Southern Ocean iron enrichment experiment: carbon cycling in high- and low-Si waters.

Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, CA 95039-9647, USA.
Science (Impact Factor: 31.2). 05/2004; 304(5669):408-14. DOI: 10.1126/science.1089778
Source: PubMed

ABSTRACT The availability of iron is known to exert a controlling influence on biological productivity in surface waters over large areas of the ocean and may have been an important factor in the variation of the concentration of atmospheric carbon dioxide over glacial cycles. The effect of iron in the Southern Ocean is particularly important because of its large area and abundant nitrate, yet iron-enhanced growth of phytoplankton may be differentially expressed between waters with high silicic acid in the south and low silicic acid in the north, where diatom growth may be limited by both silicic acid and iron. Two mesoscale experiments, designed to investigate the effects of iron enrichment in regions with high and low concentrations of silicic acid, were performed in the Southern Ocean. These experiments demonstrate iron's pivotal role in controlling carbon uptake and regulating atmospheric partial pressure of carbon dioxide.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We quantified and compared physiological parameters and iron requirements of several oceanic Pseudo- nitzschia spp., newly isolated from the high-nitrate, low-chlorophyll waters of the northeast subarctic Pacific, with coastal Pseudo-nitzschia spp. and the oceanic centric diatom Thalassiosira oceanica at a range of iron concentrations. In iron-replete conditions, the iron (Fe) : carbon (C) ratios in the six Pseudo-nitzschia isolates ranged from 157 mmol Fe mol C21 to 248 mmol Fe mol C21, with no apparent differences between oceanic and coastal isolates. In low iron conditions, all Pseudo-nitzschia spp. exhibited marked reductions in photosynthetic efficiency, whereas the extent of the reductions in specific growth rates varied among species. When iron-limited, the Fe : C ratios decreased significantly in all oceanic Pseudo-nitzschia species, with the lowest ratios ranging from 2.8 mmol Fe mol C21 to 3.7 mmol Fe mol C21. Combined with faster growth rates, lower Fe : C ratios in oceanic isolates of Pseudo-nitzschia resulted in significantly higher iron-use efficiencies relative to their coastal congeners and T. oceanica. The wide range between iron-replete (Fe-Qhigh) and iron-limited (Fe-Qlow) quotas indicates that oceanic Pseudo-nitzschia spp. have an extensive plasticity in iron contents relative to other diatoms grown at similar iron concentrations reported in the literature; the Fe-Qhigh : Fe-Qlow ratios for oceanic species were 46 to 67, whereas for coastal Pseudo-nitzschia species they were 16 and 43. We suggest that the ability of oceanic Pseudo-nitzschia species to exhibit an extensive growth response to iron enrichment events may, in part, be a result of their extraordinary capacity to accumulate and potentially store large amounts of intracellular iron when iron concentrations are high, yet substantially reduce their iron requirements to sustain fast growth rates well after external iron concentrations are depleted.
    Limnology and Oceanography 01/2006; 51(5):2092-2101. · 3.62 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
    Chemical Reviews 03/2007; 107(2):308-41. · 41.30 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Culture of the oil-degrading marine bacterium Marinobacter hydrocarbonoclasticus gave the known siderophore petrobactin (1) and the new metabolite petrobactin sulfonate (2), the first marine siderophore containing a sulfonated 3,4-dihydroxy aromatic ring. The structure of petrobactin sulfonate was elucidated from spectral data, resulting in a revision of the NMR assignments of petrobactin.
    Journal of Natural Products 12/2004; 67(11):1897-9. · 3.29 Impact Factor

Full-text (5 Sources)

Available from
Jun 2, 2014

View other sources