rainfall and its spatiotemporal variations are important for the planning of water resources and optimization of the calendar of agricultural activities. This study identifies the occurrence of rain by first-order Markov Chain (MC) and by two states in the Tapajos River Basin (TRB), Amazon, Brazil. Cluster analysis (CA), based on the Ward method, was used to classify homogeneous regions and select samples for checking the probability of rainfall occurrence by season. The historical series of daily rainfall data of 80 stations were used for the period 1990-2014. The CA technique identified 8 homogeneous regions and their probability of occurrence of rainfall, helping to determine which regions and periods have greater need of irrigation. Results of the probability of occurrence of dry and rainy periods in the TRB were used to define the dry (May thru September) and rainy seasons (October thru April). Elements of the matrix transition probabilities showed variability in relation to time and, in addition, the influence of geographical position of seasonal rainfall in determining dry and rainy periods at specific sites in the TRB.

Evaluation of MODIS-based estimates of water-use efficiency in Amazonia

ABSTRACTThis study aimed to assess the spatial-temporal patterns of water-use efficiency (WUE) obtained through MODIS gross primary productivity (GPP) and evapotranspiration (ET) products (MOD17 for GPP and MOD16 for ET) in the Upper Tapajos and Curua-Una River basins, located in the oriental flank of the Amazon region, and to validate the results with flux tower measurements within the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) project. The spatial variation of WUE was primarily related to the larger presence of forested areas in the Upper Tapajos River basin (western part) compared with the Curua-Una River basin (eastern part), which is situated within the so-called arc of deforestation. Temporally, WUE showed a pronounced seasonal pattern, varying with the dry and wet seasons in the region. A decrease of ~3% in WUE was observed during the dry season, which was related to the low water availability and increased vapour pressure deficit during the dry period, which induces stomatal closure, leading to a decline in the photosynthetic rate. Comparison between the WUE estimates obtained by MODIS data and observations from the LBA towers showed an average error of 17%, varying between ~12% and ~28% for the different sites. MODIS WUE depends on the accuracy of both GPP and ET estimation. In this sense, we highlight that improvements in both MODIS GPP and ET products are necessary and should focus on reducing the uncertainties related to the biophysical vegetation parameters and meteorological data that serve as input information in the algorithms.

Metazoan Parasites of <i>Geophagus proximus</i>, a Cichlidae Fish from the Eastern Amazon (Brazil)

The present study investigated the fauna of metazoan parasites of a Geophagus proximus population from the lower Tapajos River, in the state of Para, northern Brazil. A total of 137 monogeneans were collected from the gills of G. proximus, including Sciadicleithrum kritskyi, Sciadicleithrum paranaensis and Sciadicleithrum geophagi, while 119 Raphidascaris (Sprentascaris) lanfrediae nematodes and 28 metacercariaes of digenea undetermined were collected from the intestine. Hosts harboring four species of parasites were predominant. The parasites had an aggregated dispersion pattern. The present study represents the first record of S. geophagi parasitizing G. proximus, increasing the geographic distribution of these parasite species to the Tapajos River basin.

Water level forecasting and navigability conditions of the Tapajós River - Amazon - Brazil

In the Amazon, hydrological modelling is of great importance to the safety and operation of inland waterway transport. In this paper, a stochastic model named ARIMA (Autoregressive Integrated Moving Average) was used to forecast water levels and seaworthiness 24 months in advance in the Tapajos River. Additionally, a time series analysis aimed to model and predicting water levels in the Tapajos river basin was completed. During validation, the model had an average coefficient of Nash and Sutcliffe R² of 0.95 and an average RMSE of 0.06. Drought forecast for the model predicted depth gains of 30 cm and a load capacity gain of 2,800 tons per trip. In the analysis of the two seasonal periods, the model predicted annual savings in freight cost of U.S. $350,000.00. The performance of the model allows us to conclude that ARIMA models should be used to forecast water levels and navigation conditions in the Amazon.

