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| Corn, M; Belviso, S; Nival, P; Vigot, A; Buatmenard, P. |
| We report results from free-drifting sediment trap deployments at 200 m depth which enable measurement of the diel variations in the downward flux of detrital particulate dimethylsulphoniopropionate (DMSPp) over periods of 24-72 hours in three contrasting trophic regimes of the tropical northeastern Atlantic Ocean off Mauritania. The source of DMSPp was the phytoplankton living in surficial water layers. The three regimes exhibited similar strong diel cycles, the nocturnal fluxes being up to 100-fold lower than the daytime fluxes. High (or low) detrital DMSPp, fluxes were associated with high (or low) numbers of pteropods trapped inside the sampling cups. Thus, contamination of sinking material is likely to have occurred, promoting an overestimate of the... |
| Tipo: Text |
Palavras-chave: SULFUR; DMS; DMSP; ZOOPLANKTON; SEDIMENTATION. |
| Ano: 1994 |
URL: http://archimer.ifremer.fr/doc/00098/20886/18500.pdf |
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| Marty, D; Nival, P; Yoon, Wd. |
| During the ''Eumeli-4'' cruise in the northeastern tropical Atlantic Ocean, the occurrence and activity of methanoarchaea in the water column were examined, whether in association with sinking particulate material collected by means of sediment traps and in situ pumps, or with zooplankton organisms harvested with plankton nets and their freshly egested fecal pellets. Besides highlighting the necessity to use adequate particle samplers, the results confirm the presence of Viable pelagic methanogens in particulates; likely to be present in zooplankton, in the form of enteric flora, these archaea would be released in the sea water column within egested fecal pellets. |
| Tipo: Text |
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| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00093/20449/18121.pdf |
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| Andersen, V; Nival, P. |
| A simplified model of the pelagic ecosystem of the coastal surface waters (0 to 20 m) of the Ligurian Sea (Mediterranean) is described. Phytoplankton, copepods, salps, chaetognaths, dissolved inorganic nitrogen and particulate organic matter are considered. The system is open (winter input of deep nutrients and sedimentation of particulate organic matter) and is influenced by temperature and irradiance. This model simulates the typical annual variation of the plankton in the considered area. Nevertheless, a simulation during five years shows that, in contrast with the other state variables, salps and chaetognaths have an unstable behaviour. We assume that these organisms migrate in the superficial waters. |
| Tipo: Text |
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| Ano: 1988 |
URL: http://archimer.ifremer.fr/doc/00267/37815/35896.pdf |
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| Minas, Hj; Minas, M; Coste, B; Gostan, J; Nival, P; Bonin, M P. |
| Apparent nutrient consumption and oxygen production, representing net community production, appear among other methods to offer a valuable approach to new production. Net community production determinations were carried out a long time ago in the Mediterranean Sea, with the idea of comparing them with super(14)C-productivity measurements. Our main objective here is to summarize the results of these studies and to review them in relation to the latest discussions concerning productivity of the Sargasso Sea. In the main oligotrophic coastal waters of the Ligurian Sea, there is no evidence for positive net production in the subsurface oxygen maximum associated with the summer thermocline (Minas, Coste, 1964), and Reid's (1962) physical explanation of the... |
| Tipo: Text |
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| Ano: 1988 |
URL: http://archimer.ifremer.fr/doc/00267/37833/35914.pdf |
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| Schmidt, S; Nival, P; Reyss, Jl; Baker, M; Buatmenard, P. |
| Dissolved and particulate Th-234 activities were determined and phyto- and zooplankton biomass were periodically measured 8 miles off Nice (Mediterranean Sea) during spring 1987. The results show a strong variability of Th-234 distribution on short time scales in northwestern Mediterranean surface waters. The good correlation observed between the zooplankton biomass and the rate of Th-234 export to deep water in particulate form is in agreement with the assumption that the residence time of particulate Th-234 in oceanic surface waters is controlled by zooplankton grazing. Moreover, our results indicate the importance of salps in particular as efficient removers of small suspended particles in surface waters. |
| Tipo: Text |
Palavras-chave: TH-234; ZOOPLANKTON; SCAVENGING; PARTICLE FLUX. |
| Ano: 1992 |
URL: http://archimer.ifremer.fr/doc/00100/21155/18774.pdf |
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