Performance de Azolla caroliniana Willd. e Salvinia auriculata Aubl. em efluente de piscicultura

The increasing release of untreated fish farming effluents into water courses that flow to the Pantanal wetlands in Mato Grosso (Brazil) may drive this ecosystem to eutrophication. Therefore, the growth of Azolla caroliniana Willd. and Salvinia auriculata Aubl. in fish farming effluent and their effect on its quality were evaluated for 48 days in a greenhouse. The results were compared to those obtained in a nutrient rich solution (Hoagland 1/2 medium). Azolla caroliniana showed lower relative growth rate in fish farming effluent (0.020 d-1) than in Hoagland 1/2 medium (0.029 d-1). However, S. auriculata grew slightly better in fish farming effluent (0.030 d-1) than in Hoagland 1/2 medium (0.025 d-1). The species apparently contributed to reduce nitrate and phosphate concentration in Hoagland 1/2 medium. However, in fish farming effluent, only electrical conductivity and pH were reduced by plants compared to the control without plants. Thus, A. caroliniana and S. auriculata show low potential for improving effluent quality

Efeito do Uso do Solo Sobre Riachos de Cabeceira na Bacia do Rio Cuiabá, Mato Grosso

The headwaters streams are influenced by the terrestrial environment,which makes them vulnerable to human activities, especially in cerradoareas with intense changes caused by land use. The aim of this studywas to evaluate the effect of land use attributes on headwater streamsin the Rio Cuiabá basin, Mato Grosso. The 26 sampled streams werecharacterized from satellite images and measurements in situ. The attributesmeasured were type of land use in the watershed, dissolved oxygen,pH, temperature, turbidity, riparian width, average width, averagedepth, velocity and substrate type on the channel streams. The turbidityaffected negatively dissolved oxygen in headwater streams, as well asthe channel width positively affected water temperature and the riparianwidth positively affected leaves. Therefore, land use affected directlyand indirectly attributes of headwater streams in Cerrado.Os riachos de cabeceira são influenciados pelo ambiente terrestre, o que os tornam vulneráveis as atividades antrópicas, principalmente em áreas de cerrado com intensa modificação causada pelo uso do solo. O objetivo deste trabalho foi avaliar o efeito do uso do solo sobre atributos de riachos de cabeceira na bacia do Rio Cuiabá, Mato Grosso. Os 26 riachos amostrados foram caracterizados a partir de imagens de satélite e medidas in loco. Os atributos medidos foram tipo de uso de solo na microbacia, oxigênio dissolvido, pH, temperatura, turbidez, largura da mata ciliar, largura média, profundidade média, velocidade média e tipo de substrato no canal dos riachos. A largura da mata ciliar explicou 23,20% do substrato folha no canal dos riachos. A porcentagem de agricultura na microbacia explicou 16,20% da largura do canal. A velocidade média explicou 27,60% da largura do canal. A velocidade média, a largura e a profundidade do canal explicaram 50,10% do substrato silte no canal dos riachos. Portanto, o uso do solo afetou direta e indiretamente atributos de riachos de cabeceira de cerrado

Estrutura e estado de explotação dos estoques do Jurupoca, Hemisorubim platyrhynchos, e do Jurupensém, Sorubim cf. lima, na Bacia do Rio Cuiabá, Pantanla Mato-Grossense.

