Jamari River Research Articles

A landscape ecology approach: Modeling forest fragmentation with artificial neural networks and cellular‐automata Markov‐chain for improved environmental policy in the southwestern Brazilian Amazon

AbstractLand degradation and forest fragmentation have been prominent issues in the Amazon since the 1970s, primarily driven by the suppression of primary forests due to land use changes. In this study, we propose an innovative approach by integrating artificial neural networks (ANN) and cellular automata Markov chain (CA‐MA) models to predict future land use and assess the associated forest fragmentation using landscape ecology metrics in the Jamari River Basin. The analysis reveals a significant increase in fragmentation between 1985 and 2018, as evidenced by a rise in the number of fragments from 7162 to 28,170. Moreover, we observed a decrease in the core area from approximately 2.5 million hectares to less than 1 million hectares, accompanied by an increase in edge density from 6 to 18 m.ha−1. Additionally, the average distance between fragments expanded from 66 to 95 m. Highlighting the urgency of addressing this issue, our study emphasizes the necessity of exploring effective strategies within the Brazilian public environmental management system. By utilizing various rural policy planning tools, we aim to tackle unsustainable development and mitigate the adverse impacts of land use changes in the region. In conclusion, this research offers an innovative approach that combines ANN and CA‐MA models to predict land use and assess forest fragmentation, shedding light on the alarming trend of land degradation and providing valuable insights for informed decision‐making and sustainable land management practices.

Watershed Level Sustainable Development Index in Rondônia, Western Amazon

Objective: to build a sustainable development index for the river basins of Rondônia, using factor analysis as an analytical model. Method: factor analysis was used as a tool for building environmental, economic, social and institutional performance indices. The adapted FECAM classification scale was adopted to express the results achieved by each river basin. Results: The set of current sustainable performance indices for the Mamoré River watersheds (0.444) was considered a low index, although the best compared to other basins; the Madeira River (0.419, low index); the Guaporé River (0.378, low index); the Machado River (0.289, low index); the Jamari River (0.307, low index) and the Roosevelt River (0.227, low index). There has been a really insignificant improvement in the rates from 10 years ago. Conclusions: the factor analysis showed efficiency as a multivariate statistical method in the construction of sustainable development indices for the river basins of Rondônia. The management of watersheds is still very ineffective, despite being regulated by state law. It is highly recommended to institutionalize regional public policies in the form of a Master Plan for the Rondônia Watershed.

A new species of the Nuneztovari Complex of Nyssorhynchus (Diptera: Culicidae) from the western Brazilian Amazon.

Nyssorhynchus (Nyssorhynchus) jamariensis, a new species of the Nuneztovari Complex, previously known as Anopheles (Nyssorhynchus) nuneztovari A, is described and validated using morphological characters of the adult male and female, male genitalia and immature stages. The species is recorded from the western Brazilian Amazon, where it was collected in pastures in the vicinity of the Jamari River, municipality of Monte Negro, Rondnia State, Brazil. Illustrations of the male genitalia, fourth-instar larva and pupa are provided. Nyssorhynchus jamariensis may be involved in malaria transmission, but its vector status needs further investigation.

Influence of Iron on Physiological Parameters and Intracellular Microcystin in Microcystis Panniformis Strain Isolated from a Reservoir in the Amazon.

In the Amazon, the leaching from soil left unprotected by deforestation increases the entry of iron, among other elements, in aquatic ecosystems, which can cause cyanobacterial blooms. This study aimed to investigate the physiological response of a strain of Microcystis panniformis to iron variation. The strain was isolated from a reservoir located in the Western Amazon and produces microcystin-LR. After a period of iron deprivation, the cultures were submitted to three conditions: control (223 μgFe.L-1), treatment with 23 μgFe.L-1, and absence of iron. At regular intervals for eight days, the cell density, levels of chlorophyll a and microcystins were determined. On the second and fourth day, transcription of genes responsive to iron limitation was quantified. Starting on the fourth day of the experiment, the different iron concentrations affected growth, and on the eighth day in the iron-free condition cell density was 90% lower than in control. Chlorophyll cell quota in 23 μgFe.L-1 and control presented similar values, while without iron the cells became chlorotic as of the fourth day Toxin concentration in cells grow in 0 μgFe.L-1 in relation to the control. Higher transcription levels of the feo and fut genes were observed in the 0 μgFe.L-1 and 23 μgFe.L-1 treatments, indicating that the cells were activating high-affinity capture systems to reestablish an adequate concentration of intracellular iron. The increasing deforestation in the Jamari River Basin (Amazon region), can contribute to the occurrence of toxic cyanobacterial blooms due to the greater entrance of iron in water bodies.

