Southern Ocean waters reveal distinct nutrient recycling pathways during decades-long journeys north
The Southern Ocean may seem far removed from the North Pacific or the Gulf of Maine, but its waters are linked to all the world's major ocean basins through a vast circulation system.
Southern Ocean waters, far from the North Pacific and Gulf of Maine, are interconnected through a vast circulation system driven by winds and currents. As deep waters rise towards the surface during winter mixing, distinct water masses form and are subsequently drawn back beneath the surface, embarking on a multi-decade journey northward.
A new study led by Bigelow Laboratory for Ocean Sciences scientists examines how two major Southern Ocean water masses, Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW), recycle nutrients during this long journey. The research, published in the Journal of Geophysical Research: Oceans, reveals that SAMW and AAIW follow distinct nutrient recycling pathways, potentially influencing the composition and productivity of phytoplankton communities across the global ocean.
The findings highlight that SAMW regenerated nitrate and phosphate faster than AAIW, while silicate regeneration occurred more rapidly in AAIW. These differences could have significant implications for phytoplankton communities, with faster nitrogen and phosphorus regeneration supporting non-silicate-utilizing phytoplankton like coccolithophores and dinoflagellates, and greater silicate regeneration favoring diatoms.
The study also noted changes in temperature and salinity associated with the age of the water masses, providing a record of how ocean properties have shifted over several decades.
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