Length-Weight Relationships for Fish Fauna from Waterbodies in the Upper Tapajós River Basin of Palito Mountain Ridge, Brazilian Amazon Region

Length-weight relationships (LWR) of 14 fish species were estimated from Palito Mountain ridge, upper Tapajos river basin, Brazilian Amazon region. This study represents the first LWR to the small characid Hemigrammus marginatus , and additionally provides new maximum record of length and weight for four and three species, respectively. Keywords: Neotropical freshwater fish fauna; Length-weight relationship; Tapajos river basin; Allometry

Plasma Phospholipid Omega-3 Fatty Acids and Freshwater Fish Consumption in the Brazilian Amazon

Background: Amazonian riverside communities consume large quantities of freshwater fish, comparable to marine fish consumption of Inuit, Scandinavian and Japanese populations. Few studies have considered the relation of high freshwater fish consumption and intake of omega-3 fatty acids (FA). Objective: The objective of the present study was to determine the profile of the concentrations of plasma phospholipid FAs and its relation with freshwater fish intake in 12 riverside communities in the Tapajos River basin (State of Para, Brazilian Amazon). Design: This cross-sectional study included 333 adults (15 - 86 years old). Fish meal frequency was determined using a 7-day interview-administered dietary recall questionnaire. Fish were categorized as piscivorous and non-piscivorous fish on trophic level. Plasma phospholipid FAs were measured by capillary gas-liquid chromatography. Results: Participants consumed 5 to 6 fish meals a week, with twice as many non-piscivorous fish than piscivorous fish (4.4 fish/week vs 2.2 fish/week, respectively). The omega-3 FA levels in plasma phospholipids were low (EPA + DHA = 31.21 mg/L; %EPA + DHA = 2.59%). Omega-3 FAs increased with frequency of fish intake, and particularly with piscivorous fish, controlling for sociodemographic, anthropometric and lifestyle characteristics. DHA levels were greater in women than in men. Conclusions: Omega-3 FA in this Amazonian population increased with fish consumption, but although they consumed freshwater fish almost daily, the concentrations of omega-3 FA were relatively low and comparable to fish-eater communities for which fish is not a dietary mainstay. It is possible that nutrients present in marine, but not in certain freshwater fish species, may facilitate absorption of omega-3 FA. Sex and/or gender differences must be taken into account when assessing the relationship between fish consumption and plasma phospholipid omega-3 FA levels.

Policies and regulations for Brazil’s artisanal gold mining sector: analysis and recommendations

In Brazil, artisanal and small-scale gold mining (ASGM) produces in the range of 6 tonnes of gold (Au) per annum, and employs approximately 200,000 people. Most of this mining activity is in the Amazon region, where miners have been extracting gold for more than 40 years. In the Tapajos River Basin, assessments indicate that around 99% of miners operate without the environmental and mining permits required by law. This is a result of a combination of unrealistic or lack of proper policies and regulations, lack of political will, lack of infra-structure to enforce the existing regulations and lack of incentives to miners to comply with legal requirements. In this article, we analyze a group of 20 laws, decrees and resolutions in Brazil, focusing on how idiosyncrasies in these regulations reveal gaps between policy and reality in ASGM areas. Artisanal miners operate in vast and remote areas and the government lacks the resources (personnel, vehicles, information and materials) to enforce the laws. Our analysis emphasizes the need for creating new government commitments and identifying priority areas where government agents can focus their efforts. There is no single solution for the environmental, health, technical and socio-economic problems associated with ASGM. However, a realistic approach should consider improving the level of education of miners, creating government programs to provide technical assistance in the field, simplifying administrative procedures and ensuring adequate measures for enforcement.

