Iron stimulation of Antarctic bacteria

Pakulski, J. Dean; Coffin, Richard B.; Kelley, Cheryl A.; Holder, Sonya L.; Downer, Roswell; Aas, Peter; Lyons, M. Maille; Jeffrey, Wade H.

doi:10.1038/383133b0

Cited by 122 publications

(87 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our results from the naturally Fe-fertilized region off the Kerguelen Islands add to incubation experiments performed in prominent HNLC regions of the Southern Ocean (Church et al, 2000;Hutchins et al, 2001;Jain et al, 2015) and the Pacific Ocean (Hutchins et al, 2001;Kirchman et al, 2000;Agawin et al, 2006;Kuparinen et al, 2011;Price et al, 1994), as well as in high-nutrient waters off Antarctica such as the Gerlache Strait (Pakulski et al, 1996) and the Ross Sea (Bertrand et al, 2011;see Table 2 for an overview). These previous studies reveal an interesting pattern that appears to be set, in part, by the dark or light incubation regime.…”

Section: Spatial and Temporal Variability In Fe Limitationmentioning

confidence: 97%

“…Only a few studies have examined the potential role of Fe as a limiting factor for heterotrophic bacteria in dark incubations, with those studies reporting contrasting results. While Fe addition alone did not lead to enhanced bacterial production and growth in HNLC areas such as the coastal Californian and subarctic Pacific Agawin et al, 2006), in different frontal zones south of Tasmania (Church et al, 2000) and south of the polar front in the Indian sector of the Southern Ocean (Jain et al, 2015), bacterial activity increased upon Fe addition in the Gerlache Strait (Pakulski et al, 1996) and the Ross Sea (Bertrand et al, 2011). Heterotrophic bacterial abundance revealed only a minor response to Fe amendments in incubations performed within the Fe-enriched patch during a mesoscale fertilization experiment in the Pacific Ocean (Agawin et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fe and C co-limitation of heterotrophic bacteria in the naturally fertilized region off the Kerguelen Islands

2015

View full text Add to dashboard Cite

Abstract. It has been univocally shown that iron (Fe) is the primary limiting nutrient for phytoplankton metabolism in high-nutrient, low-chlorophyll (HNLC) waters, yet the question of how this trace metal affects heterotrophic microbial activity is far less understood. We investigated the role of Fe for bacterial heterotrophic production and growth at three contrasting sites in the naturally Fe-fertilized region east of the Kerguelen Islands and at one site in HNLC waters during the KEOPS2 (Kerguelen Ocean and Plateau Compared Study 2) cruise in spring 2011. We performed dark incubations of natural microbial communities amended either with iron (Fe, as FeCl 3 ) or carbon (C, as trace-metal clean glucose), or a combination of both, and followed bacterial abundance and heterotrophic production for up to 7 days. Our results show that single and combined additions of Fe and C stimulated bulk and cell-specific bacterial production at the Fe-fertilized sites, while in HNLC waters only combined additions resulted in significant increases in these parameters. Bacterial abundance was enhanced in two out of the three experiments performed in Fe-fertilized waters but did not respond to Fe or C additions in HNLC waters. Our results provide evidence that both Fe and C are present at limiting concentrations for bacterial heterotrophic activity in the naturally fertilized region off the Kerguelen Islands in spring, while bacteria were co-limited by these elements in HNLC waters. These results shed new light on the role of Fe in bacterial heterotrophic metabolism in regions of the Southern Ocean that receive variable Fe inputs.

show abstract

Section: Spatial and Temporal Variability In Fe Limitationmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Fe and C co-limitation of heterotrophic bacteria in the naturally fertilized region off the Kerguelen Islands

2015

View full text Add to dashboard Cite

show abstract

“…They respire most of the DOM taken up and convert the rest into bacterial biomass via growth (del Giorgio and Cole 2000). Bacterial growth in marine environments can be limited by several factors, such as temperature (Pomeroy and Deibel 1986;Kirchman and Rich 1997), DOM availability (Kirchman 1990;Kirchman and Rich 1997), inorganic nutrient availability (Cotner et al 1997), or micronutrients such as iron (Pakulski et al 1996;Church et al 2000).…”

