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A new species of Knodus (Characiformes: Characidae) from the Rio Cupari drainage, lower Rio Tapajós basin, Brazil
No full textA new species of Knodus is described from the rio Cupari drainage, a tributary from the right margin of the lower rio Tapajós, Pará State, Brazil. The new species differs from its congeners, except K. geryi, by having a dark basal blotch on each caudal fin lobe (vs. caudal fin lobes with sparse chromatophores, lacking basal blotches) and, with the exception of K. borki, K. heteresthes, and K. pasco, by having 10-12 scales around the caudal peduncle (vs. 13-15). Copyright © 2020 Magnolia Pres
The importance of the Amazonian hydrological memory to the La Plata Basin
Full text linkDuring the austral winter, when there is a greater frequency of the Low Level Jet east of the Andes, evapotranspiration in the southern portion of the Amazon Basin constitutes an important source of moisture to atmosphere and, consequently, contributes with ~ 1/4 of precipitation over the La Plata Basin. As the southern Amazon receives less precipitation during the austral winter, the moisture previously stored in the deep soil during the rainy season sustains the evapotranspiration during the relatively dry season. Thus, the present doctoral thesis is based on the hypothesis that the hydrological memory in the Amazon Basin plays an important role to supply moisture for the La Plata Basin. In the first chapter of this thesis the theoretical basis of this hypothesis and other complementary hypotheses is constructed, based on a literature review. In the second chapter the central hypothesis and other hypotheses are tested with observational data using a new method developed specifically for this purpose. In the third chapter the central hypothesis is tested with experiments of numerical modeling using the Eta/CPTEC regional climate model. Based on the literature review, it was possible to conceptually synthesize the existence of an inter-seasonal and inter-basin hydrological coupling in South America. Using a new methodology development in this thesis, it was possible to prove this hypothesis using observed data, where the hydrological memory of the Southeastern region of the Amazon Basin influences the winter precipitations over the Central-western region of the La Plata Basin. On the other hand, with the numerical modeling experiment increasing the Amazonian tree roots water uptake depth in soils, it is possible to improve the simulation of the moisture convergence and precipitation over the La Plata Basin. The results of this work will be useful to substantiate the public policies of protection of the Amazonian Forest, in terms of the environmental service of water cycling provided by this forest. The results also suggest an important mechanism to improve the coupled climate model parametrizations and its precipitation forecasts over the La Plata Basin.Durante o inverno austral, quando a frequência do Jato de Baixos Níveis a leste dos Andes é maior, a evapotranspiração da porção sul da bacia Amazônica constitui uma importante fonte de umidade para a atmosfera e, consequentemente, contribui com ~ 1/4 das precipitações sobre a bacia do Rio da Prata. Como no inverno austral a porção sul da Amazônia está submetida a um período de reduzidas precipitações, a umidade armazenada previamente no solo profundo durante a estação chuvosa sustenta a evapotranspiração durante a estação relativamente seca. Desta forma, a presente tese de doutorado se baseia na hipótese de que a memória hidrológica Amazônica exerce uma função chave para o fornecimento de umidade para bacia do Rio da Prata. No primeiro capítulo desta tese, é construído o embasamento teórico da referida hipótese, além de outras hipóteses complementares, com base em revisão de literatura. No segundo capítulo, a hipótese central e outras complementares são testadas com dados observados utilizando uma nova metodologia desenvolvida especificamente para este fim. Já no terceiro capítulo, a hipótese central desta tese é testada com experimentos de modelagem numérica utilizando o modelo climático regional Eta/CPTEC. Com base em revisão de literatura, foi possível sintetizar conceitualmente a existência de um acoplamento hidrológico inter-sazonal e inter-bacias na América do Sul. Utilizando a nova metodologia desenvolvida nesta tese, foi possível comprovar a referida hipótese utilizando dados observados, em que a memória hidrológica da região Sudeste da bacia Amazônica influencia as chuvas de inverno na região Centro-oeste da bacia do Rio da Prata. Já nos experimentos de modelagem numérica, aumentando a profundidade de captação de água no solo pelas raízes das árvores Amazônicas, foi possível melhorar a simulação da convergência de umidade e precipitação sobre a bacia do Rio da Prata. Estes resultados são úteis para fundamentar políticas públicas de proteção da floresta Amazônica, devido ao serviço ambiental de ciclagem de água prestado pela floresta. Também sugerem um importante mecanismo para melhorar as parametrizações de modelos climáticos acoplados, e suas previsões de precipitação sobre a bacia do Rio da Prata
Mirmecologia Brasileira no Século XXI: A Coleção do Instituto Nacional de Pesquisas da Amazônia ? INPA.
