This work verified the daily zonation of benthic macrofauna in Tramandaí, Harmonia and Jardim do Éden beaches, north coast of the state of Rio Grande do Sul, southern Brazil, for five consecutive days. Biological data were collected with a PVC core (20 cm diameter) along three transects distant 50 m of each other, with four levels and three samples in each level. First level was always positioned 8 m above the superior limit of swash zone and the last one was 1 m depth. There was also daily data collection of beach topographical profiles. Benthic macrofauna organisms showed a regular pattern of zonation along all days, with intertidal zone marked by the presence of the isopod Excirolana armata (Dana, 1853) and the polychaeta Euzonus furciferus (Ehlers, 1897). Swash zone was represented by a high abundance of the hippid crab Emerita brasiliensis (Schmitt, 1935), the pelecypod Donax hanleyanus (Philippi, 1842) and the polychaeta Scolelepsis gaucha (Orensanz & Gianuca, 1974). Surf zone and breaker zone did not show differences in species composition, being dominated by juvenile D. hanleyanus, Mesodesma mactroides (Deshayes, 1854), the amphipode Phoxocephalopsis zimmeri (Schellenberg, 1931), the polychaeta Hemipodus olivieri (Orensanz & Gianuca, 1974) and the bivalve Donax gemmula (Morrison, 1971). Results indicated that benthic macrofauna zonation pattern was regular, although some changes in vertical species position along the transect was observed, mainly due to swash zone variation.
Benthic macrofauna; sandy beaches; zonation; Rio Grande do Sul
