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Regulation of the phytoplankton heme b iron pool during the North Atlantic spring bloom

Citation

Louropoulou, E and Gledhill, M and Browning, TJ and Desai, DK and Menzel Barraqueta, J-L and Tonnard, M and Sarthou, G and Planquette, H and Bowie, AR and Schmitz, RA and LaRouche, J and Achterberg, EP, Regulation of the phytoplankton heme b iron pool during the North Atlantic spring bloom, Frontiers in Microbiology, 10 Article 1566. ISSN 1664-302X (2019) [Refereed Article]


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Copyright Statement

Copyright 2019 Louropoulou, Gledhill, Browning, Desai, Menzel Barraqueta, Tonnard, Sarthou, Planquette, Bowie, Schmitz, LaRoche and Achterberg. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/

DOI: doi:10.3389/fmicb.2019.01566

Abstract

Heme b is an iron-containing co-factor in hemoproteins. Heme b concentrations are low (<1 pmol L-1) in iron limited phytoplankton in cultures and in the field. Here, we determined heme b in marine particulate material (>0.7 μm) from the North Atlantic Ocean (GEOVIDE cruise GEOTRACES section GA01), which spanned several biogeochemical regimes. We examined the relationship between heme b abundance and the microbial community composition, and its utility for mapping iron limited phytoplankton. Heme b concentrations ranged from 0.16 to 5.1 pmol L-1 (median = 2.0 pmol L-1, n = 62) in the surface mixed layer (SML) along the cruise track, driven mainly by variability in biomass. However, in the Irminger Basin, the lowest heme b levels (SML: median = 0.53 pmol L-1, n = 12) were observed, whilst the biomass was highest (particulate organic carbon, median = 14.2 μmol L-1, n = 25; chlorophyll a: median = 2.0 nmol L-1, n = 23) pointing to regulatory mechanisms of the heme b pool for growth conservation. Dissolved iron (DFe) was not depleted (SML: median = 0.38 nmol L-1, n = 11) in the Irminger Basin, but large diatoms (Rhizosolenia sp.) dominated. Hence, heme b depletion and regulation is likely to occur during bloom progression when phytoplankton class-dependent absolute iron requirements exceed the available ambient concentration of DFe. Furthermore, high heme b concentrations found in the Iceland Basin and Labrador Sea (median = 3.4 pmol L-1, n = 20), despite having similar DFe concentrations to the Irminger Basin, were attributed to an earlier growth phase of the extant phytoplankton populations. Thus, heme b provides a snapshot of the cellular activity in situ and could both be used as indicator of iron limitation and contribute to understanding phytoplankton adaptation mechanisms to changing iron supplies.

Item Details

Item Type:Refereed Article
Keywords:phytoplankton, heme b, iron, North Atlantic, spring bloom
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Chemical Oceanography
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Biological Sciences
UTAS Author:Tonnard, M (Miss Manon Tonnard)
UTAS Author:Bowie, AR (Associate Professor Andrew Bowie)
ID Code:133887
Year Published:2019
Deposited By:Oceans and Cryosphere
Deposited On:2019-07-12
Last Modified:2019-08-05
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