Pinnulariaceae (bacillariophyta) de um lago de inundação amazônico (lago tupé, amazonas, brasil): taxonomia e distribuição espacial e sazonal

Abstract

In order to contribute to the knowledge of diatoms in the river Negro this project aimed at identifying and describing the species of the Pinnulariaceae (Bacillariophyta) family and verifying the possible spatial and seasonal distribution patterns of species richness and composition in lake Tupé, a black water lake of the river Negro river basin. Samples were collected with plankton net (25μm), at three sampling stations from August of 2002 to June of 2004 in scale bimonthly which included the falling and low water periods of 2002 and 2003 and rising water and high water periods of 2003 and 2004. For the morphological analysis of the diatoms the samples were oxidized and the material placed between a slide and cover slip. Three slides from each sample were examined. The Pinnulariaceae community of lake Tupé was made up of 70 taxons belonging to two genera, Caloneis Cleve and Pinnularia Ehrenberg, with three and 67 taxons, respectively. The X2 test showed a significant difference in species richness between sampling stations (X2 0,05(22) = 60,39; p < 0,05) independent of the time of year and significant differences between the high water (June, 2003) and the low water (December, 2003) periods X2 0,05(2) = 6,42; p < 0,05, being that the greatest species richness occurs during the low water period. The Beta diversity was low between sampling stations (ß-1= 22,9) and between the different hydrological periods (ß-1= 37,3) demonstrating more homogenous conditions between the environment and the high degree of change of species between periods. Ten species are cited for the first time for the Brazilian Amazon.