The periodicity of the hydrological cycle in floodplains influences (in a positive manner) the aquatic productivity and ecological processes, as a result of changes in the areas along floodplains. The production of biomass and the cycling of nutrients occurs mainly in the lake area of floodplains. Floodplains of tropical rivers differ from the river continuum where communities along the river are distributed so as to harmonize with their feeding habitats to utilize the transported material. Palavras chave: Planície de inundação, fase de águas altas, fase de águas baixas, comunidade de Rotifera.įor tropical rivers with broad floodplains areas, the flood pulse is a key factor that initiates and controls the the productivity of the energy flow of these systems. Key words: Floodplain, high water phase, low water phase, Rotifera community. Avenida André Araújo, 69060-001 Manaus, Amazonas, Brasil E-mail: de Zooplancton, Instituto Nacional de Pesquisas da Amazônia. Rodovia Carlos Tonanni, 14870-000 Jaboticabal, São Paulo. IPrograma de Pós-Graduação em Aqüicultura, Centro de Aqüicultura, Universidade Estadual Paulista. Planície de inundação fase de águas altas fase de águas baixas comunidade de RotiferaĪbundance and composition of Rotifera in an abandoned meander lake (Lago Amapá) in Rio Branco, Acre, BrazilĪbundance and composition of Rotifera in an abandoned meander lake (Lago Amapá) in Rio Branco, Acre, Amazonia, BrazilĮrlei Cassiano Keppeler I Elsa Rodrigues Hardy II Mudanças sazonais, causadas pelas flutuações do nível da água, e baixa diversificação dos nichos influenciaram a composição e abundância do grupo estudado. As análises de correlações de Pearson revelaram que a condutividade elétrica foi negativamente correlacionada com a densidade de rotíferos (r = -0,8824 p < 0,05), na fase de águas baixas, bem como, profundidade, na fase de águas altas (r = -0,7513 p < 0,05). Transparência e pH foram estatisticamente altamente significativos (p < 0,01). Anova e teste F foram usados, visando observar diferenças sazonais nas variáveis ambientais e rotíferos. A diversidade e abundância foram caracterizadas por serem maiores, respectivamente, nas águas altas e águas baixas. A densidade e composição de rotíferos (48 táxons de rotíferos) foram determinadas. As amostragens foram realizadas semanalmente em três estações de coletas, em dois períodos: estação seca entre 08/V/1997 e 31/X/1997 e estação chuvosa, entre 02/I/1998 e 24/II/1998. Seasonal changes, caused by an increase in water levels and the low diversification of niches, influenced the composition and abundance of the animal group studied.įloodplain high water phase low water phase Rotifera communityĪ comunidade de rotíferos do Lago Amapá (meandro abandonado da planície de inundação do Rio Acre) foi investigada sazonalmente. Pearson's correlation was used to show that rotifer numbers during the low-water phase correlated negatively with electrical conductivity (r = -0.8824, p < 0.05) and during the high-water phase correlated negatively with depth (r = -0.7513, p < 0.05). Anova was performed, by means of the F test, to test for seasonal differences in environmental variables and rotifers, showing that there was a highly statistically significant difference for pH and transparency (p < 0.01). The density and composition of rotifer species (48 taxons of rotifers) were determined, and their diversity and abundance were observed to be greater, respectively, at high-water and low-water. Sampling was performed at three collection stations, generally weekly, during the dry season between and October 31, 1997, and during the rainy season between Januand February 24, 1998. The rotifer community in Lago Amapá (abandoned meander lake of the Rio Acre floodplain) was investigated with respect to seasonal changes.
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