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| Format: | Dataset Open Access |
| Language: | en |
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PANGAEA
2001
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| Online Access: | https://doi.org/10.1594/PANGAEA.787696 |
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| _version_ | 1867168823396794368 |
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| author | Leynaert, Aude Tréguer, Paul Lancelot, Christiane Rodier, Martine |
| author_facet | Leynaert, Aude Tréguer, Paul Lancelot, Christiane Rodier, Martine |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | During the EBENE cruise (November 1996), distributions of biogenic silica concentration and production rates were investigated in the surface waters of the equatorial Pacific (180°W, from 8°S to 8°N), with particular emphasis on the limitation of the biogenic silica production by ambient silicic acid concentrations. Integrated over the depth of the euphotic layer, concentrations of biogenic silica and production rates were maximum at the Equator (8.0 and 2.6 mmol/m**2/d) and decreased more or less symmetrically polewards. Contribution of diatoms to the new production was estimated indirectly, comparing biogenic silica production rates and available data of new and export production in the same area. This comparison shows that new production in the equatorial area could mostly be sustained by diatoms, accounting for the major part of the exported flux of organic carbon. Kinetics experiments of silicic acid enrichment were performed. Half saturation constants were 1.57 µM at 3°S and 2.42 µM at the Equator close to the ambient concentrations. The corresponding Vmax values for Si uptake were 0.028/h at 3°S and 0.052/h at the equator. Experiments also show that in situ rates were restricted to 13-78% of Vmax, depending on ambient silicic acid concentrations. This work provides the first direct evidence that the rate of Si uptake by diatom populations of the equatorial Pacific is limited by the ambient concentration of silicic acid. However, such Si limitation might not be sufficient in itself to explain the low diatom growth rates observed, and additional limitation is suggested. One hypothesis that is consistent with the results of Fe limitation studies is that Fe and Si limitations may interact, rather than just being a mutually exclusive explanation for the HNLC character of the system. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_787696 |
| institution | PANGAEA |
| language | en |
| publishDate | 2001 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Production of biogenic silica during the EBENE cruise, Equatorial Pacific Leynaert, Aude Tréguer, Paul Lancelot, Christiane Rodier, Martine Biogenic silica; Biogenic silica concentration (Ragueneau & Tréguer 1994); Biogenic silica production (Leynaert et al 1996 in Baeyens et al.); Biogeochemical Processes in the Oceans and Fluxes; CTD/Rosette; CTD-RO; Date/Time of event; DEPTH, water; Dissolved silica, colorimetric (Parsons et al., 1984, Pergamon Press, Oxford); EBENE; EBENE_001; EBENE_002; EBENE_003; EBENE_004; EBENE_005; EBENE_034; EBENE_057; EBENE_073; EBENE_074; EBENE_090; EBENE_133; EBENE_140; EBENE_141; EBENE_142; EBENE_143; EBENE_144; EBENE_145; EBENE_146; EBENE_147; Elevation of event; Equatorial Pacific; Event label; JGOFS; Joint Global Ocean Flux Study; L Atalante; Latitude of event; Longitude of event; Production of biogenic silica; PROOF; Silicate; Silicic acid uptake rate, specific; Silicon Cycling in the World Ocean; SINOPS During the EBENE cruise (November 1996), distributions of biogenic silica concentration and production rates were investigated in the surface waters of the equatorial Pacific (180°W, from 8°S to 8°N), with particular emphasis on the limitation of the biogenic silica production by ambient silicic acid concentrations. Integrated over the depth of the euphotic layer, concentrations of biogenic silica and production rates were maximum at the Equator (8.0 and 2.6 mmol/m**2/d) and decreased more or less symmetrically polewards. Contribution of diatoms to the new production was estimated indirectly, comparing biogenic silica production rates and available data of new and export production in the same area. This comparison shows that new production in the equatorial area could mostly be sustained by diatoms, accounting for the major part of the exported flux of organic carbon. Kinetics experiments of silicic acid enrichment were performed. Half saturation constants were 1.57 µM at 3°S and 2.42 µM at the Equator close to the ambient concentrations. The corresponding Vmax values for Si uptake were 0.028/h at 3°S and 0.052/h at the equator. Experiments also show that in situ rates were restricted to 13-78% of Vmax, depending on ambient silicic acid concentrations. This work provides the first direct evidence that the rate of Si uptake by diatom populations of the equatorial Pacific is limited by the ambient concentration of silicic acid. However, such Si limitation might not be sufficient in itself to explain the low diatom growth rates observed, and additional limitation is suggested. One hypothesis that is consistent with the results of Fe limitation studies is that Fe and Si limitations may interact, rather than just being a mutually exclusive explanation for the HNLC character of the system. |
| title | Production of biogenic silica during the EBENE cruise, Equatorial Pacific |
| topic | Biogenic silica; Biogenic silica concentration (Ragueneau & Tréguer 1994); Biogenic silica production (Leynaert et al 1996 in Baeyens et al.); Biogeochemical Processes in the Oceans and Fluxes; CTD/Rosette; CTD-RO; Date/Time of event; DEPTH, water; Dissolved silica, colorimetric (Parsons et al., 1984, Pergamon Press, Oxford); EBENE; EBENE_001; EBENE_002; EBENE_003; EBENE_004; EBENE_005; EBENE_034; EBENE_057; EBENE_073; EBENE_074; EBENE_090; EBENE_133; EBENE_140; EBENE_141; EBENE_142; EBENE_143; EBENE_144; EBENE_145; EBENE_146; EBENE_147; Elevation of event; Equatorial Pacific; Event label; JGOFS; Joint Global Ocean Flux Study; L Atalante; Latitude of event; Longitude of event; Production of biogenic silica; PROOF; Silicate; Silicic acid uptake rate, specific; Silicon Cycling in the World Ocean; SINOPS |
| url | https://doi.org/10.1594/PANGAEA.787696 |