Abstract Rapid climate change in the Western Antarctic Peninsula (WAP) has driven fundamental shifts in phytoplankton communities. To assess variability of the phytoplankton community in Marian Cove, WAP, diagnostic pigments were analyzed for CHEMical TAXonomy. The dominant phytoplankton groups—diatoms, cryptophytes and Phaeocystis spp.—showed shifts in their relative contributions depending on zonal wind direction. Easterly winds transported large-sized (20 μm) benthic diatoms into the water column, contributing up to 51% of the total phytoplankton biomass. In contrast, during prevailing westerly winds, the relative contributions of nano-sized cryptophytes and Phaeocystis spp. increased from 13% to 21% and from 3% to 16%, respectively. Westerly winds facilitated the influx of nanoflagellates from outside Marian Cove, resulting in a reduction in phytoplankton size spectrum. Therefore, diatoms and cryptophytes exhibited complementary distributions. Notably, the contribution of cryptophytes was significantly correlated with westerly wind stress (r = −0.50, P 0.01). This relationship has become more pronounced compared to historical observations from 2005 to 2010 in Marian Cove. This trend indicates an increasing dominance of cryptophytes under intensifying westerlies associated with the positive phase of the Southern Annular Mode. These findings suggest that cryptophyte-dominated systems could have cascading ecological effects on the vulnerable WAP ecosystem.
Shim et al. (Tue,) studied this question.