A bloom of loricate choanoflagellates was recorded for the first time in the Ross Sea polynya during the austral summer 2017. Both individual cells and uncommon large-size colonies (200 μm length) represent the 42-55% of the total plankton community (i.e. specimens from 5 to 150 μm length). Choanoflagellates serve as a link between low and mid trophic levels since they prey on bacteria and in turn are ingested by zooplankton. This twofold role and the unusual abundance recorded in the Antarctic ecosystem may have relevant but still unknown effects on food web structure and dynamics in that area.
Keywords: Acanthoecidae; Antarctica; colonies; food web.
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