Aquatic Sciences Meeting, Albuquerque 2001
| SS16 Iron Bioavailability and Limitation to Primary Production (Disciplinary Connections) |
| Date: Monday, February 12, 2001, Time: 4:30:00 PM |
| Location: Mesilla |
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| Eldridge, M, L, The University of Tennessee, Knoxville, USA, eldrid00@utk.edu |
| Trick, C, G, The University of Western Ontario, London, Canada, cyano@julian.uwo.ca |
| Alm, M, B, Grice Marine Lab, University of Charleston, Charleston, USA, |
| DiTullio, G, R, Grice Marine Lab, University of Charleston, Charleston, USA, ditullioj@cofc.edu |
| Wilhelm, S, W, University of Tennessee, Knoxville, USA, wilhelm@utk.edu |
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| INFLUENCE OF IRON AVAILABILITY ON GROUP-SPECIFIC PHYTOPLANKTON SUCCESS IN HNLC WATERS OF THE SUBTROPICAL PACIFIC OCEAN |
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| Studies in HNLC waters suggest that increased Fe availability results in an increase in phytoplankton biomass. To more closely examine this, we monitored the response of individual groups of phytoplankton (large eukaryotes, picoeukaryotes and cyanobacteria) to small additions and reductions in available Fe (+0.5 to +2.5 nM Fe, and -1.0 to -5.0 nM Fe via addition of the fungal siderophore desferrioxamine-B) in regions along the coast of Peru where Fe concentrations are less than 100 pM. While bulk measurements of chlorophyll demonstrated an increase in biomass in +Fe treatments, flow cytometric analysis demonstrated that this was due to increases in the abundance of iron-starved large eukaryotes (to ca 180% ambient). In contrast, picoeukaryotes increased cell abundance with decreasing Fe availability (ca 167%), although chlorophyll per cell responded in an inverse manner. Cyanobacterial abundance increased (ca 160 %) and decreased (ca 30 %) linearly in abundance with Fe availability, suggesting they are iron-limited but not iron-starved. The results demonstrate that members of the marine phytoplankton community respond differently to Fe availability, stressing the role of biological competition among organisms in Fe-limited environments. |
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