The qualitative structure as well as the distribution of Paracalanidae species off São Sebastião region, São Paulo State, Brazil, were studied from samples taken during Summer 1994 at 43 stations. Seven species belonging to the genera Paracalanus and Acrocalanus were identified: Paracalanus quasimodo, Paracalanus indicus, Paracalanus aculeatus, Paracalanus campaneri, Paracalanus crassirostris, Paracalanus nanus and Acrocalanus longicornis. The three first species were the most frequent and abundant in the area. The populations of Paracalanidae were composed basically of adult females, males and copedids IV -V and their densities were higher in the region localized between 20 m and 74 m. depth. The vertical distribution also was studied for a 24-h period at a fixed station (46 m. depth). High densities of Paracalanidae were found mostly above the thermocline specially during the nocturnal period, indicating a nocturnal upward migration.
Copepod distribution; Paracalanidae; Population density; South Atlantic; São Sebastião: SP; Brazil