Checklist of the fishes from Jamari River basin, in areas under influence of dams, Rondônia, Brazil

Abstract: The Madeira River is the most extensive tributary of the Amazon River and has the largest diversity of fishes in the world. On its right bank, the Madeira River receives the Jamari River, in which the first hydroelectric power plant (HPP) in State of Rondônia, Samuel HPP, was built. Besides this, other dams were built in the Jamari River and its tributaries, however, the available information in the scientific literature about the ichthyofaunistic diversity of this basin is rare. This work aims to provide an ichthyofaunistic inventory in a region of the Jamari river basin, in the State of Rondônia, where three small hydropower plants (SHPs) were implemented. The ichthyofauna was sampled in 16 expeditions between August 2015 and December 2018. Gill nets and seine nets were used with different meshes, as well as longlines and cast nets at different times of the day. Additionally, 81 INPA lots of species from the Samuel HPP area of influence were reanalyzed. Fish were identified according to the specialized literature, as well as in consultations with experts of various taxonomic groups. Voucher specimens of the species were cataloged and deposited in the ichthyological collection of the Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura (Nupélia) of the Universidade Estadual de Maringá. A total of 230 species were recorded, of which 22 were putative new species, 117 were added to the Jamari River basin and 28 to the Madeira River basin. The continuation of the studies in this section of the Jamari river basin is fundamental for analysis of local impact due to the presence of dams. Moreover, the addition of putative new species to the Madeira River basin indicates gaps in the knowledge of Neotropical ichthyofauna.

Wildlife species, Ixodid fauna and new host records for ticks in an Amazon forest area, Rondônia, Brazil.

The objective of this work was to evaluate the diversity of ticks associated with free-living animals and to investigate new host records for ticks. Ticks were collected from animals rescued during the flood of the Jamari River in the municipality of Ariquemes, state of Rondônia, North Region of Brazil. A total of 39 animals were captured, out of which 10 were amphibians, 19 were reptiles and 10 were mammals. A total of 127 ticks of the Amblyomma genus were collected from these animals, distributed among seven species: Amblyomma dissimile, Amblyomma geayi, Amblyomma humerale , Amblyomma longirostre, Amblyomma nodosum , Amblyomma rotundatum and Amblyomma varium. In addition, one specimen of Rhipicephalus (Boophilus) microplus was collected. Among these specimens, 85 were adults and 42 were nymphs, with A. rotundatum being the most prevalent species. An Amblyomma spp. larvae was also collected from a lizard (Uranoscodon superciliosus), and one Amblyomma calcaratum and one Amblyomma dubitatum were recovered from the environment, thus totaling 130 ticks. Among the Ixodidae collected from different hosts, we provide the first report for the species A. rotundatum parasitizing Rhinella major, U. superciliosus, Leptophis ahaetulla, Chironius multiventris, and Mastigodryas boddaerti, as well as of A. humerale parasitizing U. superciliosus, A. geayi parasitizing Choloepus didactylus, and Rhipicephalus (B.) microplus parasitizing Alouatta puruensis.

Spatial-temporal dynamics and sources of total Hg in a hydroelectric reservoir in the Western Amazon, Brazil

Damming rivers to construct hydroelectric reservoirs results in a series of impacts on the biogeochemical Hg cycle. For example, modifying the hydrodynamics of a natural watercourse can result in the suspension and transport of Hg deposits in the water column, which represents an exposure risk for biota. The objective of this study was to evaluate the influences of seasonality on the dispersion of total Hg in the Hydroelectric Power Plant (HPP)-Samuel Reservoir (Porto Velho/Brazil). Sampling campaigns were performed during the three following hydrological periods characteristic of the region: low (Oct/2011), ebbing (May/2012), and high (Feb/2013) water. Sediment profiles, suspended particulate matter (SPM), and aquatic macrophytes (Eicchornia crassipes and Oryza spp.) were collected, and their Hg concentrations and isotopic and elemental C and N signatures were determined. The drainage basin significantly influenced the SPM compositions during all the periods, with a small autochthonous influence from the reservoir during the low water. The highest SPM Hg concentrations inside the reservoir were observed during the high water period, suggesting that the hydrodynamics of this environment favor the suspension of fine SPM, which has a higher Hg adsorption capacity. The Hg concentrations in the sediment profiles were ten times lower than those in the SPM, indicating that large particles with low Hg concentrations were deposited to form the bottom sediment. Hg concentrations were higher in aquatic macrophyte roots than in their leaves and appeared to contribute to the formation of SPM during the low water period. In this environment, Hg transport mainly occurs in SPM from the Jamari River drainage basin, which is the primary source of Hg in this environment.

