Qualitative samples of flora and fauna were collected in several points, from the supralittoral fringe down to 30 m, using mainly aqualungs. Species distribution and abundance were determined along four transects, up to 200 m long, in selected places. Samples were taken from 25 x 25 cm quadrats positioned at fixed intervals along the transects down to a variable depth, depending on algal percentage cover and their substrate. The intertidal zone was populated essentially by molluscs. The subtidal was covered predominantly by macroalgae. Montastrea cavernosa, Siderastrea stellata and Mussismillia hispida were the only animal species with a significant percentage cover within the quadrats. Dictyopteris justii, D. plagiograma, Dictyota cervicornis, D. linearis, D. mertensii, Sargassum platycarpum, Sargassum sp, and Stypopodium zonale were the plants with the highest biomass and/or percentage cover, along with Amphiroa fragilissima, Caulerpa verticillata, and crustose corallines. The scarcity of sea urchins, along with the dominance of algae known to produce chemical feeding deterrents or to have a calcareous nature, points towards a strong pressure by predators, with fishes probably playing a key role in the maintenance of the structure of this subtidal community.

Primary growth was analysed on artificial substrata submerged at three sites of the Santos estuary (State of São Paulo, Brazil). Research on sessile ciliates was emphasized because they were the most conspicuous organisms of the primary growth developed along this estuary. Zoothamnium commune, dominated near the headwaters of the estuary, where the greatest amount of suspended matter in the water was found. Ephelota gemmipara dominated downstream. Although short time variability was observed in the colonization of substrata submerged on subsequent days, seasonal patterns could be determined. These patterns were characterized by a greater number of rare species of sessile ciliates, and a higher density of the most frequent ones, during spring and summer.