Alto Pantanal地区的汞含量:一个透视研究

采用附加有氢化物发生器的原子吸收光谱仪,测定了巴拉圭河上游流域内9个点的土壤、沉积物、鱼和鸟类羽毛中的汞含量。采金所大量使用的汞会直接散发至空气中或被河流运至Pantanal地区。Pantanal地区的生态系统不仅对在当地生活、捕鱼和饲养牲畜的人们来说很重要,而且对远方城市的居民也很重要,因为城市居民所吃的鱼来自这一地区。他们还可从这一地区的旅游业中得到许多经济实惠等。当地重要的商品是鲇鱼(Pseudo-platystoma coruscans),但其中的汞含量已超过可食用的上限值(0.5ppm湿重),且远远超过自然本底值。鸟类羽毛中的汞含量也表明了这种生物富集作用。土壤和沉积物中的汞积累未达到统计学上的显著水平。汞齐化过程排放的汞比土壤矿物中固有的汞更易被生物所利用。采金过程中的汞回收技术并没有阻止汞的扩散。限制国际范围内的汞交易可能会显著减少汞的污染。

New patterns of the tree beta diversity and its determinants in the largest savanna and wetland biomes of South America

Clear and data-driven bioregionalizations can provide a framework to test hypotheses and base biodiversity conservation.Here we used occurrence and abundance data in combination with objective analytical methods to propose two bioregionalization schemes for tree species of the Cerrado and the Pantanal in South America.We also evaluated the contribution of three sets of determinants of the occurrence-and abundance-based subregions.We compiled data on tree species composition from 894 local assemblages based on species occurrences,and from 658 local assemblages based on species abundances.We used an unconstrained community-level modelling approach and clustering techniques to identify and map tree subregions for the occurrence and the abundance data sets,separately.Hierarchical clustering analyses were conducted to investigate floristic affinities between the subregions and to map broader floristic regions.We used multinomial logistic regression models,deviance partitioning,and rank-sum tests to assess the main subregion correlates.We identified 18 occurrence-and four abundance-based subregions in the Cerrado-Pantanal.The hierarchical classifications grouped the occurrence-based subregions into nine floristic zones and abundance-based subregions into two broad floristic zones.Variation in subregions were explained mainly by environmental factors and spatial structure in both occurrence and abundance data sets.The occurrence-and abundance-based subregions are complementary approaches to disentangle macroecological patterns and to plan conservation efforts in the Cerrado and the Pantanal.Our findings based on occurrence data revealed more complex and interdigitated boundaries between subregions of tree species than previously reported.The environment,historical stability,and human effects act in a synergetic way on the distribution of the subregions.Finally,the relevance of contemporary environmental factors to the subregion patterns we found alert us to the profound impact global warming may have on the spatial organization of the Cerrado-Pantanal tree flora.

Cytogenetic Analysis of Three Species of Astyanax Genus （Pisces, Characidae, Incertae sedis） from Freshwaters of Upper Paraguay Basin, Mato Grosso State, Brazil

Cytogenetic studies have shown that the genus Astyanax has extensive karyotypic variability among species and many are the works developed about this group in different river basins in Brazil. The Tangara da Serra area （Mato Grosso State, Brazil）, which contains tributaries of both Amazon and Upper Paraguay River basins is, therefore, a natural watershed. Thus, in this work, the karyotypes of three species of Astyanax from the Sepotuba River＇s tributary streams were analyzed by using conventional methods of chromosome analysis. Astyanax marionae presented 2n =48（12m＋ 10sm＋ 12st＋ 14a） and NF （fundamental number） = 82 with evident heterochromatin in several chromosomal regions. Astyanax cf. asuncionensis presented 2 n = 50 （20m ＋ 12sm ＋ 6st ＋ 12a）, NF = 94 chromosomes and with evident heterochromatin in few chromosomes and Ag-NOR in one chromosome pair. Astyanax cp. scabripinnis presented 2 n = 50 （12m ＋ 10sm ＋ 10st ＋ 18a）, NF = 82 with evident heterochromatin at most of the chromosomes in pericentromeric region and a strongly marked block on a telocentric chromosome pair. The Ag-NORs were observed near the heterochromatic region. The karyotypic differences found, probably occurred by chromosomal rearrangements, resulting in a heterogeneous model of chromosomal evolution who probably involved both Robertsonian chromosomal rearrangements to A. marionae, as not Robertsonian to other Astyanax species. This indicates that although these species share the same hydrographic basin （Upper Paraguay） are isolated in different microbasins and the absence in the gene flow may have allowed the establishment of independent rearrangements in each population.

