Phenotypic Variability in the Coccolithophore Emiliania huxleyi

Abstract

Coccolithophores are a vital part of oceanic phytoplankton assemblages that produce organic matter and calcium carbonate (CaCO3) containing traces of other elements (i.e. Sr and Mg). Their associated carbon export from the euphotic zone to the oceans' interior plays a crucial role in CO2 feedback mechanisms and biogeochemical cycles. The coccolithophore Emiliania huxleyi has been widely studied as a model organism to understand physiological, biogeochemical, and ecological processes in marine sciences. Here, we show the inter-strain variability in physiological and biogeochemical traits in 13 strains of E. huxleyi from various biogeographical provinces obtained from culture collections commonly used in the literature. Our results demonstrate that inter-strain genetic variability has greater potential to induce larger phenotypic differences than the phenotypic plasticity of single strains cultured under a broad range of variable environmental conditions. The range of variation found in physiological parameters and calcite Sr:Ca highlights the need to reconsider phenotypic variability in paleoproxy calibrations and model parameterizations to adequately translate findings from single strain laboratory experiments to the real ocean.

The mutual interplay between calcification and coccolithovirus infection

“…Corresponding CaCO 3 : POC ratios for these strains ranged from 0.04 to 0.55 ( Fig. 1E), consistent with previous ratios reported for E. huxleyi (Blanco-Ameijeiras et al, 2016). Emiliania huxleyi host strains displayed distinct differences in host-virus infection dynamics when challenged with the coccolithovirus type strain EhV86 (Fig.…”

“…Corresponding CaCO 3 :POC ratios for these strains ranged from 0.04 to 0.55 (Fig. E), consistent with previous ratios reported for E. huxleyi (Blanco‐Ameijeiras et al ., ).…”

Emerging Interaction Patterns in the Emiliania huxleyi-EhV System

“…Such an infection mechanism potentially generates a highly lipid-specific contact between host and virus. The host, E. huxleyi , has high phenotypic plasticity [104,105,106,107,108] and adaptation capacity [104,109,110,111,112] that could result in ecotypes that respond differently to viral infection [37,108,112]. Even if genes associated with virus susceptibility have been found within non-core regions of the E. huxleyi genome [108], our results did not show significant differences in growth rate, resistance, or viral production in hosts from very distant geographical locations.…”

Day length as a key factor moderating the response of coccolithophore growth to elevated pCO2

“…The functional groupings we observed for the interactive photoperiod‐ p CO 2 responses at face value appear to correspond with biogeographic origin, i.e., “temperate” ( E. huxleyi stains NZEH, 70‐3, and 124‐3 and C. braarudii ) vs. “tropical” ( E. huxleyi stain RCC962 and G. oceanica ) isolated species (see Table ). Considerable phenotypic variability is known to exist between isolates of E. huxleyi (Iglesias‐Rodriguez et al ; Müller et al ), although past efforts have failed to fully reconcile differences in isolate environmental history with OA responses (Langer et al ; Findlay et al ; Blanco‐Ameijeiras et al ). Furthermore, the previous p CO 2 responses under both 14 : 10 h and continuous light regimes for the temperate E. huxleyi strain B92/11 (Rost et al , ; Zondervan et al ) are arguably more similar to those for our “tropical” then “temperate” isolates.…”