No full textStocking density for arapaima larviculture
No full textInadequate stock density in fish larviculture can cause a dominant behavior that harms feeding and results in stress, lots of heterogeneous fish and low productive rates. This study aimed to evaluate the effect of stocking densities on growth performance, cortisol levels and arapaima (Arapaima gigas) larvae production cost. Arapaima larvae (1.32 ± 0.25 g; 5.90 ± 0.33 cm) were used and stocked at densities of 400, 800, 1200, 1600 and 2000 larvae m−3. Fish were housed in 15 tanks (50 L) according to a completely randomized design in a recirculating water system with constant aeration. Larvae were fed an extruded commercial diet (45% crude protein) at the 10% biomass proportion, divided into six meals day−1 for 30 days. At the end of the trial, fish were measured and weighed, and four fish per tank were euthanized to analyze plasma cortisol. The arapaima larvae production cost was calculated for all the stocking densities. The fish reared at the 2000 larvae m−3 density presented feeding voracity and the best zootechnical performance: final weight (12.16 ± 0.89 g), weight gain (10.84 ± 0.89 g), relative growth rate (7.69 ± 0.26%) and lower stress levels, which resulted in a 93.33% survival rate. This group of fish presented a low production cost and, consequently, the highest income per larva (2.34 US$). For arapaima larviculture, using 2000 larvae m−3 is recommended because it results in higher growth, more homogeneous fish, better survival rates which, in turn, result in the lowest arapaima larvae production cost. © 202
Primer validation of appetite-regulating and metabolism of peptides in the brain of tambaqui (Colossoma macropomum).
No full textParasitism by Clinostomum marginatum (Clinostomidae) in neotropical electric fish (Gymnotiformes) in the Brazilian Amazon
No full textGymnotiformes are currently recognized as electric fish, the vast majority of which emit low power electrical discharges. Clinostomum trematodes have been the subject of numerous investigations in several host species due to the ability of metacercariae of this genus to infect the muscles, fins and internal organs of fish. The present study aimed to record, for the first time, the occurrence of parasitism by Clinostomum marginatum in Gymnotiformes from the natural environments of two tributaries of the Amazon River in the Brazilian Amazon. Two specimens of Gymnotus coropinae, ten specimens of Brachyhypopomus brevirostris, two specimens of Gymnorhamphycthys petiti and one specimen of Microsternarchus bilineatus were captured. Infection with C. marginatum was identified in the form of 12 encysted metacercariae in the epidermis, with a prevalence of 0.1%, a mean infection intensity of 12/fish and an average abundance of 1.2. This is the first record of parasitism by the C. marginatum in South American Gymnotiformes of the B. brevirostris species
Uncovering a hidden diversity: A new species of freshwater shrimp Macrobrachium (Decapoda: Caridea: Palaemonidae) from Neotropical region (Brazil) revealed by morphological review and mitochondrial genes analyses
No full textA freshwater palaemonid shrimp from the São Francisco river basin in Brazil has been found to be a new species and is herein nominated as Macrobrachium veredensis sp. nov. It is morphologically similar to M. brasiliense (Heller, 1862), which is found in many rivers of South America. However, M. veredensis sp. nov. has a smooth carapace and few spinules on the second pereopods, while M. brasiliense has the anterolateral surface of the carapace with small spinules and the palm of the second pereopods with spines, spinules and setae. Despite their similar morphology with these subtle differences, the remarkable genetic different evidenced in DNA analysis. Molecular analyses were based on 43 sequences with 528 base pairs (bp) for 16S rDNA, and 16 new sequences with 581bp, without pseudogenes, for COI mtDNA. The nucleotide divergence between M. veredensis sp. nov. and M. brasiliense (7.0–8.5% for 16S and 11.8–12.5% for COI.), the phylogenetic topology and the haplotype network configuration and it is endemism to a region of the São Francisco river basin support the recognition of a new taxon. Copyright © 2020 Magnolia Pres
River damming affects seedling communities of a floodplain forest in the Central Amazon
Full text linkThe flood pulse of black water rivers in the Amazon basin determines the composition of species along the flood gradient in igapó forests. The Balbina dam, built on the Uatumã River, has altered the flood pulse and caused changes in the floristic composition of adult trees throughout the downstream area. There is a lack of studies on how communities of seedlings in igapó forests respond to changes in the flood pulse. This study investigates the response of seedling communities in the igapó forest downstream the Balbina dam and compares it with two pristine areas. The areas were sampled with transects of 1x25 m within 36 plots (25x25 m) along the flood gradient. Richness and dominance were calculated by simple regression and ordination analyses. The pristine areas had the same pattern of richness, dominance and genera distribution along the flood gradient. However, the affected Uatumã area formed different groups of genera by NMDS analysis, which divided them along the flood gradient with significantly increased dominance of three genera. The insertion of the Balbina dam resulted a loss of lateral and longitudinal connectivity for the Uatumã River, and the alteration to seedling communities may alter the future landscape of downstream igapó forests
