Associações de espécies de peixes em ambientes lóticos da bacia do rio Iguatemi, Estado do Mato Grosso do Sul

The aim of this paper is to describe the patterns of associations between fish species and their distribution in lotic habitats at basin level. Samples were accomplished in 27 localities of Iguatemi river basin, distributed in four environments (Iguatemi river, Jogui river, Puitã river and streams). The presence/absence data of those species which occurred in 2 or more sites were submitted at multivariate methods with the aim to describe the major species associations. The species distribution was considered determinative in these communities (C-score = 17,33; P = 0,000), with significant difference among the studied environments (ANOSIM r = 0,082; P = 0,012), with verified difference between Iguatemi river and streams (P = 0,001) and also streams and Jogui river (P = 0,014). We verified a strong segregation among species from headstreams and more discharge river stretches or even larger streams.

Late Pleistocene and Holocene paleoenvironments in ponds and alluvial sediments of Upper Paraná River, Brazil

Freshwater sponge spicules were analyzed as a paleoenvironmental proxy indicator in five cores of ponds and alluvial fan sediments in the Upper Paraná River's left bank, near Querência do Norte town, northwestern of State of Paraná, southern Brazil. Two optically stimulated luminescence (OSL) dates were obtained from sediments of ponds and one radiocarbon (14C) date was obtained from the alluvial fan. Microscopic analysis of spicules preserved in the sediments allowed a determination of freshwater sponge species. The species assemblage provides evidence for dominantly dry conditions in the Upper Paraná River during the Late Pleistocene. A wetter climate phase was recognized at 14C 7,540 yrs BP, with alluvial fan formation commencing at the transition of the dry Pleistocene climate to the Early Holocene wet climate. This wet interval was characterized by a sponge assemblage marked by the presence of the Neotropical families and typically associated with lotic environments. Sponge spicules analysis from pond sediments reject the possibility that lotic environments contributed to pond genesis and evolution. © 2013 by the Sociedade Brasileira de Paleontologia.

Distribuição ecológica das comunidades de macroalgas de ambientes lóticos em duas unidades de conservação abrangendo os biomas da Floresta Estacional Semidecidual e Campos no estado do Paraná

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Macroalgas lóticas do Parque Nacional Chapada dos Veadeiros e arredores (GO): levantamento florístico e distribuição ecológica das comunidades

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Características fotossintéticas de produtores primários de ambientes lóticos

Pós-graduação em Ciências Biológicas (Biologia Vegetal) - IBRC

Taxonomia, distribuição ambiental e considerações biogeográficas de algas verdes macroscópicas em ambientes lóticos de unidades de conservação do sul do Brasil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estradas, alagados antrópicos, peixes e a fragmentação de redes fluviais em uma paisagem agrícola do Nordeste do Pará

Estradas cruzando riachos (ou igarapés) por estruturas mal planejadas podem ocasionar alagamentos em segmentos do canal à montante do cruzamento, transformando este trecho de um ambiente lótico em um lêntico. O presente trabalho teve como objetivo estudar a diversidade e a estrutura trófica funcional de comunidades de peixes em alagados de origem antrópica na região nordeste do Pará. Estes alagados são formados pelo cruzamento de estradas sobre a rede fluvial, com maiores ou menores impactos sobre sua conectividade hidrológica, assunto que é largamente ignorado em sistemas lóticos neotropicais. Foram amostrados dezoito trechos de canais em sete igarapés nas bacias dos rios Maracanã e Marapanim, sendo seis deles cruzados por estradas, e um não, como referência. Todos igarapés estão localizados na região nordeste do estado do Pará, sendo cinco nos municípios de Igarapé-Açu e Marapanim, inseridos em uma paisagem agrícola, e dois no município de São Francisco do Pará, inseridos em uma matriz florestal. Dos seis igarapés cruzados por estradas, cinco apresentaram a formação de amplas áreas alagadas. Nestes locais, foram selecionados três trechos do sistema fluvial para amostragem de peixes: um à montante do alagamento, um no próprio alagamento e outro à jusante. No igarapé que não apresentava alagamento, selecionou-se, apenas dois trechos: montante e jusante do cruzamento da estrada sobre o canal. Os ambientes selecionados foram amostrados uma vez, entre junho e novembro de 2010, por técnicas de censo visual, em segmentos de 200 metros de extensão. Foram registradas 73 espécies distribuídas em seis ordens, 26 famílias e 63 gêneros. Characiformes (38,4%) e Siluriformes (31,5%) foram as ordens mais representativas em números de espécies. Characidae, com 15 espécies (20,5%), e Cichlidae, com 10 (13,7%) foram as famílias mais representativas em número de espécies. Estas espécies foram organizadas em 18 grupos tróficos funcionais (GTF), formados de acordo com a tática alimentar observada com maior frequência para cada espécie e sua distribuição espacial observada durante as sessões de mergulho ad libitum. Os alagamentos impuseram modificações na estrutura biótica e física dos igarapés. Estes ambientes apresentaram menor número de espécies, maior abundância e menor diversidade de espécies e de GTF em relação aos trechos à jusante e à montante. Os alagamentos apresentaram maior largura, profundidade e temperatura; e menor velocidade e oxigênio de dissolvido quando comparados aos trechos de igarapés à montante e à jusante. O uso da abordagem de grupos tróficos funcionais facilitou na inferência de como o processo de fragmentação da rede fluvial interfere na estrutura da assembleia de peixes estudada.

