Abstract. The appearance of phytoplankton blooms within sea ice cover is of high importance considering the upper ocean primary production that
controls the biological pump, with implications for atmospheric CO2
and global climate. Satellite-derived chlorophyll a concentration showed
unprecedented phytoplankton blooms in the Maud Rise polynya, Southern Ocean,
with chlorophyll a reaching up to 4.67 mg m−3 during 2017.
Multi-satellite data indicated that the bloom appeared for the first time since
the entire mission records started in 1978. An Argo float located in the
polynya edge provided evidence of bloom conditions in austral spring 2017
(chlorophyll a up to 5.47 mg m−3) compared to the preceding years with
prevailing low chlorophyll a. The occurrence of bloom was associated with the
supply of nutrients into the upper ocean through Ekman upwelling (driven
by wind stress curl and cyclonic ocean eddies) and improved light conditions of
up to 61.9 einstein m−2 d−1. The net primary production from the
Aqua Moderate Resolution Imaging Spectroradiometer chlorophyll-based
algorithm showed that the Maud Rise polynya was as productive as the
Antarctic coastal polynyas, with carbon fixation rates reaching up to
415.08 mg C m−2 d−1. The study demonstrates how the
phytoplankton in the Southern Ocean (specifically over the shallow
bathymetric region) would likely respond in the future under warming
climate conditions and continued melting of Antarctic sea ice.
Satellite observations of new phytoplankton blooms in the Maud Rise Polynya, Southern Ocean