Fig. 4: Average values of annual phenological metrics obtained for the growing cycle (September to April) from 1998 to 2022 in the Ross Sea.

a Bloom Start (BStart; week of the year; week when bloom begins); b Bloom End (BEnd; week of the year; week when bloom ends); c Bloom Duration (BDuration; number of weeks; difference between the end and beginning of bloom); d Bloom Biomass (BArea; chl-a (mg m⁻³); accumulated production of the main bloom). Although the data in (a and b) are presented on a weekly scale, d the legend displays months for reference. Different colours represent different months. The methodology used to determine these metrics is described in Section “Phytoplankton phenology metrics”.