Iron bioavailability to phytoplankton: an empirical approach
In: The ISME Journal: Multidisciplinary Journal of Microbial Ecology. Nature Publishing Group: London. ISSN 1751-7362; e-ISSN 1751-7370, more |   |
| Keywords | Marine Sciences
Marine Sciences > Marine Sciences General
Scientific Community
Scientific Publication
Marine/Coastal |
| Project | Top | Authors | - Association of European marine biological laboratories, more
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| Authors | | Top | - Lis, H.
- Shaked, Y.
- Kranzler, C.
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| Abstract | Phytoplankton are often limited by iron in aquatic environments. Here we examine Fe bioavailability to phytoplankton by analyzing iron uptake from various Fe substrates by several species of phytoplankton grown under conditions of Fe limitation and comparing the measured uptake rate constants (Fe uptake rate/substrate concentration). When unchelated iron, Fe', buffered by an excess of the chelating agent EDTA is used as the Fe substrate, the uptake rate constants of all the eukaryotic phytoplankton species are tightly correlated and proportional to their respective surface areas (S.A.). The same is true when FeDFB is the substrate, but the corresponding uptake constants are one thousand times smaller than for Fe'. The uptake rate constants for the other substrates we examined fall mostly between the values for Fe' and FeDFB for the same S.A. These two model substrates thus empirically define a bioavailability envelope with Fe' at the upper and FeDFB at the lower limit of iron bioavailability. This envelope provides a convenient framework to compare the relative bioavailabilities of various Fe substrates to eukaryotic phytoplankton and the Fe uptake abilities of different phytoplankton species. Compared with eukaryotic species, cyanobacteria have similar uptake constants for Fe' but lower ones for FeDFB. The unique relationship between the uptake rate constants and the S.A. of phytoplankton species suggests that the uptake rate constant of Fe-limited phytoplankton has reached a universal upper limit and provides insight into the underlying uptake mechanism. |
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