Diversity of freshwater algae

Abstract

ln this paper we present an historical review of the published information on freshwater algae collected within the Mondego Basin and report on the algae identified in a survey covering the Basin area. The reviewed publications concem predominantly taxonomy and go back to the beginnings of the 19th century. ln the last thirty years, the possibility of combining taxonomic and ultrastructural studies led to the establishment of a culture collection of microalgae at the Department of Botany. University of Coimbra (ACOI). Only a few ecological studies have been conducted in the area, quite recently. conceming the structure and dynamics of the phytoplankton. A survey of the phytoplankton composition in 21 sites located from the highland areas to the coast revealed the presence of 388 taxa. the great majority being diatoms (232 taxa). Green algae, euglenophytes and silica-scaled chrysophytes were other well represented groups, with 60,48 and 35 taxa. respectively. The remaining algal groups were poorly expressed by this survey. Higher algal variety was found in the eutrofic waters of the lowland rice-field areas of the Basin when compared with the oligotrophic waters of Serra da Estrela However; a remarkable flora develops in the small ponds of this area in spring. due to the occurrence of rare specimens of chrysophytes and desmids. Introduction