Aquatic Sciences Meeting, Albuquerque 2001
| SS16 Iron Bioavailability and Limitation to Primary Production (Disciplinary Connections) |
| Date: Monday, February 12, 2001, Time: 4:15:00 PM |
| Location: Mesilla |
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| Tremblay, J, E, McGill University, Montreal, Canada, jett@globetrotter.qc.ca |
| Bucciarelli, E, , UMR CNRS, Brest, France, Eva.Bucciarelli@univ-brest.fr |
| Van der Wagt, B, , NIOZ, Texel, Netherlands, Wagt@nioz.nl |
| de Baar, H, J, NIOZ, Texel, Netherlands, debaar@nioz.nl |
| Price, N, M, McGill University, Montreal, Canada, NPRICE@BIO1.lan.mcgill.ca |
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| EFFECT OF IRON ON THE C/N/P/Si COMPOSITION OF DIATOMS, A PARTIAL SYNTHESIS |
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| An increasing number of studies report deviations in the Redfield ratios of marine diatoms as a function of Fe nutrition state. A partial synthesis of recent laboratory results shows that the nature and strength of the deviations vary greatly among species. The most common response is a decrease in the N/P and C/P ratios under Fe-limited growth. The C/N ratio remains relatively constant over a range of Fe concentrations, but some notable exceptions exist in which the ratio decreases strongly with low Fe, suggesting that at least two types of response are possible. Substantial increases in Si/C and Si/N ratios are generally the norm for Fe-limited diatoms, but in some species the ratios are nearly invariant with Fe. The apparent dichotomy in behaviour of the C/N, Si/C and Si/N ratios suggests the existence of distinct diatom ecotypes, which have different consequences for elemental fluxes under Fe limitation. Although most of the evidence gathered thus far is empirical, it points toward research avenues aimed at elucidating the underlying physiology. The data also suggest caution in parametrizing biogeochemical models across ecosystems. The unfortunate lack of field data available for comparison with culture work on N/P and C/P ratios could be remedied by including measurements of particulate organic phosphorus in future sampling programs. |
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