Potamotrygon limai, sp. nov., a new species of freshwater stingray from the upper Madeira River system, Amazon basin (Chondrichthyes: Potamotrygonidae).

Potamotrygon limai, sp. nov., is described from the Jamari River, upper Madeira River system (Amazon basin), state of Rondônia, Brazil. This new species differs from congeners by presenting unique polygonal or concentric patterns formed by small whitish spots better defined over the posterior disc and tail-base regions. Potamotrygon limai, sp. nov., can be further distinguished from congeners in the same basin by other characters in combination, such as two to three rows of midtail spines converging to a single irregular row at level of caudal sting origin, proportions of head, tail and disc, patterns of dermal denticles on rostral, cranial and tail regions, among other features discussed herein. Potamotrygon limai, sp. nov., is most similar to, and occurs sympatrically with, P. scobina, and is distinguished from it by lacking ocellated spots on disc, by its characteristic polygonal pattern on posterior disc, a comparatively much shorter and broader tail, greater intensity of denticles on disc, more midtail spine rows at tail-base, and other features including size at maturity and meristic characters. Potamotrygon limai, sp. nov., is also distinguished from other species of Potamotrygon occurring in the Amazon region, except P. scobina, by presenting three angular cartilages (vs. two or one). This new species was discovered during a detailed taxonomic and morphological revision of the closely related species P. scobina, and highlights the necessity for thorough and all-embracing taxonomic studies, particularly in groups with pronounced endemism and morphological variability.

AVALIAÇÃO DA QUALIDADE DAS ÁGUAS SUPERFICIAIS DO RIO JAMARI NA REGIÃO DA CONSTRUÇÃO DE UMA PCH NO MUNICÍPIO DE MONTE NEGRO-RONDÔNIA, AMAZÔNIA OCIDENTAL

With the construction of a SHP (small hydro) in the course of the Jamari River in the town of Monte Negro RO becomes important monitoring of surface waters of the Rio Jamari to assess your current situation during the process of implementing the SHP to subsequently assess the impact caused the river by construction. The present paper has aimed at the evaluation of the water quality of the Rio Jamari, evaluating standards physico-chemical, microbiological, phytoplankton and ichthyoplankton, where after evaluating all the parameters generated up the WQI (Water Quality Index), which was between 68-79%, assessed at four points in the course of the river, indicating a good quality water, within the parameters of evaluable IQA. The values ZAN et al., v(8), no 8, p. 1876-1888, SET-DEZ, 2012. Rev. Elet. em Gestao, Educacao e Tecnologia Ambiental (e-ISSN: 2236-1170) http://cascavel.ufsm.br/revistas/ojs-2.2.2/index.php/reget 1877 obtained were considered satisfactory in view of the Jamari River is a river that has suffered a lot from the process of deforestation in the region, deploying mines and plantations.

Adaptation of the Micronucleus Technique in Allium Cepa, For Mutagenicity Analysis of the Jamari River Valley, Western Amazon, Brazil

This study aimed to make technique adjustment of micronuclei in Allium cepa, recommended by Fiskejo [1], by replacing methanol and Giemsa by triarilmetano the 0,1%, xantenos the 0,1% and tiazinas the 0,1%. We obtained good results with the replacement, as its efficiency in stain nucleic acids, obtaining a good visualization of cells, mitotic index, micronuclei, anaphase and telophase bridges, and this methodology is indicated in future examinations of mutagenicity in the river Vale do Jamari.