Strategies for reducing the environmental impact of reprocessing mercury-contaminated tailings in the artisanal and small-scale gold mining sector: insights from Tapajos River Basin, Brazil

Worldwide, the environmental impacts of artisanal and small-scale gold mining (ASGM) are extensive. Annual losses from mercury, which is used to amalgamate gold, are in the range of 1000 tonnes, and at advanced sites, there is the additional threat of cyanide contamination. Recent developments in The Brazilian Amazon, an area populated by 200,000 small-scale gold miners, have the potential to reduce these impacts considerably. In the locality of Garimpo Ouro Roxo, miners are presently using amalgamation and cyanidation in vat-leaching. Each cycle typically recovers 50% of the gold and lasts 20 days (per tank), consuming around 3300 kg NaCN/month. A new process has been developed and implemented in a pilot plant in this area, involving gravity concentration followed by cyanidation in a ball mill. Concentrate leaching is conducted with a PVC capsule filled with activated carbon inserted in the cyanide solution in the mill. The cycle takes less than 24 h and recovers up to 98% of the gold in the concentrate. The main advantages of wide adoption of this method, apart from a reduced gold recovery cycle and improved recovery, include possible phase out of amalgamation altogether, and marked reductions in cyanide consumption (from current 22,000 kg–980 kg annually).

Using Performance Indicators to Evaluate an Environmental Education Program in Artisanal Gold Mining Communities in the Brazilian Amazon

The Tapajos River Basin in the Brazilian Amazon is the location of one of the largest concentrations of artisanal and small-scale miners in the world. Today, 40,000 miners produce 8 t of gold annum(-1) and at least double this amount of mercury is released into the environment. This region was selected under the Global Mercury Project, a United Nations program that aims to reduce the environmental and health impacts caused by mercury through the application of cleaner technologies and increased awareness. A group of educators provided support to miners, training 4200 people in 141 mining locations. The effectiveness of this training was evaluated based on 20 performance indicators. After 120 days of training, an absolute improvement of approximately 29% had been achieved. As a result of this training, it is estimated that annual mercury emissions in Tapajos have been reduced by 1762 kg or around 10% of the total mercury released in the region.

Daily hydrological modeling in the Amazon basin using TRMM rainfall estimates

Summary Rainfall measurements by conventional raingauges provide relatively accurate estimates at a few points of a region. The actual rainfield can be approximated by interpolating the available raingauge data to the remaining of the area of interest. In places with relatively low gauge density such interpolated rainfields will be very rough estimates of the actual events. This is especially true for tropical regions where most rainfall has a convective origin with high spatial variability at the daily level. Estimates of rainfall by remote sensing can be very useful in regions such as the Amazon basin, where raingauge density is very low and rainfall highly variable. This paper evaluates the rainfall estimates of the Tropical Rainfall Measuring Mission (TRMM) satellite over the Tapajos river basin, a major tributary of the Amazon. Three-hour TRMM rainfall estimates were aggregated to daily values and were compared with catch of ground-level precipitation gauges on a daily basis after interpolating both data to a regular grid. Both daily TRMM and raingauge-interpolated rainfields were then used as input to a large-scale hydrological model for the whole basin; the calculated hydrographs were then compared to observations at several streamgauges along the river Tapajos and its main tributaries. Results of the rainfield comparisons showed that satellite estimates can be a practical tool for identifying damaged or aberrant raingauges at a basin-wide scale. Results of the hydrological modeling showed that TRMM-based calculated hydrographs are comparable with those obtained using raingauge data.

Mercury pollution in the Tapajos River basin, Amazon: Mercury level of head hair and health effects

There is increasing concern about the potential neurotoxic effects of exposure to methylmercury for the 6 million people living in the Amazon, even in regions situated far away from the gold mines (garimpos), considered to be the major source of mercury pollution. In November 1998, a spot investigation on mercury contamination was conducted in three fishing villages (Barreiras, Rainha, and Sao Luiz do Tapajos) on the Tapajos River, an effluent of the Amazon, situated several hundred kilometers downstream from the gold-mining areas. A total of 132 fishermen and their families volunteered for the current study. As was anticipated, the total mercury levels in the head hair collected from the fishing villages were relatively high (14.1–20.8 ppm on the average) and the number of subjects with a high total mercury level over 10 ppm (the least upper bound of a normal value) was 103 (78.0%) in total, along with various symptoms, thereby suggesting wide mercury contamination in the Tapajos River basin. Moreover, in view of the absence of other diseases (e.g., alcoholism or malaria), a high intake of fish containing a methylmercury level, and high hair mercury levels in addition to the various symptoms such as sensory disturbance (especially glove-and-stocking type, which is characteristic of Minamata disease), tremor, failure in two-point discrimination, and slight balancing failure, several subjects examined were diagnosed with mild Minamata disease. The findings obtained suggest, thus, that the mercury pollution in the Amazon should be crucially observed for head hair mercury level and health in a much broader region.

