Most common microorganisms identified at the different stations.

Microscopic estimates of cell abundances, mean phytoplankton cell sizes (expressed as cell area), and percentage of cells showing uptake of 3H-leucine (Leu) or 35S-DMSP (average ± standard error of the three treatments, ‘nd’, not determined). Data in bold (averages ± standard error of the three treatments) indicate that significant differences (Tukey’s test pResults). Thalassiosira sp. A was so named to differentiate it from species B, C and D from station AN1, but sp. A from different stations was probably not the same species.