Notice how the upwelling area exhibits higher chlorophyll levels. However, the phytoplankton bloom does not exactly correspond to the upwelled water signal. This imperfect correlation occurs for two reasons: 1) it takes time for the phytoplankton to respond to the upwelled nutrients, so there is an offset in time between the two features, and 2) phytoplankton may also obtain nutrients from other sources, such as terrestrial runoff, for growth.

Despite these potentially confounding variables, a strongly coordinated biological response to the upwelling event can clearly be seen!