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Registros recuperados: 5
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Adaptation of constant effort sampling and of removal trapping for the estimation of populations of microscopic organisms in dense substrates () Acta Amazonica
Walker,Ilse; Lages,Maryolanda Trindade.
Abstract Large numbers of thecamoebae are found in the sand and detritus substrate of small streams in the Amazonian terra firme forest. Their relative population densities can be determined by searching and counting thecae under a dissecting microscope for a standard time interval (constant effort sampling). The total population per sample can be calculated from a gradual linear depletion during successive such counts in a given sample (removal trapping). From a series of such regressions the total number of thecamoebae of any sample can be estimated from a single, first count. The method depends on specific conditions with regard to size of area searched, quantity of substrate per area, density of organisms per substrate and performance of the observers....
Ano: 1980 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59671980000300535
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Omnivory and resource - sharing in nutrient - deficient Rio Negro waters: stabilization of biodiversity? Acta Amazonica
Walker,Ilse.
Amazonian biodiversity is notorious, this is also valid for the fauna of the mineral-deficient waters of the Rio Negro System. Some 25 years of research on the benthic fauna of Central Amazonian streams resulted in species-rich foodwebs with a high degree of omnivory within dense animal communities. To exemplify the taxonomic range of omnivorous consumers, the detailed resource spectra of 18 consumer species, including Protozoa (2 species), Platyhelminthes (1 species), insects (2 species), fish (6 species) and shrimps (Decapoda, 7 species), associated primarily with the benthic habitats of Rio Negro tributaries, are presented. Special features of omnivory are characterized, and the importance of litter-decomposing fungi as essential energy input into the...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Amazonas; Rio Negro; Omnivory.
Ano: 2009 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59672009000300017
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Rede de alimentação de invertebrados das águas pretas do sistema rio Negro 1. Observações sobre a predação de urna Ameba do tipo Ameba discoides. Acta Amazonica
Walker,Ilse.
Resumo Observação de pequenos ecossistemas estabelecidos quase naturalmente no laboratório a partir de material coletado em "habitats" específicos do rio, permitiu construir uma rede alimentar da Amoeba (discoides), um predador voraz proveniente da fauna encontrada entre capins submersos nas margens de lagos e rios. O comportamento predador é bastante variado; as presas preferidas são ciliados, e, além de vários outros protozoários, a ameba ataca anelídeos (Aeolosoma sp.). Observou-se a caça cooperativa a espécies presas que chegam a fugir se atacadas por amebas solitárias. Cooperação é definida em termos de aumento de alimento obtido. Todos os organismos predadores na rede mostravam-se específicos na escolha da presa, notando-se também preferências por...
Tipo: Info:eu-repo/semantics/article
Ano: 1978 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59671978000300423
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The food spectrum of the cardinal - tetra (Paracheirodon axelrodi, Characidae) in its natural habitat Acta Amazonica
Walker,Ilse.
The cardinal tetra (Paracheirodon axelrodi) is the most intensively commercialized ornamental fish from the Rio Negro Basin (Amazonas State, Brasil). Analysis of the stomach and gut contents of fish caught in their natural habitats show conclusively that the cardinal is essentially a predator, feeding on the mesofauna that adheres to submerged litter, roots and waterplants. Microcrustacea and chironomid larvae (Diptera) were the most frequently ingested prey, while algae intake was relatively infrequent. It is argued that the relatively small size of the cardinals captured in their natural habitat is due to the annual migrations imposed by the inundation cycles, rather than to resource limitation, because it is known from earlier investigations of similar...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Rio Negro; Cardinal; Diet.
Ano: 2004 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59672004000100009
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The thecamoebae (Protozoa, Rhizopoda) of small Amazonian forest streams and their possible use as indicator organisms for waterquality Acta Amazonica
Walker,Ilse.
Abstract The thecaboemae fauna of seven central amazonian forest streams — among them the stream of the "Bacia Modelo" — was analised. 129 morphotypes are shortly characterized in a "list of morphotypes" with accompanying figures (Plates 1-7); 39 morphotypes were observed alive and food uptake determined in 20 of these. Their food consists primarily of spores and hyphae of fungi which decompose submerged leaf litter and detritus. Analysis of sequential samples suggests that most species were found in each stream, but that collection in further streams is expected to increase the total number of morphotypes considerably. Frequency and distribution of morphotypes, as well as total population density, are characteristic for each stream and seem to reflect...
Tipo: Info:eu-repo/semantics/article
Ano: 1982 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59671982000600079
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