Bacterial carbon demand and growth efficiency in a coastal upwelling system

Lønborg, Christian; Martínez‐García, Sandra; Teira, Eva; Álvarez‐Salgado, Xosé Antón

doi:10.3354/ame01495

Cited by 25 publications

(16 citation statements)

References 33 publications

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“…Our calculated BGE values were strongly negatively correlated with in situ inorganic nitrogen, in contrast with the positive correlation seen in an upwelling system by Lønborg et al (), and strongly positively correlated with in situ temperature, in contrast with the negative correlations seen in a broad literature survey of the euphotic ocean (Rivkin and Legendre ) and the lack of relationship observed in a cross‐system review (del Giorgio and Cole ). We believe these disagreements are due to the distinct progression of physical and chemical properties during an intensely sampled, upwelling‐driven, short‐term phytoplankton bloom, rather than the inorganic nitrogen and temperature per se: the upwelling‐to‐bloom progression that we sampled resulted in the production of highly bioavailable DOM in relatively warm, nutrient‐poor water, setting up a contrast with the productive poles and oligotrophic tropics underlying cross‐system comparisons in the global ocean.…”

Section: Discussioncontrasting

confidence: 99%

“…As we infer an increasingly C‐rich DOM pool from the increase in DOC, there may be a relationship between BGE and DOM stoichiometry that is obscured by the bulk pool. However, in that case, our BGEs would show the opposite trend (an increase in BGE with increasing DOC : DON) of that seen by Lønborg et al (), likely due to a combination of the freshly produced nature of the DOM and the continued availability of inorganic nitrogen (Table ).…”

Section: Discussioncontrasting

confidence: 72%

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Synchronous shifts in dissolved organic carbon bioavailability and bacterial community responses over the course of an upwelling-driven phytoplankton bloom

et al. 2015

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Interactions between dissolved organic carbon (DOC) and bacterioplankton were examined during a diatom and Phaeocystis bloom in the Santa Barbara Channel (SBC) over five days following an upwelling event.The SBC was heterogeneous in physical state (recently upwelled vs. more stratified), nutrient concentration, and productivity, encompassing phytoplankton physiological states from a healthy bloom through the onset of silicon stress. DOC accumulated in the upper 10 m over the bloom, with compositional shifts indicated by chromophoric dissolved organic matter (CDOM) parameters. DOC bioavailability and bacterial growth and community composition responses were assessed with dilution batch-culture bioassays. In these experiments, bacterioplankton DOC usage increased over the bloom, with uptake of 1.5-5.3 lmol L 21 over three days, 1.5-5.7 lmol L 21 over one week, and 1.8-10.8 lmol L 21 over 10 weeks. DOC removal was poorly correlated with traditional proxies of bioavailability (chlorophyll a concentration, elemental ratios of dissolved organic matter, and CDOM). However, bacterial growth efficiency (BGE) was strongly related to in situ conditions, with higher BGEs on fresher, late-bloom DOC. After 10 weeks, 1.6-15.7 lmol L 21 of the DOC that accumulated during the bloom remained unutilized in the bioassays, with higher concentrations of persistent DOC in experiments from senescent bloom physiological states, supporting the putative relationship between phytoplankton blooms and seasonal DOC accumulation in the field. These experiments demonstrate that DOC released by the plankton community during a bloom fuels increased short-term and long-term bacterial activity, enhances presumed trophic transfer via increased BGEs, and leads to the accumulation of persistent, potentially exportable, DOC. V C 2015 Association for the Sciences of Limnology and Oceanography

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Section: Discussioncontrasting

confidence: 99%

Section: Discussioncontrasting

confidence: 72%

Synchronous shifts in dissolved organic carbon bioavailability and bacterial community responses over the course of an upwelling-driven phytoplankton bloom

et al. 2015

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“…The range in %BDOC measured in our study (Table 5) is comparable to that reported for other coastal studies (Søndergaard & Middelboe 1995, Lønborg & Søndergaard 2009, Lønborg et al 2011), but our time series revealed a strong seasonal trend. The remineralization bioassays revealed that the bioavailability of DOC was greatest during upwelling (May 2008), when 7 to 15 µM DOC was consumed over the course of 1 wk.…”

Section: Bioavailability Of Doc and Associated Bgesupporting

confidence: 91%

Annual cycle of organic matter partitioning and its availability to bacteria across the Santa Barbara Channel continental shelf

Halewood¹,

Carlson²,

Brzezinski³

et al. 2012

Aquat. Microb. Ecol.

