Exopolysaccharides produced by bacteria isolated from the pelagic Southern Ocean — Role in Fe binding, chemical reactivity, and bioavailability

Hassler, Christel; Alasonati, Enrica; Nichols, C.A. Mancuso; Slaveykova, Vera I.

doi:10.1016/j.marchem.2010.10.003

Cited by 105 publications

(106 citation statements)

References 79 publications

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“…The recycling of Fe (and iron-binding ligands) is rapid (hours to days) and occurs through grazing, phytoplankton lysis, bacterial and viral infections (Barbeau et al, 1996;Poorvin et al, 2004;Strzepek et al, 2005), as well as active excretion and transformation of organic compounds (e.g., Trick and Wilhelm, 1995;Ogawa et al, 2001;Hassler et al, 2011b). In the remote SO where external sources of Fe are limited, Fe recycling is efficient, providing 20-100% of the Fe required to sustain phytoplankton growth (Hutchins et al, 1993;Poorvin et al, 2004;Strzepek et al, 2005;Sarthou et al, 2005).…”

Section: Iron (Fe) Limitationmentioning

confidence: 99%

Southern Ocean phytoplankton physiology in a changing climate

Petrou

Kranz

Trimborn

et al. 2016

Journal of Plant Physiology

119

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Please cite this article in press as: Petrou, K., et al., Southern Ocean phytoplankton physiology in a changing climate. J Plant Physiol (2016), http://dx.doi.org/10.1016/j.jplph.2016.05.004 ARTICLE IN PRESS a b s t r a c tThe Southern Ocean (SO) is a major sink for anthropogenic atmospheric carbon dioxide (CO 2 ), potentially harbouring even greater potential for additional sequestration of CO 2 through enhanced phytoplankton productivity. In the SO, primary productivity is primarily driven by bottom up processes (physical and chemical conditions) which are spatially and temporally heterogeneous. Due to a paucity of trace metals (such as iron) and high variability in light, much of the SO is characterised by an ecological paradox of high macronutrient concentrations yet uncharacteristically low chlorophyll concentrations. It is expected that with increased anthropogenic CO 2 emissions and the coincident warming, the major physical and chemical process that govern the SO will alter, influencing the biological capacity and functioning of the ecosystem. This review focuses on the SO primary producers and the bottom up processes that underpin their health and productivity. It looks at the major physico-chemical drivers of change in the SO, and based on current physiological knowledge, explores how these changes will likely manifest in phytoplankton, specifically, what are the physiological changes and floristic shifts that are likely to ensue and how this may translate into changes in the carbon sink capacity, net primary productivity and functionality of the SO.

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Section: Iron (Fe) Limitationmentioning

confidence: 99%

Southern Ocean phytoplankton physiology in a changing climate

Petrou

Kranz

Trimborn

et al. 2016

Journal of Plant Physiology

119

View full text Add to dashboard Cite

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“…Though it isn't clearly known what forms weak ligands, previous studies have implied that they may be a combination of degraded cellular material from seawater (Hunter and Boyd, 2007), like polysaccharides (Hassler et al, 2011), thiols, and heme (Hopkinson et al, 2008).…”

Section: Iron-complexing Organic Ligandsmentioning

confidence: 99%

Distribution and Speciation of Dissolved Iron in Jiaozhou Bay (Yellow Sea, China)

Yang

Pižeta

et al. 2016

Front. Mar. Sci.

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The distribution of total dissolved iron (DFe) and its chemical speciation were studied in vertical profiles of the shallow and semi-closed Jiaozhou Bay (JZB, China) during two contrasting periods: summer (July 19 th , 2011) and spring (May 10 th , 2012). Samples collected from the surface, middle and bottom layers were analyzed by competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-aCSV). The mean DFe concentration during the summer period (median 18.8 nM; average 20.7 nM) was higher than in the spring period (median 12.4 nM; average 16.9 nM), whereas the spatio-temporal variation in spring was larger than in summer. The DFe-values showed distinct regional and seasonal differences, ranging from 5.6 to 107 nM in spring period and 13.4 to 43.4 nM in summer period. In spring, the highest DFe-values were observed in the eastern coastal region, especially near an industrial area (up to 107 nM), whereas the DFe distribution in summer was relatively even. Due to a tide influence, the vertical variations in the DFe and L t in both seasons were not significant. On average, the L t concentration (one class of ligand was estimated in all samples), was higher in spring (35.2 ± 23.4 nM) than in summer (31.1 ± 10.3 nM). A statistically significant correlation was found between L t and DFe concentrations, it was higher for the summer period than for the spring period. The conditional stability constants (logK ′ ) of organic complexes with iron were weaker in spring (11.7 ± 0.3) than in summer (12.3 ± 0.3). The concentrations of L t were higher in comparison to DFe in all samples: the average [L t ]/[DFe] ratio in the spring and summer samples was 2.4 and 1.5, respectively. Speciation calculations showed that the DFe in the JZB existed predominantly (over 99.99%) in the form of strong organic complexes in both seasons.

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“…Phytoplankton and other microorganisms during the spring and summer generate huge quantities of organic matter during growth and subsequent senescence (Pusceddu et al, 1999). The residence time of bioavailable Fe may be increased by the presence of exopolysaccharides (EPS, Hassler et al, 2011aHassler et al, , 2011b released by microorganisms in the upper waters that act as Fe-binding ligand, thereby extending the phytoplankton blooms. Degradation and remineralization of organic matter aid in the regeneration of ligands (Gerringa et al, 2006), hence participating in the regeneration of Fe from senescent phytoplankton in surface waters, but also in enriching deep waters with organic matter and thus organic ligands.…”

Section: Phytoplankton Bloommentioning

confidence: 99%