Distribuição vertical e flutuação sazonal da macrofauna vágil associada a Sargassum cymosum C. Agardh, na praia do Lázaro, Ubatuba, São Paulo, Brasil Depth distribution and seasonal fluctuations of vagile macrofauna associated with Sargassum cymosum C. Agardh at Lázaro beach, Ubatuba, São Paulo, Brazil

<abstract language="eng">Seasonal fluctuations and depth distribution of the vagile macrofauna associated with Sargassum cymosum at Lazaro beach, Ubatuba, São Paulo State, were evaluated through density comparison of higher taxonomic groups among three depth intervals in four periods of the year. Ten groups were identified and among them gammarid and caprellid amphipods were numerically dominant in all sampling periods and did not show any consistent zonation trend. Gastropods, polychaetes and ophiuroids ocurred in lower densities and tended to dominate as depth increased, Wet weight algae variation did not explain the observed spatial and temporal patterns. Biotic interactions, recruitment and environmental parameters are probably involved in seasonal density variation of the faunal groups studied but it was evident that the depth gradient play an important role in vagile macrofauna vertical distribution