Title Bioavailability of organically bound Fe to model phytoplankton of the Southern Ocean
Author Hassler, C.S.; Schoemann, V.
Author Affil Hassler, C.S., Centre for Australian Weather and Climate Research (CAWCR), Hobart, Tasmania, Australia. Other: Université Libre de Bruxelles, Belgium
Source Biogeosciences, 6(10), p.2281-2296. Publisher: Copernicus GmbH on behalf of the European Union, Katlenburg-Lindau, International. ISSN: 1726- 4170
Publication Date 2009
Notes In English. Part of special issue no. 46, Iron biogeochemistry across marine systems at changing times, edited by Turner, D., Hunter, K., and Riebesell, U., http://www.biogeosciences.net/special_issue46.h tml; includes supplement, http://www.biogeosciences.net/6/2281/2009/bg- 6-2281-2009-supplement.pdf; published in Biogeosciences Discussions: 4 February 2009, http://www.biogeosciences- discuss.net/6/1677/2009/bgd-6-1677-2009.html; accessed in Feb., 2011; abstract: doi:10.5194/bg-6-2281-2009. 89 refs. GeoRef Acc. No: 310152. CRREL Acc. No: 65006701
Index Terms algae; diffusion; liquid phases; metals; plankton; solubility; Southern Ocean; bioaccumulation; bioavailability; biochemistry; carbon; catecholate siderophore; climate effects; diatoms; iron; ligands; liquid phase; living taxa; microorganisms; nutrients; organic compounds; phytoplankton; pigments; Plantae; porphyrins; reactivity; saccharides; sea water
Abstract Iron (Fe) is known to be mostly bound to organic ligands and to limit primary productivity in the Southern Ocean. It is thus important to investigate the bioavailability of organically bound Fe. In this study, we used four phytoplankton species of the Southern Ocean (Phaeocystis sp., Chaetoceros sp., Fragilariopsis kerguelensis and Thalassiosira antarctica Comber) to measure the influence of various organic ligands on Fe solubility and bioavailability. Short-term uptake Fe:C ratios were inversely related to the surface area to volume ratios of the phytoplankton. The ratio of extracellular to intracellular Fe is used to discuss the relative importance of diffusive supply and uptake to control Fe bioavailability. The effect of excess organic ligands on Fe bioavailability cannot be solely explained by their effect on Fe solubility. For most strains studied, the bioavailability of Fe can be enhanced relative to inorganic Fe in the presence of porphyrin, catecholate siderophore and saccharides whereas it was decreased in presence of hydroxamate siderophore and organic amine. For Thalassiosira, iron bioavailability was not affected by the presence of porphyrin, catecholate siderophore and saccharides. The enhancement of Fe bioavailability in presence of saccharides is presented as the result from both the formation of bioavailable (or chemically labile) organic form of Fe and the stabilisation of Fe within the dissolved phase. Given the ubiquitous presence of saccharides in the ocean, these compounds might represent an important factor to control the basal level of soluble and bioavailable Fe. Results show that the use of model phytoplankton is promising to improve mechanistic understanding of Fe bioavailability and primary productivity in HNLC regions of the ocean.
URL http://www.biogeosciences.net/6/2281/2009/bg-6-2281-2009.pdf
Publication Type journal article
Record ID 91452