Phytoplankton, microscopic marine algae that photosynthesize, facilitate the sequestration of carbon dioxide from the atmosphere into the ocean, thus contributing to the regulation of global climate. In the Southern Ocean, phytoplankton productivity is limited by micronutrients, including iron.

Light is also important, because it undergoes such strong seasonal extremes. The relative dominance of iron and light limitation on phytoplankton growth is important to our understanding of how primary production, and the sequestration of carbon dioxide, will change in a future warming ocean. Program researchers conducted a series of incubation experiments during a research voyage off East Antarctica to investigate iron and light limitation in the austral summer. Our results show that, while light was the primary limiting factor of phytoplankton growth, iron favoured growth only under high light conditions.

Our results provide new insight into these processes from a poorly sampled area of the Southern Ocean, improving our understanding of how phytoplankton production will change in the future.

Vives, C.R., Schallenberg, C., Strutton, P.G., Westwood, K.J., 2022. Iron and light limitation of phytoplankton growth off East Antarctica. Journal of Marine Systems 234, 103774.