Full annual monitoring of Subantarctic Emiliania huxleyi populations reveals highly calcified morphotypes in high-CO 2 winter conditions

Ocean acidification is expected to have detrimental consequences for the most abundant calcifying phytoplankton species Emiliania huxleyi . However, this assumption is mainly based on laboratory manipulations that are unable to reproduce the complexity of natural ecosystems. Here, E. huxleyi coccoli...

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Bibliographic Details
Published in:Scientific Reports
Main Authors: Rigual-Hernandez, AS, Trull, TW, Flores, JA, Nodder, SD, Eriksen, R, Davies, DM, Hallegraeff, GM, Sierro, FJ, Patil, SM, Cortina, A, Ballegeer, AM, Northcote, LC, Abrantes, F, Rufino, MM
Format: Article in Journal/Newspaper
Language:English
Published: Nature Publishing Group 2020
Subjects:
Biological Sciences
Plant biology
Phycology (incl. marine grasses)
Ocean acidification
Online Access:https://doi.org/10.1038/s41598-020-59375-8
http://www.ncbi.nlm.nih.gov/pubmed/32054880
http://ecite.utas.edu.au/137468
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Summary:Ocean acidification is expected to have detrimental consequences for the most abundant calcifying phytoplankton species Emiliania huxleyi . However, this assumption is mainly based on laboratory manipulations that are unable to reproduce the complexity of natural ecosystems. Here, E. huxleyi coccolith assemblages collected over a year by an autonomous water sampler and sediment traps in the Subantarctic Zone were analysed. The combination of taxonomic and morphometric analyses together with in situ measurements of surface-water properties allowed us to monitor, with unprecedented detail, the seasonal cycle of E. huxleyi at two Subantarctic stations. E. huxleyi subantarctic assemblages were composed of a mixture of, at least, four different morphotypes. Heavier morphotypes exhibited their maximum relative abundances during winter, coinciding with peak annual TCO 2 and nutrient concentrations, while lighter morphotypes dominated during summer, coinciding with lowest TCO 2 and nutrients levels. The similar seasonality observed in both time-series suggests that it may be a circumpolar feature of the Subantarctic zone. Our results challenge the view that ocean acidification will necessarily lead to a replacement of heavily-calcified coccolithophores by lightly-calcified ones in subpolar ecosystems, and emphasize the need to consider the cumulative effect of multiple stressors on the probable succession of morphotypes.

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