Aquatic Sciences Meeting, Albuquerque 2001
| CS39 Trace Metal Limitation of Biogeochemistry |
| Date: Tuesday, February 13, 2001, Time: 10:45:00 AM |
| Location: Dona Ana |
| Trick, C, G, Department of Plant Sciences, University of Western Ontario, London, Ontario, Canada, cyano@julian.uwo.ca |
| DiTullio, G, R, University of Charleston, Grice Marine Laboratory, Charleston, SC, USA, ditullioj@cofc.edu |
| Hutchins, D, A, College of Marine Studies, University of Delaware, Lewes, DE, USA, dahutch@udel.edu |
| Weaver, R, S, College of Marine Studies, University of Delaware, Lewes, DE, USA, rsweaver@udel.edu |
| Wilhelm, S, W, Department of Microbiology, University of Tennessee, Knoxville, TN, USA, wilhelm@utk.edu |
| EFFECTS OF ARTIFICIAL CHELATORS ON PHYTOPLANKTON COMMUNITY STRUCTURE IN THE OLIGOTROPHIC SUBTROPICAL PACIFIC |
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| Although it has been demonstrated that the bioavailability of iron is tightly coupled to the presence of iron-chelating ligands in seawater, it remains to be determined if the character of these ligands affects iron assimilation. To gain insight on this, we carried out experiments in the oligotrophic subtropical Pacific Ocean, using the fungal siderophores desferoxamine B and rhodotorulic acid to manipulate the source of iron to the iron-limited community. Experiments at concentrations ranging from 1-100 nM demonstrate a concentration dependent response to these siderophores, with low concentrations enhancing the growth and increasing concentrations repressing growth, depending on the choice of ligand. Cell abundance, growth rate, fluorescence characteristics, species diversity, sinking rate estimates and flow cytometry data provide information demonstrating that the populations primary response occurred at the level of cellular physiology (reduction in photosynthetic efficacy, reduction in cellular chlorophyll, reduced community sinking rates). We demonstrate that bulk community properties (e.g., total chlorophyll) may provide incomplete information regarding the response of the community to a perturbation and the addition of xeno-ligands may have unexpected alterations in naturally iron-limited populations. |
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