mentioning

confidence: 99%

Response of bacterioplankton to iron fertilization in the Southern Ocean

Arrieta

Weinbauer

Lute

et al. 2004

Limnology & Oceanography

View full text Add to dashboard Cite

We studied the bacterial response to Fe fertilization over 3 weeks during the second iron-enrichment experiment (EisenEx) in the Southern Ocean. Bacterial abundance in the Fe-fertilized patch increased over the first 12 d following Fe release and remained about twice as high as outside the Fe-fertilized patch until the end of the experiment. Bacterial production peaked a few days after each of the three Fe releases inside the Fe-fertilized patch, reaching rates two to three times higher than outside the patch. Besides the peaks in leucine and thymidine incorporation following Fe release, bacterial production was not significantly higher inside the patch than outside, suggesting direct limitation of bacterial growth by Fe. Bacterial aminopeptidase activity roughly followed the increase in bacterial abundance, whereas cell-specific ␣-and ␤-glucosidase were higher inside the Fe-fertilized patch. The diversity of ␤-glucosidases was determined by capillary electrophoresis zymography. The different ␤-glucosidases showed much higher activity levels inside the patch than in the surrounding waters, and three additional ␤-glucosidases constituting ϳ55% of the total ␤-glucosidase activity were present inside the Fe-fertilized patch from day 9 onward. No major changes in response to Fe fertilization were detected in the phylogenetic composition of the bacterioplankton community, as determined by 16S rDNA fingerprinting, indicating a remarkable adaptation of the bacterioplankton community to episodic iron inputs. This stability on the phylogenetic level is contrasted by the dramatic qualitative and quantitative changes in ectoenzymatic activity.

show abstract

“…Fe has been shown to limit the growth of heterotrophic bacteria and phytoplankton in high nutrient-low chlorophyll (HNLC) regions (Coale et al 1996;Pakulski et al 1996) and certain coastal waters (Hutchins and Bruland 1998). It has been suggested that other metals, such as Zn and Co, could potentially limit the growth of certain phytoplankton species in open ocean environments (Morel et al 1994;Saito et al 2002).…”

mentioning

confidence: 99%

Element stoichiometries of individual plankton cells collected during the Southern Ocean Iron Experiment (SOFeX)

Twining

Baines

Fisher

2004

Limnology & Oceanography

182

181

View full text Add to dashboard Cite

During the Southern Ocean Iron Experiment (SOFeX), we analyzed Si, P, S, Mn, Ni, and Zn in individual diatoms, autotrophic flagellates, and heterotrophic flagellates with synchrotron-based X-ray fluorescence (SXRF) and calculated cellular C from measurements of cell size. Element stoichiometries for the different types of protists (normalized to either C, S, or P) were generally in good agreement with prior bulk analyses of natural assemblages but also revealed previously undocumented differences in elemental composition among cell types. Flagellated cells contained 39% more P than diatoms, which in turn contained 79% more Mn, 3-fold more Ni, and 2.6-fold more Zn than flagellates. Heterotroph cells contained approximately 40% more P and twice as much Zn as autotrophs. Manganese and Ni stoichiometries were negatively related to cell volume, while larger cells contained more Zn per mole C. Iron fertilization resulted in an approximate doubling of Mn, Ni, and Zn quotas and smaller increases in cellular P, but the timing of the stoichiometric changes varied between the two patches. Silicon contents of diatoms dropped approximately 40% after the first Fe addition but returned to prefertilization levels as cellular P doubled following the second addition, resulting in 40% lower Si : P ratios in the fertilized waters. The mean elemental stoichiometries calculated for all cells analyzed were comparable with previously published extended Redfield ratios for mixed plankton assemblages, but the observed differences between diatoms and flagellates and between autotrophs and heterotrophs indicate that valuable information is lost when all types of co-occurring plankton are grouped together for analysis.Metal biogeochemistry and ocean ecosystem function are closely linked. Several transition metals, including Mn, Fe, Co, Ni, Cu, and Zn, are required as cofactors for common proteins, and both heterotrophic and autotrophic protists accumulate these elements from the surrounding seawater, lowering dissolved concentrations in surface waters. Remineralization of these metals from sinking cells or zooplankton fecal pellets elevates their concentrations below the euphotic zone, resulting in the nutrient-like profiles commonly observed for these bioactive metals. Further, the availability and accumulation of trace metals can exert control over the biological functioning of the organisms. AcknowledgmentsThe authors gratefully acknowledge Michael Landry for providing the opportunity to participate in the SOFeX project and Chief Scientist Ken Johnson and the Captain and crew of the R/V Roger Revelle for enabling the collection of the samples. Jörg Maser, Stefan Vogt, and Dan Legnini provided invaluable technical assistance with the SXRF microprobe, and the manuscript benefited from discussions with Mark Brzezinski and the comments of two anonymous reviewers.

show abstract

Iron stimulation of Antarctic bacteria

Cited by 122 publications

References 10 publications

Fe and C co-limitation of heterotrophic bacteria in the naturally fertilized region off the Kerguelen Islands

Fe and C co-limitation of heterotrophic bacteria in the naturally fertilized region off the Kerguelen Islands

Response of bacterioplankton to iron fertilization in the Southern Ocean

Element stoichiometries of individual plankton cells collected during the Southern Ocean Iron Experiment (SOFeX)

Contact Info

Product

Resources

About