The fishery is an important economic activity at Pantanal. This study describe and analyse the age, the individual growth, the structure, the exploitation and the management alternatives for the two pimelodidae catfish stocks fished in region. The Porthole Shovelnose Catfish, Ilemisorubim platyrhynchos , and the Duckbill Catfish, Sorubim lima, are, respectively, the sixth and the seventh bigger Pantanal pimelodidae catfish. The fishes were caught by comercial and experimental fisheries with hook and line in Cuiabá river, Pantanal. The age and the individual growth were studied from the (a partir dos) pectoral fin-spines. The estimates fo growth parameters were used to obtain estimate of instantaneous mortality rates for the stocks. The consequences of different managemtn actions for the fishes and the fisheries were assessed with (através) the Beverton and Holt relative yield per recruit model. The results indicate that Il. platyrhynchos and S. lima show slow growth and intermediate natural mortality coeficient. The longevity of Il. platyrhynchos is of 11,4 years, and of S. lima is of 9,6 years. The fisheries catches several fishes cohorts and, in general, individuals abovemean lenght of first maturation. Because historical data are not available it is hard to assess the effects of arising (crescente) fisheries pressure on the stocks. Nevertheless, the results of relative yield per recruit model simulations indicate that presente fisheries effort is below of a conservative biological reference point - the P 0,1. So, the two species stocks are underexploited . However, an arising of presente fisheries effort must be seen with caution because (uma vez que) the raltion between stocks size and recruitment for the two species is not knewFinanciadora de Estudos e ProjetosA pesca é uma importante atividade econômica no Pantanal Mato-grossense. Este estudo descreve e analisa a idade, o crecimento dos indivíduos, a estrutura, o estado de explotação e as opções de manejo para os estoques de duas espécies de bagres pescados na região. O Jurupoca Ilemisorubim platyrhynchos e o Jurupensén Sorubim Lima são, respectivamente, o sexto e o sétimo maiores bagres do Pantanal. Os exemplares provieram da pesca comercial e experimental realizadas com linha e anzol no rio Cuiabá, Pantanal Mato-grossense. A idade e o crescimento dos indivíduos das espécies foram estudados a partir dos espinhos de nadadeiras peitorais. As estimativas dos parâmetros de crescimento foram posteriormente utilizadas na obtenção de estimativas dos coeficientes instântaneos de mortalidade para os estoques. As consequências da adoção de diferentes medidas de manejo para os estoques e a pesca foram avaliadas através do modelo de rendimento relativo por recruta. Os resultados indicam que Il. platyrhynchos e S. lima apresentam crescimento lento e coeficiente de mortalidade natural intermediário. A longevidade do Il. platyrhynchos é de 11,4 anos e a do S. lima de 9,6 anos. A pesca se concentra na captura de várias coortes de peixes, em geral, sobre indivíduos acima do comprimento médio de primeira maturação. A inexistência de dados históricos dificulta qualquer avaliação dos efeitos da crescente pressão de pesca sobre os estoques. Porém, os resultados das simulações do modelo de rendimento relativo por recruta indicam que o esforço de pesca atual está abaixo de um ponto de referência biológico conservador - o P 0,1. Assim pode-se concluir que o estado atual de explotação dos estoques das duas espécies está aquém do que o estoque teoricamente suportaria, portanto subexplotados. Contudo, um aumento no esforço de pesca atual deve ser visto com cautela uma vez que não se conhece a relação entre o tamanho do estoque e o recrutamento para as espécie

High beta diversity of fishes in vegetated littoral zones of floodplain lakes in the Cuiabá River Basin, northern Pantanal, Brazil

This study evaluated whether the alpha and beta diversity of fishes in vegetated littoral zones of floodplain lakes in the Pantanal are randomly distributed on three different spatial scales: within the lake, among lakes, and between regions. Three alternative hypotheses were contrasted: (1) that regional diversity is generated at local scale, depending on the internal environmental heterogeneity of lakes, (2) that the diversity of fishes in floodplain lakes is produced at intermediate spatial scales, depending on structural differences and on the landscape matrix between lakes, and (3) that the diversity of fishes in the littoral zone is generated at regional scale, due to regional differences in land-use pattern and the presence of a geographical barrier represented by the river. Our results indicate that the regional diversity of fishes in the vegetated littoral zone of lakes in the northern Pantanal is a consequence of high diversity at the local level (α) and the wide differences in species composition among lakes and between regions. This suggests that we need to maintain environmental heterogeneity, represented by the structural differences among the lakes and their landscape matrix as well as regional differences in the flood pattern, if we hope to preserve the diversity of fishes in the region. Besides, it is necessary to establish new conservation units at the different Pantanal subregions, which should incorporate a set of lakes with different landscape features such as size, shape, and distance from and degree of connection to rivers. © 2011 Springer Science+Business Media B.V