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Seasonal trends in organic matter (OM) partitioning (between the dissolved and particulate phases), dissolved inorganic nitrogen (DIN) distributions, and bacterioplankton dynamics were examined across a 3 km stretch of the Santa Barbara Channel continental shelf from January 2008 to April 2009. OM partitioning was assessed as the percentage of 14 C-primary production (PP) released as 14 C-labeled dissolved organic carbon (DOC), i.e. percent extracellular release (PER), and as the ratio of DOC and particulate organic carbon (POC) concentrations. Spring upwelling raised surface DIN concentrations, stimulating phytoplankton blooms and OM accumulation. During upwelling, PER accounted for 10 to 30%, with ~60% of OM accumulating as POC versus ~40% as DOC. After stratification and macronutrient depletion, PER increased to between 35 and 45%, and the proportion of seasonally produced DOC to total accumulated organic carbon increased to > 50%. Experiments revealed a seasonal maximum in DOC bioavailability to heterotrophic bacterioplankton during upwelling: 9 to 18% of DOC was consumed in <1 wk at bacterial growth efficiencies (BGE) of 5 to 12%. Throughout the stratified period, ≤5% of DOC was consumed in <1 wk, and the BGE increased to between 12 and 52%. Bacterial carbon demand (BCD) ranged from 0.2 to 24 µmol C l, and for most of the sampling period, PP was sufficient to meet BCD. However, at times, BCD exceeded phytoplankton PP, indicating that sources of DOC other than daily PP were used to support BCD. Similar to other coastal systems, OM is partitioned mainly into the particulate phase under nutrient-replete conditions and into the dissolved phase following stratification and the onset of oligotrophic conditions. We discuss how the partitioning of OM has consequences for bacterial metabolism and carbon cycling of this coastal system.

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“…This allowed for all processes that govern BGE to be determined under the same conditions, but we do recognize that prefiltration, the long incubation period, and the subset of bacteria in the incubations could have affected our BGE estimates. Our low BGE is characteristic of oligo trophic waters, where maintenance energy requirements are a significant fraction of energy flow in microbial assemblages (del Giorgio & Cole 1998, Biddanda et al 2001, Alonso-Sáez et al 2007, Carlson et al 2007, Lønborg et al 2011. BGE has been found to greatly increase over an incubation period.…”

Section: Bgementioning

confidence: 73%

Effects of submarine groundwater discharge on bacterial growth efficiency in coastal Hawaiian waters

Carlson¹,

Wiegner²

2016

Aquat. Microb. Ecol.

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leasing CO 2 into the water. Identifying these patterns and variations of microbial processes is fundamental to understanding C cycling. Bacterial meta bolism indices such as bacterial growth efficiency (BGE) allow us to analyze the amount of C taken in by bacteria and determine how much is being used for biomass production that can be cycled into the food web ver-© Inter-Research 2016 • www.int-res.com

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Bacterial carbon demand and growth efficiency in a coastal upwelling system

Cited by 25 publications

References 33 publications

Synchronous shifts in dissolved organic carbon bioavailability and bacterial community responses over the course of an upwelling-driven phytoplankton bloom

Synchronous shifts in dissolved organic carbon bioavailability and bacterial community responses over the course of an upwelling-driven phytoplankton bloom

Annual cycle of organic matter partitioning and its availability to bacteria across the Santa Barbara Channel continental shelf

Effects of submarine groundwater discharge on bacterial growth efficiency in coastal Hawaiian waters

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