Morphometric Characterization of a Watershed through SRTM Data and Geoprocessing Technique

The aim of this study is to characterize the morphometry of a watershed using radar data Shuttle Radar Topographic Mission (SRTM) and GIS techniques. The study is conducted in the watershed of the Indaiá stream, which is located in the southwestern region of the municipality of Aquidauana, MS, Brazil and has an area of 94.6764 km2. A tributary of the Taboco River consequently enters the Pantanal lowlands. Classical morphometric parameters were calculated and specialized through spatial analysis in geographic information systems. The main results of the morphometric characterization were the variables of form factor, drainage density, coefficient of compactness, and maintenance coefficient, as well as the relief parameters found, including the hypsometry, slope, aspect and relief dissection (horizontal and vertical amplitude). The integrated analysis of the variables (morphometric and relief) concludes that the watershed has low susceptibility to flooding but that the morphology of the relief and lithological structure favors the development of erosion processes in the watershed.

Fire dynamics in Mato Grosso State,Brazil:the relative roles of gross primary productivity

The fires and biomass burning are responsible for affect ecosystem processes in a wide range of biomes at regional and global scales.In Brazil,the state of Mato Grosso is one of the most affected by the occurrence of forest fires.Thus,this study aims to quantify the longterm changes in the temporal and spatial patterns of fire occurrence and their effect on gross primary productivity(GPP)in the state of Mato Grosso,Brazil,considering the biomes that compose it.The images used in the study were acquired by satellite Terra and Aqua combined in the product MCD64A1.006,a monthly resolution of 500m by the Moderate Resolution Imaging Spectroradiometer(MODIS)sensor,during the period from 01/10/2000 to 12/31/2018.The MOD17A2 product derived from the MODIS sensor provides the accumulated value of GPP.The points without the presence of burning presented higher values of GPP for all studied biomes.In some points with the presence of burning the GPP even decreased by 44.20%,30.04%and 55.78%for Amazonia,Cerrado,and Pantanal,respectively.According to the results presented here,it is concluded that the burnings negatively impact gross primary production in the biomes of the state of Mato Grosso,Brazil and the dynamics of the burns do not keep up with the intensity of drought years.The use of cluster analysis techniques,such as principal component analysis(PCA),is an alternative to bigdata analysis when the objective is to evaluate the presence of forest burning in more than one biome.

Abiotic drivers shape seed inputs and outputs in a tropical wetland on Croton trinitatis population

Background:Predicting how natural and anthropogenic drivers shape different ecological indicators,such as plant populations along environmental gradients,can be a relevant tool for establishing management and conservation criteria of tropical wetlands.We aimed to assess the effects of seasonal flood disturbance,type of grasslands and topographical conditions on Croton trinitatis population distribution in a tropical wetland.Methods:The study was carried out in a seasonally flooded grassland(Central-West Brazil).We conducted samplings of soil on the dry and flood hydrophases of the Pantanal.We took the samples in eight seasonal ponds,with 1 km interval between them.Transects were marked during the flood period,observing the water level,one in the lowest zone,in the middle of the pond=low(ca.60 cm deep),one at the pond edge=mid(ca.30 cm deep)and one in the higher zone,on the external part=high(ca.1 cm deep).Results:The results showed that the topography,seasonality,and types of grassland determine differences in the abundance patterns of adult plants and seedlings,and seed bank and seed predation.The abiotic factors can shape plant population-related ecological processes and patterns,with outputs(germination and predation)and inputs(local dispersion and from neighbouring areas)of proportional seeds for the population maintenance in this environment.Conclusion:We emphasize the importance of these findings,to show that abiotic factors are not the only ones to be considered in ecological studies of distribution and structuring of populations in habitats with extreme seasonal events.

Differences between species in seed bank and vegetation helps to hold functional diversity in a floodable Neotropical savanna

Aims Our objective was to quantify the contributions of the seed bank and the established vegetation to the species composition,functional composition and diversity,and discuss the implications of these differences in regeneration and persistence of floodplain plant communities.Methods We sampled all ground cover vegetation up to 1.5 m height and seed bank in 25 plots(10 m×1 m)distributed across five sites in dry and rainy seasons in a periodically flooded savanna in the Pantanal wetland,Brazil.We evaluated the soil seed bank by seedling emergence method.Important Findings The seed bank species had traits that conferred regeneration to the communities,while persistence traits characterized the vegetation.The seed bank had higher functional richness and lower functional evenness than the vegetation.The existence of different plant traits between seed bank and vegetation allowed the coexistence of species with functionally contrasting persistence and regeneration traits,which may help maintain functional diversity.It may allow the community to be more resilient when dealing with different environmental filters such as drought,fire and flood.