Microphytoplankton from coastal waters of Rio de Janeiro: species composition and ecological aspects

Abstract

Phytoplankton of the coastal water between Cabo Frio and Rio de Janeiro were studied at the upwelling season (October, January and Maroh). Qualitative and quantitative variations are analized in function of the hydrological conditions by means of a multivariate statistical treatment of data. Cabo Frio upwelling is responsible for occurrence of a thermocline in the euphotic layer which induces phytoplankton growth, beginning by small-sized species (Nitzschia spp, Skeletonema costatum) and evoluting to highest diversity and quantity of different microphytoplanktonic forms (Guinardia, Rhizosolenia, Chaetoceros, Thalassiothrix). When water column is sharply stratified, we observe Guanabara Bay influence, with high growth of Skeletonema costatum and high quantity of detritus together with blue-green algae and nanoplanktonic forms.