Change in the concentrations of iron in different size fractions during growth of the oceanic diatom Chaetoceros sp.: importance of small colloidal iron

Citation
J. Nishioka et S. Takeda, Change in the concentrations of iron in different size fractions during growth of the oceanic diatom Chaetoceros sp.: importance of small colloidal iron, MARINE BIOL, 137(2), 2000, pp. 231-238
Citations number
41
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Aquatic Sciences
Journal title
MARINE BIOLOGY
ISSN journal
0025-3162 → ACNP
Volume
137
Issue
2
Year of publication
2000
Pages
231 - 238
Database
ISI
SICI code
0025-3162(200009)137:2<231:CITCOI>2.0.ZU;2-5
Abstract
Laboratory culture experiments were performed to study the changes in size- fractionated Fe concentrations during the growth of the oceanic diatom Chae toceros sp. Fe concentration was estimated for three size fractions: large labile particles (>0.2 mu m), small colloidal particles (0.2 mu m to 200 kD a) and soluble species (<200 kDa). The size-fractionated Fe concentration i n the nutrient-enriched filtered seawater medium without diatom cells becam e stable within 4 d after the spike of FeCl3 solution. Light irradiation by white fluorescent tubes with a 14 h light:10 h dark cycle did not signific antly alter concentrations of the size-fractionated Fe. For the phytoplankt on culture experiment, Fe-starved diatom cells were inoculated into the nut rient-enriched media aged for 19 d after the addition of FeCl3. With the gr owth of diatom cells, total acid-labile Fe concentrations decreased from 0. 60 to 0.46 nM during 7 d of incubation. However, only the concentration of the small colloidal particles showed a significant decrease; the concentrat ion of the other size fractions remained relatively constant. Although the media still contained sufficient amounts Fe as large labile particles and s oluble species, diatom cells appeared to be Fe-limited once Fe as small col loidal particles had been used up. These results suggest that Fe in the sma ll colloidal particle fraction was the most dynamic size fraction during th e growth of the diatom Chaetoceros sp. In addition, to better understand Fe dynamics in the ocean, we must consider the influence of phytoplankton gro wth on small colloidal Fe [which is typically included in the dissolved Fe fraction (<0.2 mu m)].