Comunidade fitoplanctônica do reservatório Padre Cícero (Castanhão), Ceará

Abstract

Water reservoirs play a fundamental role in the Northeast Brazil acting toward a reduction of the impacts caused by the periodical draughts of the region. Multiple uses of these reservoirs make more difficult their management and intensifies the degree of interference and instability of their aquatic biota. Present study aimed at characterizing the phytoplankton community of the Public Reservoir “Padre Cícero” (locally known as Castanhão), located in the Municipality of Jaguaribara, Ceará State, whose operational capacity is 4.45 billion cubic feet. Samples were gathered from 69 localities during months February and August 2012 and March and August 2013. The study reavealed the occurrence of 44 taxa among species and taxonomical varieties, which were distributed in five classes, 19 orders, 24 families, 37 genera and 36 species. Representative specimens of Cyanobacteria presented their greatest representativeness (13 species) in 2013, chiefly during the dry period of the year. Specimens of Chlorophyceae presented their greatest representativeness (14 species) in 2013, however, during the rainy season. Genera occurring with greatest frequency along the two periods of present study were: Pseudanabaena, Botryococcus, Oocystis, Staurastrum, Aulacoseira, Fragilaria, Gomphonema and Ulnaria. Present investigation pointed for the need of a systematic and persevering evaluation of the phytoplankton of the reservoir, mainly of the Cyanobacteria due to the persistent incidence of antropogenic activities in the reservoir and above all the use of “fishcage” that threatens the ecological quality of the reservoir water in a region that deals since long time ago with the problem of water scarcity, a characteristic of the Brazilian Northeast.