The role of meteorological events and hydrography in determining changes to the phytoplankton community was investigated in an embayment exposed to a narrow band of coastal upwelling. Daily sampling demonstrated the importance of advective processes driven by meteorological forcing in controlling rapid shifts in the biomass and species composition of the phytoplankton community. Samples of similar phytoplankton composition were associated with different stages of the upwelling cycle, as defined by an index of biological ageing of upwelled waters. Relationships between the physical, chemical and biologicalfieldswere defined from time-senes measurements. The time elapsed following upwelling, required for the determination of biological rates, was estimated from the rate of heating. A primary production estimate of 2.14 g C nv2 daytextasciicircum was derived from determination of the rate of nutrient depletion, whereas a phytoplankton biomass-nutrient consumption equation provided an estimate of 3 92 g C m 2 day"'. Both rates were within the range of estimates obtained from in vitro tracer methods.