A similaridade no uso do microhabitat por girinos (Amphibia, Anura) reflete processos ecológicos ou filogenéticos?

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Short-term effects of visitor trampling on macroinvertebrates in karst streams in an ecotourism region

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Description of the larva of Kempnyia colossica (Navas) (Plecoptera: Perlidae) with biological notes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Assembleias fitoplanctônicas no gradiente longitudinal barragem-jusante do reservatório de Itaipu, rio Paraná (Brasil/Paraguai)

The freshwater phytoplankton, responsible for a significant part of primary production in rivers and lakes, is of great importance for matter and energy available to other trophic levels of structuring aquatic food chains. In recent decades, the construction of dams, especially for the generation of electricity, produced changes not only in physical and chemical characteristics of rivers, but also in biocoenosis of these ecosystems. Thus, research is needed to expand the basic knowledge about these environments and subsidize actions appropriate conservation and management. Considering that lotic environments are relatively little studied, and the river-reservoir interaction, the work aims to analyze the limnological conditions and assemblies phytoplankton along the gradient established by the Itaipu reservoir and downstream stretch of the Paraná River. During two periods of the year, winter and summer, we analyzed nine sampling stations: one in lentic environment (the dam), six on the Parana River (each 5 km), at the mouth of a river Monday and another at the mouth of the Iguazu river. The phytoplankton community was composed of 315 taxa, with the class Bacillariophyceae most specious. At every point the richness was higher in summer and with a longitudinal trend in the increasing points after falling after the dam and the contribution of the tributaries. The number of taxa common to the three rivers was low in both study periods. The higher taxa can be explained by the variety of environments sampled, different residence times of water and nutrient concentrations, whereas the rivers Iguazu and Monday suffer high human influence. The greater abundance of organisms in the dam, in both periods, it should be the class Cryptophyceae contributing over 75% of total phytoplankton in point. In cluster analysis (composition and abundance)...(Complete abstract click electronic access below)

Estudo da viabilidade de sedimentos formulados para a aplicação em estudos ecotoxicológicos e químicos: ênfase para os interferentes endócrinos 17alfa-etinilestradiol e 17beta-estradiol

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Evolução geomorfológica e palaeoambiental dos terraços da margem esquerda do alto rio Paraná

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Allometric growth of two species of Ephemeroptera from Neotropical mountains streams

The present study evaluated the relative growth and allometry of Massartella brieni Lestage and Thraulodes sp. (Leptophlebiidae: Ephemeroptera). The morphometric analysis was based on 23 measurements and was conducted using a multivariate approach. Throughout postembryonic ontogeny, all of the head measurements, including those of the mouthparts, exhibited negative allometric growth. The mesothorax and wing pad exhibited positive allometric growth. The hind legs lengths in M. brieni and the fore and hind legs lengths in Thraulodes sp. exhibited positive allometry. The abdominal length in these two species exhibited positive allometric growth. Positive allometry was also observed along the abdomen width for M. brieni, and isometry was observed for Thraulodes sp. The relative strengthening of the thorax (in preparation for the winged stage) and the relative increase in the abdomen (which may be related to the development of the reproductive structures) during growth indicate that many of the structures that exhibit positive allometric growth are related to the transition from the aquatic to the adult stage of development.

Finite Element Modeling of Shell Shape in the Freshwater Turtle Pseudemys concinna Reveals a Trade-Off between Mechanical Strength and Hydrodynamic Efficiency

Aquatic species can experience different selective pressures on morphology in different flow regimes. Species inhabiting lotic regimes often adapt to these conditions by evolving low-drag (i.e., streamlined) morphologies that reduce the likelihood of dislodgment or displacement. However, hydrodynamic factors are not the only selective pressures influencing organismal morphology and shapes well suited to flow conditions may compromise performance in other roles. We investigated the possibility of morphological trade-offs in the turtle Pseudemys concinna. Individuals living in lotic environments have flatter, more streamlined shells than those living in lentic environments; however, this flatter shape may also make the shells less capable of resisting predator-induced loads. We tested the idea that ‘‘lotic’’ shell shapes are weaker than ‘‘lentic’’ shell shapes, concomitantly examining effects of sex. Geometric morphometric data were used to transform an existing finite element shell model into a series of models corresponding to the shapes of individual turtles. Models were assigned identical material properties and loaded under identical conditions, and the stresses produced by a series of eight loads were extracted to describe the strength of the shells. ‘‘Lotic’’ shell shapes produced significantly higher stresses than ‘‘lentic’’ shell shapes, indicating that the former is weaker than the latter. Females had significantly stronger shell shapes than males, although these differences were less consistent than differences between flow regimes. We conclude that, despite the potential for many-to-one mapping of shell shape onto strength, P. concinna experiences a trade-off in shell shape between hydrodynamic and mechanical performance. This trade-off may be evident in many other turtle species or any other aquatic species that also depend on a shell for defense. However, evolution of body size may provide an avenue of escape from this trade-off in some cases, as changes in size can drastically affect mechanical performance while having little effect on hydrodynamic performance.