Mineralogia e química dos sedimentos de fundo do médio e baixo Madeira e de seus principais tributários: Amazonas - Brasil

O objetivo deste trabalho foi investigar a variação composicional e mineralógica dos sedimentos de fundo transportados pelos grandes rios da Amazônia, com nascentes nos Andes provenientes de rochas cratônicas. O estudo foi realizado com base em análises granulométricas, mineralógicas e químicas, incluindo isótopos de Pb, no rio Madeira e seus tributários. O conjunto de dados mostra que os sedimentos de fundo do rio Madeira são granulométrica, mineralógica e quimicamente distintos de seus principais tributários. Os sedimentos do rio Madeira são mais arenosos; têm maior quantidade de quartzo; menor conteúdo de Al2O3, Fe2O3, K2O, MgO, Na2O, PF, TiO2, P2O5, MnO e elementos-traço; e a maturidade aumenta de montante para jusante. Dentre os sedimentos dos tributários, os rios Machado e secundariamente o rio Marmelos são os que mais se aproximam da composição dos sedimentos do rio Madeira, enquanto que o Jamari com sedimentos com maior proporção de TiO2, Zr, Y, Nb, Ga, Hf, U, Ta e ETR, é o mais distinto. Apesar do ambiente de intenso intemperismo e erosão, em condições tropicais úmidas, a que estão submetidas as rochas drenadas pela bacia do rio Madeira, os valores das razões Th/Co, Th/Pb, Th/Yb, Al/Pb, Zr/Co e a composição isotópica de Pb indicam fontes distintas para os sedimentos de fundo estudados. Os sedimentos do rio Madeira são provenientes, principalmente, de rochas máficas, enquanto que os sedimentos de seus tributários têm como fonte essencialmente rochas félsicas.

Novel sources of witches’ broom resistance (causal agent Moniliophthora perniciosa) from natural populations of Theobroma cacao from the Brazilian Amazon

Witches' broom is a severe disease of Theobroma cacao L. (cacao), caused by the basidio- mycete Moniliophthora perniciosa. The use of resistant cultivars is the ultimate method of con- trol, but there are limited sources of resistance. Further, resistance from the most widely used source ('Scavina 6') has been overcome after a few years of deployment. New sources of resistance have been intensively searched for in the Amazon basin. Here, we evaluated for witches' broom resistance, cacao accessions from various natural cacao populations originally collected in the Brazilian Amazon. Resis- tance of 43 families was evaluated under nursery and/ or field conditions by artificial or natural infection, respectively, based on disease incidence. Screening for resistance by artificial inoculation under nursery conditions appeared to be efficient in identifying these novel resistance sources, confirmed by natural field evaluation over a nine-year period. The increase in natural field infection of 'Scavina 6' was clearly demonstrated. Among the evaluated families with the least witches' broom incidence, there were accessions originally collected from distinct river basins, includ- ing the Jamari river ('CAB 0371'; 'CAB 0388'; 'CAB 0392'; and 'CAB 0410'); Acre ('CAB 0169'); Javari ('CAB 0352'); Solimoes ('CAB 0270'); and from the Purus river basin, the two most outstanding resistant accessions, 'CAB 0208' and 'CAB 0214'. The large genetic diversity found in cacao popula- tions occurring at river basins from Acre and Amazonas states, Brazil, increased the chance that the selected resistant accessions would be genetically more dissimilar, and represent distinct sources of resistance to M. perniciosa from 'Scavina 6'.

Conserved Cytogenetic Features in the Amazonian Arapaima, Arapaima gigas (Schinz 1822) from Jamari River, Rondônia–Brazil

Specimens of Arapaima gigas from Jamari River (RO) were cytogenetically analyzed. A diploid number of 2n=56 chromosomes was found (28m-sm + 28st-a). Secondary constrictions were observed on the short arms of chromosome 3. Nucleolar Organizer Regions (NORs) were detected at the subterminal region on short arms of the third chromosomal pair by both silver nitrate staining and FISH with 45S rDNA probe, being equivalent to secondary constrictions. The ribosomal sites were also characterized by size heteromorphism and presence of CMA3+/DAPI- blocks. The constitutive heterochromatin was located at pericentromeric region of some chromosomes. After sequential Cbanding and base-specific fluorochromes staining, most of the heterochromatins proved to be neutral, i.e., with similar amounts of AT and GC bases. Nonetheless, some heterochromatic regions were marked by GC-specific fluorochromes in one chromosomal pair and by AT-specific fluorochrome staining on two pairs. The present data are in agreement with previous reports in populations from Araguaya River, indicating that conserved cytogenetic features are present in this important fish species.

