Surf-zone ChlorophyllaVariability at Cassino Beach, Southern Brazil

Chlorophylla, water temperature, salinity, seston weight and dissolved inorganic nutrients (silicate, phosphate, nitrite+nitrate) were measured every other day between 30 April and 31 July 1987, in the surf-zone at a fixed point of the exposed sandy beach Cassino (32°10′S, 52°10′W). Chlorophyllavariability showed two phases: (1) from 30 April to mid-May chlorophyllaconcentration was variable but high, with concentrations up to 1647 μg l−1, and brown coloured patches of the surf-zone diatomAsterionellopsis glacialiswere conspicuous with cell concentration up to 7•09 108cells l−1; (2) from mid-May to the end of July chlorophyllaconcentration was low and brown coloured patches were not observed. The results of this study indicate that the mesoscale variability of chlorophyllaand accumulation of patches is primarily controlled by exogenous meteorological factors such as wind direction and velocity, where southerly onshore winds act as the main factor accumulating cells in the surf-zone at Cassino Beach