Indices based on silicoflagellate assemblages offer potential for paleo-reconstructions of the main oceanographic zones of the Southern Ocean

Seasonal and Geographical Transitions in Eukaryotic Phytoplankton Community Structure in the Atlantic and Pacific Oceans

“…Because the dominant clades observed at BATS and the ENP lack cultured representatives, it remains unclear whether the capacity to feed via phagocytosis extends across dictyochophyte diversity. However, as with diatoms (Durkin et al, 2016), which were low in relative abundance at our study sites, dictyochophyte silicification has been associated with efficient carbon export (Marron et al, 2016;Rigual-Hernandez et al, 2016).…”

“…Likewise, our knowledge of dictyochophyte pigment composition (Daugbjerg and Henriksen, 2001;Eikrem et al, 2004;Chang et al, 2012), and silicoflagellate cell structure (Henriksen et al, 1993), comes from cultured species. Silicoflagellates have served as paleoecological markers, due to their distinct silicate skeletons (Rigual-Hernandez et al, 2016), and have been shown to be common in nutrient rich, high-latitude environments by HPLC and light microcopy (van de Poll et al, 2018). The Dictyochales order as a whole takes a basal position within the dictyochophyte phylogeny (Supplementary Figure S5).…”

“…They have few cultured representatives, little biogeographical data apart from TARA ( de Vargas et al, 2015 ), and little seasonal data. This group contains the silicoflagellates, which can be microscopically identified by their distinctive siliceous skeletons, and have been studied mainly in coastal northern ecosystems and sediments or as paleoecological markers ( Henriksen et al, 1993 ; Rigual-Hernandez et al, 2016 ; van de Poll et al, 2018 ). Indeed, there are few oceanic time-series analyses that tease apart the contributions of diatoms, chrysophytes, and pelagophytes, and more newly discovered groups like bolidophytes ( Goericke, 1998 ; Steinberg et al, 2001 ; Lomas et al, 2013 ), or those with few cultured representatives, like the dictyochophytes.…”