Seasonal distribution of algal groups in sea ice. Monthly distribution of autotrophic algal groups (flagellates, and pennate and centric diatoms) is shown for all layers combined in landfast (A, C, E) and pack ice (B, D, F), separately for the Arctic (A, B) and Antarctic (C, D). Monthly distribution for heterotrophic protists is shown for landfast (E) and pack ice (F), with Arctic and Antarctic data on the same panel. Note that in several communities (e.g., in Antarctic landfast), diatoms were not distinguished in different groups in the winter months (May–July); this mixed group of diatoms was not plotted, but they make up the majority to 100%. DOI: https://doi.org/10.1525/elementa.267.f3