Human Exposure to Mercury and the Accumulation of Methylmercury that is Associated with Gold Mining in the Amazon Basin, Brazil.

In order to evaluate the extent of human exposure to mercury in the Amazon, in particular, in the Tapajos River basin, which is a site of extensive alluvial gold mining, we analyzed samples of human hair, blood and urine, as well as fish, collected from different areas for total levels of mercury and methylmercury. In fishing villages, the inhabitants were found to have accumulated mercury, mostly in the form of methylmercury, at abnormally high levels as the apparent result of consumption of local fish, with very little confounding exposure to inorganic mercury, including mercury vapor in the air. The people living near the main gold-mining areas had accumulated higher levels of methlymercury than people living far downstream from the gold-mining sites. Quite high levels of methylmercury were found in samples of hair from inhabitants of the fishing villages.

Increase of the background human exposure to mercury through fish consumption due to gold mining at the Tapajós River region, Pará State, Amazon.

Methylmercury (MeHg) is a well know human neurotoxic substance (Clarkson 1994; Watanabe and Satoh 1996). It is listed by the International Program of Chemical Safety (IPCS) as one of the six most dangerous chemicals in the world’s environment. The general population is primarily exposed to MeHg through fish consumption. Over 90% of Hg present in fish from the Tapajos river basin is MeHg (Akagi et al. 1994) although the source is usually inorganic Hg. In Brazi l ian gold mining (“gar impos”), e lemental Hg 0 (metallic) is used to amalgamate the fine particles of gold. About 3,000t of Hg has been released by “garimpos” between 1987 and 1994 into the Brazilian Amazon (Lacerda 1997). Approximately half of this total came from “garimpos” in the Tapajos river basin (Cid de Souza and Bidone 1994).

Fish contamination and human exposure to mercury in the Tapajós River Basin, Pará State, Amazon, Brazil: a screening approach.

In the Brazilian Amazon gold mining (“garimpos”), Hg is used to amalgamatefine gold particles from placer deposits., A 2:l or even greater Hg/Auamalgamation ratio were observed by Lacerda et al. (1995) from several“garimpos” in the Amazon. Hg loss from gold mining to local ecosystems wasestimated to reach 1,300 t in the Amazon, between 1980 and 1993 (Cid deSouza and Bidone, 1994). More than 50% of this Hg were used in “garimpos”located in the Tapajos river basin, in Para State, the most important gold miningarea in Northern Brazilian Amazon in the 80’s, when the peak in Amazon “goldrush” occurres. Generally, the released Hg° is incorporate into the riversediments. Environmental methylmercury (MeHg) arises largely, if not solely,from the methylation of inorganic mercury (Hg

Methylmercury pollution in the Amazon, Brazil

In order to evaluate the extent of environmental mercury pollution due to goldmining activities in the Amazon, concentrations of total mercury and methylmercury were determined for human hair and fish samples from five fishing villages located mainly in the Tapajos river basin. Abnormally high levels of mercury were found in human hair from Jacareacanga and Brasilia Legal located near the main goldmining area as well as from Tres Bocas facing the lake in Amapa state, whereas the levels were much lower in Ponta de Pedras, a long way downstream. The values of male samples were about twice as high as females even in the same family. The predominant form of mercury in hair samples was methylmercury (average 90%), while high hair mercury observed in goldminers and workers in goldshops was mostly in the inorganic form. Longitudinal analyses of long hairs from people in fishing villages showed fairly constant and continuous exposure to methylmercury at least over the last few years with seasonal variations. Fish contained relatively high levels of mercury (up to 3.82 ppm) mostly in the form of methylmercury and most of the fish from upstream and some from downstream exceeded the allowable level of 0.5 ppm in Brazil.