Elemental quotas and physiology of a southwestern Pacific Ocean plankton community as a function of iron availability

Wilhelm, Steven W.; King, Andrew L.; Twining, Benjamin S.; LeCleir, Gary R.; DeBruyn, Jennifer M.; Strzepek, Robert F.; Breene, Cynthia L.; Pickmere, S.; Ellwood, Michael J.; Boyd, Philip W.; Hutchins, David A.

doi:10.3354/ame01611

Cited by 24 publications

(16 citation statements)

References 60 publications

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“…The Chaetoceros-like diatoms had a~threefold variation in iron quotas with time and hence with changing dissolved iron concentrations and availability ( Figure 6). This latter range of iron quotas is of the same order as those reported for natural phytoplankton communities in response to purposeful iron enrichment in shipboard [Wilhelm et al, 2013] and mesoscale in situ [Twining et al, 2004] studies.…”

Section: Ecological Controls On Iron Quotas In the Ocean?supporting

confidence: 75%

Why are biotic iron pools uniform across high‐ and low‐iron pelagic ecosystems?

Boyd

Strzepek

Ellwood

et al. 2015

Global Biogeochemical Cycles

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Dissolved iron supply is pivotal in setting global phytoplankton productivity and pelagic ecosystem structure. However, most studies of the role of iron have focussed on carbon biogeochemistry within pelagic ecosystems, with less effort to quantify the iron biogeochemical cycle. Here we compare mixed-layer biotic iron inventories from a low-iron (~0.06 nmol L À1 ) subantarctic (FeCycle study) and a seasonally high-iron (~0.6 nmol L À1 ) subtropical (FeCycle II study) site. Both studies were quasi-Lagrangian, and had multi-day occupation, common sampling protocols, and indirect estimates of biotic iron (from a limited range of available published biovolume/carbon/iron quotas). Biotic iron pools were comparable (~100 ± 30 pmol L À1) for low-and high-iron waters, despite a tenfold difference in dissolved iron concentrations. Consistency in biotic iron inventories (~80 ± 24 pmol L À1, largely estimated using a limited range of available quotas) was also conspicuous for three Southern Ocean polar sites. Insights into the extent to which uniformity in biotic iron inventories was driven by the need to apply common iron quotas obtained from laboratory cultures were provided from FeCycle II. The observed twofold to threefold range of iron quotas during the evolution of FeCycle II subtropical bloom was much less than reported from laboratory monocultures. Furthermore, the iron recycling efficiency varied by fourfold during FeCycle II, increasing as stocks of new iron were depleted, suggesting that quotas and iron recycling efficiencies together set biotic iron pools. Hence, site-specific differences in iron recycling efficiencies (which provide 20-50% and 90% of total iron supply in high-and low-iron waters, respectively) help offset the differences in new iron inputs between low-and high-iron sites. Future parameterization of iron in biogeochemical models must focus on the drivers of biotic iron inventories, including the differing iron requirements of the resident biota, and the subsequent fate (retention/export/recycling) of the biotic iron.

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Section: Ecological Controls On Iron Quotas In the Ocean?supporting

confidence: 75%

Why are biotic iron pools uniform across high‐ and low‐iron pelagic ecosystems?

Boyd

Strzepek

Ellwood

et al. 2015

Global Biogeochemical Cycles

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“…By having a prolonged period of monitoring, it allowed to observe the full response from the diatom in all treatments, which would otherwise have been missed with a shorter timeframe. Such observation may aid in reconciling some of the contrasting results between studies that reported very low or negligible growth both in natural community and culture experiments (Wells et al, 1994;Eldridge et al, 2007;Hassler et al, 2011Hassler et al, , 2015Wilhelm et al, 2013).…”

