Rossby waves are an important phenomenon, linking processes in the west of ocean basins with forcing that occurred earlier in the east. We show evidence for such features in satellite-derived datasets of sea-surface height, temperature and ocean colour, using a section of the south Indian Ocean as an example. We discuss the possible mechanisms for an effect on chlorophyll, and we investigate this by comparing the ocean colour signal with the other datasets. In this region, the primary mechanism for a Rossby-wave signal in ocean colour appears to be meridional advection of water across a strong chlorophyll gradient. However, this cannot fully explain the observations in the westernmost basin.