Size-dependent response of tropical wetland fish communities to changes in vegetation cover and habitat connectivity

Context: The replacement of native vegetation by exotic grasses for livestock production is driving landscape homogenization, habitat fragmentation and reducing connectivity between habitat patches in floodplains ecosystems. Objective: In this context we examined how changes in native and exotic vegetation cover, connectivity and water depth affect the attributes of the small [standard length (SL) < 80 mm as adults] and large-sized fish assemblages (SL ≥ 80 mm as adults). Method: We assessed the effects of water depth, exotic and native vegetation cover and habitat connectivity on the abundance, species richness, body size and biomass of fish assemblages in a 25 km2 area of the seasonal habitats of the Pantanal wetland over 5 years. Results: We showed that fish assemblage response to meso-scale variation in water depth, vegetation cover and habitat connectivity in seasonal habitats is size-dependent. The gradient from exotic to natural vegetation cover did not affect the assemblages of small-sized fish, which were mostly regulated by water depth, habitat connectivity and the gradient from grassland to forest. However, besides being affected by water depth and habitat connectivity, large-sized fish were also affected by the gradient from exotic to natural vegetation cover. Conclusion: Our results indicate that transformations in the landscape and changes in the dynamics of inundation may have negative consequences for the long-term persistence of fish assemblages in the Pantanal wetlands. © 2015, Springer Science+Business Media Dordrecht

Population Structure of Mesoclemmys vanderhaegei (Bour, 1973) (Testudines:Chelidae) in the Cerrado of Chapada dos Guimar\ue3es, Mato Grosso, Brazil

Studies on population structure of freshwater turtles belonging to the family Chelidae are scarce in Brazil. Herein we describe the structure of a population of the chelid Mesoclemmys vanderhaegei in a Cerrado area in the municipality of Chapada dos Guimarães, Mato Grosso, Brazil. A total of 80 individuals were captured in five collecting sites, from January to March 2007: 42 adult females, 27 adult males, and 11 juveniles with undetermined sex. Among 80 individuals, 24% were recaptured, at least once. This is the first attempt to estimate the size of a population of Mesoclemmys vanderhaegei. Our results suggest that additional sampling efforts are needed for more accurate estimates of population structure. Nevertheless, they surely provide minimum values of the number of individuals of M. vanderhaegei living in the locality sampled

Spatiotemporal dynamics in a seasonal metacommunity structure is predictable: The case of floodplain-fish communities

The metacommunity framework has greatly advanced our understanding about the importance of local and regional processes structuring ecological communities. However, information on how metacommunity structure and the relative strengths of their underlying mechanisms change through time is largely lacking. Dynamic systems that undergo environmental temporal changes and disturbances, such as floodplains, serve as natural laboratories to explore how their metacommunity structure change in time. Here we applied the Elements of Metacommunity Structure framework and variation partitioning analysis to assess how temporal changes in the local environmental factors and regional dispersal processes in the rain season influence a seasonal floodplain-fish metacommunity. Across four months, relevant environmental factors were measured across 21 patches where over 3500 individual fish were sampled. Connectivity was measured using landscape resistance-based metrics and additional spatial variation in metacommunity structure was assessed via spatial autocorrelation functions. The metacommunity structure changed from nestedness, at the beginning of the flood season, to a quasi-Clementsian gradient at the end. Our analyses show that connectivity is only important in the beginning of the flood season whereas environment is only important at the end. These results suggest that this metacommunity is structured by changes between dispersal limitation and environmental filtering through time. © 2013 The Authors