Section: Skeletonema Costatum Response To Fedfb Boundmentioning

confidence: 63%

Effect of Siderophore on Iron Availability in a Diatom and a Dinoflagellate Species: Contrasting Response in Associated Bacteria

et al. 2018

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Organic ligands play a key role controlling trace metal bioavailability in the world's oceans, yet the species-specific requirements determining whether certain iron forms can be metabolized largely remain unclear. Siderophores are considered relevant within the pool of ligands keeping iron soluble. We used desferrioxamine B (DFB) to study the siderophore's effect on cultures of Skeletonema costatum and Alexandrium catenella. The experimental approach used semi-continuous additions of iron(II) and DFB over time, reaching final concentrations of 1 and 10 nM Fe and 10-10,000 nM DFB. The negative effect of DFB on growth in S. costatum was evident and sharp until day 9 for treatments above 500 nM. Delayed growth occurred at 10,000 nM, reaching ∼80% of cell density in Controls under both iron conditions. Alexandrium catenella exhibited a less severe negative effect of DFB on growth, only significant at 10,000 nM, while growth was enhanced at lowest DFB. Total bacterial abundance in diatom and dinoflagellate cultures presented inverse trends. While negatively correlated to DFB in diatom cultures, bacteria showed highest abundances in high DFB treatments in dinoflagellate cultures. Delayed growth exhibited in S. costatum at the highest DFB, indicates that favorable changes for Fe uptake occurred over time, suggesting the involvement of other mechanisms facilitating the diatom cell membrane reduction. Overall, unaffected growth in A. catenella suggests that this species can use FeDFB and therefore has the capacity to access strongly complexed Fe sources. Contrasting responses in the bacterial community associated with each species highlight the complexity of these interactions, while suggesting that for A. catenella it may represent an advantage for acquiring Fe. These results demonstrated the capacity for different uptake strategies among phytoplankton species of different functional groups and underlines the necessity to broaden the study of iron bioavailability on a species basis, alongside interaction with other microbial components such bacteria, to reflect interactions in natural ecosystems.

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“…Gall, submitted) were constructed to collect particles and here are used to monitor the development of, and changes to, the marine‐snow‐associated bacterial community in situ . We describe the use of these traps to characterize changes in the particle‐associated microbial communities compared with free‐living bacterial communities in the water column during an initial diatom bloom and a secondary bloom codominated by cyanobacteria and diatoms, while the system transitioned from iron‐replete to iron‐limiting conditions (Wilhelm et al ., ).…”

Section: Introductionmentioning

confidence: 97%

Temporal changes in particle-associated microbial communities after interception by nonlethal sediment traps

LeCleir

DeBruyn

Maas

et al. 2013

FEMS Microbiol Ecol

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Using marine sediment traps (named RESPIRE for REspiration of Sinking Particles In the subsuRface ocEan) designed to collect sinking particles and associated microbial communities in situ, we collected and incubated marine aggregates/particles in the southern Pacific Ocean from separate phytoplankton bloom events in situ. We determined the phylogenetic affiliation for the microorganisms growing on aggregates by pyrosequencing partial 16S rRNA gene amplicons. Water column samples were also collected and sequenced for comparison between sinking-particle-associated and planktonic bacterial communities. Statistically significant differences were found between the water column and sediment trap bacteria. Relative abundances of Pelagibacter sp. and multiple members of the Flavobacteria, Actinobacteria, and α-Proteobacteria were elevated in water column samples, while trap samples contained members of the Roseobacter clade of α-Proteobacteria in high relative abundances. Our findings indicated that rapid changes - within 24 h of collection - occurred to the microbial community associated with aggregates from either bloom type. There was a little change in the bacterial assemblage after the initial 24-h incubation period. The most abundant early colonizer was a Sulfitobacter sp. This study provides further evidence that Roseobacters are rapid colonizers of marine aggregates and that colonization can occur on short timescales. This study further demonstrates that particle origin may be insignificant regarding the heterotrophic bacterial population that degrades them.

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Elemental quotas and physiology of a southwestern Pacific Ocean plankton community as a function of iron availability

Cited by 24 publications

References 60 publications

Why are biotic iron pools uniform across high‐ and low‐iron pelagic ecosystems?

Why are biotic iron pools uniform across high‐ and low‐iron pelagic ecosystems?

Effect of Siderophore on Iron Availability in a Diatom and a Dinoflagellate Species: Contrasting Response in Associated Bacteria

Temporal changes in particle-associated microbial communities after interception by nonlethal sediment traps

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