Inter-annual variability of planktonic copepods in a tropical bay in southeastern Brazil

Abstract

The aim of this work was to study the structure of the copepod community in relation to hydrographic conditions in Espírito Santo Bay, from 1993 to 1997. Zooplankton samples were obtained in the horizontal tows four times a year, using a 200 µm net. Temperature, salinity and dissolved oxygen were determined in the water samples. The overall mean density of the copepods was 9,085 ind.m-3 with the peaks exceeding 15,000 ind.m-3 in the summer and autumn during the first three years (1993 - 1995). The PCA analysis was used to relate the environmental conditions with the distribution of the copepods. The increases in the abundant species, namely Acartia lilljeborgi, Oithona hebes, Oithona oculata, Paracalanus quasimodo, Parvocalanus crassirostris and Euterpina acutifrons, were related to the decreases in the diversity. The spatial and temporal variations of the temperature and salinity influenced the abundance of the species during the five years of the sampling and the dominant species alternated in abundance.