DINÂMICA DIURNA E SAZONAL DO FITOPLÂNCTON DO ESTUÁRIO DO RIO PARAÍBA DO NORTE - ESTADO DA PARAÍBA - NORDESTE DO BRASIL

Abstract

In order to study the dunal and seasonal dynamics of the phytoplankton in the estuary of the Paraiba do Norte River, water collections for cell countings were made every two hours and monthly, from October 1989 to September 1990. Large diurnal changes were always observed and maximum values surpassed the minima between 1.5 and 3.1 times. The annual cycle showed higher cells densities after the rainfall period. No relation was observed between total phytoplanktonic concentrations and the tidal rhythms, although the fractions of ≥5 <10 µm and ≥ 20 µm showed a good synchronism with the incoming and high tides and with the low tidal condition, respectively. The monads, the phytoflagellates and the ediatoms Thalassiosira spp of the ≥5 < 10 µm and < 5 µm size fractions, dominated throughout the seasonal cycle. Substitutions of the dominant organisms were frequent, particularly in the higher size fractions.