Physical and chemical post-dam alterations in the Jamari River, a hydroelectric-developed river of the Brazilian Amazon

The regulation of the Jamari River advanced peak floods by 1–2 months and increased dry-season discharges from 60 to 200 m3 s−1, resulting in water levels approximately 1 m above those recorded before regulation. Daily variation in water level associated with fluctuations in electricity production by the dam propagated to the lower reaches of the tributary Candeias River. Dissolved oxygen (DO), temperature, pH, and conductivity measured over 1.5 years on three locations along the regulated and two free-flowing rivers indicated important alterations in the case of oxygen concentrations. DO levels shifted from saturated (7–8 mg l−1) during the flood season (when the spillways were open releasing epilimnetic water) to hypoxic (1.5–3 mg l−1) during the dry season (when the floodgates were closed and only hypolimnetic water used to run the turbines was feeding the river). Fluctuations in water level and variation in dissolved oxygen tended to be greater at the site closest to the dam, gradually attenuating downstream. Mitigation of the downstream effects of river regulation would require modifications in the operation of the dam.

Protein electrophoretic variability in Saimiri and the question of its species status.

An electrophoretic survey of 15 protein systems (22 loci) was employed to determine the genetic relationships among 9 populations (441 individuals) of South American squirrel monkeys (Saimiri sciureus sciureus, S. sciureus boliviensis, and S. sciureus ustus). Genetic markers capable of differentiating the second from the two other taxa were observed mainly in the ADA and GPI systems. Heterogeneity for ADA and CA2 between populations from opposite banks of the Jamari river was verified in S. sciureus ustus. The average heterozygosities ranged from 3% to 5%, the lowest being in S. sciureus sciureus and the highest in S. sciureus boliviensis. Low genetic distances (D = 0.001-0.057) were observed between populations within taxa or between S. sciureus sciureus and S. sciureus ustus. But both differed to a larger extent from S. sciureus boliviensis (D = 0.11 in both comparisons). There is a positive correlation between the genetic and geographic distance matrices. The three taxa are more clearly separated (D = 0.76-0.77) from the outgroup used for comparison (Cebus apella). Our data suggest that there is only one large, polytypic species of squirrel monkeys in South America, S. sciureus, forming a contiguous ring of geographical races or subspecies. Two of the most differentiated forms meet at the Peruvian Amazonia where natural hybrids and secondary intergradation have been reported. © 1993 Wiley-Liss, Inc.

Hydrological and geochemical characteristics of the Jamari and Jiparana river basins (Rondonia, Brazil)

The authors investigate the hydrological and geochemical characteristics of the Jamari (30430 km2) and Jiparana (60350 km2) river basins (Amazonia), during the period 1978–1984. A spectral analysis of Fourier is applied to time series of mean monthly river discharges, in order to assess the contribution (7 to 8%) of the surface runoff to the total river flow. The mean annual runoff coefficient calculated for the Jiparana river basin (36%), is higher than for the Jamari (32%), and this coefficient increases during the study period, only for the Jiparana. The total specific suspended sediment discharge calculated for both rivers shows the same value 13 t/km2/y, and the estimated suspended sediment concentration in the surface runoff is slightly superior for the Jiparana river (0.3 g/l) than for the Jamari one (0.2 g/l). The river suspended sediments are mainly composed of kaolinite, quartz and feldspar, but the Jiparana is more enriched in quartz. For both rivers, the dominant clay mineral is the kaolinite which is in agreement with the rock weathering type determined for both basins using the Tardy's weathering index: the monosiallitisation. The total chemical erosion rate calculated after correction for the atmospheric inputs (ions and CO2), is higher for the Jiparana (10.11 t/km2/y) than for the Jamari river basin (7.75 t/km2/y). These values are lower than the mechanical denudation rate calculated previously for both river basins.

Development and erosion in the Brazilian Amazon: A geochronological case study

A 210Pb chronology of sedimentation in a small floodplain lake in the Jamari river basin (Rondonia, Brazil) provided insight into the relationship between development and erosion in the Brazilian Amazon. Positive correlations between increased sedimentation in the lake and levels of deforestation and mining in the Jamari basin suggested a major increase in erosion associated with these activities. This increase in erosion could diminish agricultural yields in the basin and significantly reduce the useful life of a hydro-electric plant recently built on the river.