Single-cell metabarcoding reveals biotic interactions of the Arctic calcifierNeogloboquadrina pachydermawith the eukaryotic pelagic community

Abstract

Isotopic and trace-element signals in the calcite shells of the planktonic foraminifera Neogloboquadrina pachyderma represent key proxies to reconstruct past climatic conditions in northern high latitudes. A correct interpretation of these chemical signals requires knowledge of the habitat and trophic interactions of the species. Direct observations on the biological interactions of N. pachyderma in polar environments are lacking and to date no consensus exists on the trophic behaviour of this species. Here we use single-cell metabarcoding to characterise the interactions of 39 specimens of N. pachyderma from two sites in the Baffin Bay with the local eukaryotic pelagic community. Our results show that the eukaryotic interactome of the foraminifera is dominated by diatoms, accounting for > 50% of the reads in 17 of the samples, but other groups such as Crustacea and Syndiniales are also present. The high abundance Syndiniales suggests that these parasites could infect N. pachyderma and may play an important role in its population dynamics. Moreover, the strong but taxonomically non-specific association with algae, existing irrespective of depth and occurring in specimens collected far below the photic zone indicates that opportunistically grazed diatom-fuelled marine aggregates likely represent the main interaction substrate of N. pachyderma.

Exploring the impact of climate change on the global distribution of non‐spinose planktonic foraminifera using a trait‐based ecosystem model

“…Our model does not capture foraminifera's standing stocks in the modern polar Southern Ocean. We speculate that this is due to the lack of an omnivorous/detritus diet of polar non‐spinose species (Greco et al, 2021) or other polar traits such as dormancy (Dieckmann et al, 1991; Spindler & Dieckmann, 1986) and thermal tolerance. It is thus crucial that future studies include different foraging strategies and the symbiotic relationship with algae to study the foraminifera distribution and their potential vulnerability in the future.…”

“…Spinose adult species (with the exception of Globigerina bulloides ) are predominantly carnivorous and most abundant in oligotrophic regions (Schiebel & Hemleben, 2017). In contrast, adults of non‐spinose species are mostly herbivorous and potentially supplement their diet with organic matter and animal prey (dead or alive, Anderson et al, 1979; Greco et al, 2021; Schiebel & Hemleben, 2017). Non‐spinose species are most abundant in highly productive areas (Figure 1a; Bé & Tolderlund, 1971).…”

Increased Productivity in the Equatorial Pacific During the Deglaciation Inferred From the Ba/Ca Ratios of Non‐Spinose Planktic Foraminifera

“…We favor the hypothesis that the elevated Ba/Ca ratios in the non-spinose species are due to calcification in Ba-enriched POM. Non-spinose foraminifera are often found attached or embedded within POM (Davis et al, 2020;Fehrenbacher et al, 2018), perhaps as a feeding mechanism, as non-spinose species are believed to feed on sinking aggregates of phytoplankton remains (e.g., Anderson et al, 1979;Greco et al, 2019Greco et al, , 2021Spindler et al, 1984;Takagi et al, 2019). Foraminifera likely inhabit a Ba-enriched environment for a portion of their lifecycle (e.g., while feeding) and spend a portion of their lifecycle in seawater prior to gametogenesis when it is observed that the rhizopodia they use to attach to POM are retracted (Fehrenbacher et al, 2018;Schiebel & Hemleben, 2017).…”

Mitochondrial cytochrome c oxidase subunit I (COI) metabarcoding of Foraminifera communities using taxon-specific primers

“…Molecular metabarcoding, i.e. , the amplification, sequencing and analysis of whole communities ( Taberlet et al, 2012 ), is commonly applied to Foraminifera communities to detect species diversity in a wide range of ecosystems ( Pawlowski, Lejzerowicz & Esling, 2014 ; Morard et al, 2019 ; Holzmann et al, 2021 ), for environmental impact assessments ( Pawlowski et al, 2014 ; Laroche et al, 2016 ; Frontalini et al, 2018 ) and to study the ecology of Foraminifera ( He et al, 2019 ; Chronopoulou et al, 2019 ; Greco, Morard & Kucera, 2020 ). Until recently, only one genetic marker, the nuclear 18S ribosomal RNA (the small subunit ribosomal ribonucleic acid; SSU), has been used for barcoding and metabarcoding of Foraminifera.…”