PROSOPE - GROUP
Sept. 4 -> Oct. 4, 1999
La Thalassa
H. CLAUSTRE : head of mission and project leader
ORIGINE, OBJECTIVES
The founding of the PROSOPE (PROductivity of Oceanic Pelagic System) group in 1997 was based upon a number of observations related to the initial aims and the results of the JGOFS program. To fit with the final objective of modeling the carbon cycle at a global scale, the JGOFS program selected a limited number of variables and processes which had to be documented (core parameters) in certain "representative" biogeochemical provinces. This compromise strategy, although best adapted in a global context, was necessarily simplifying: some variables, processes or critical scale may therefore have been neglected, not being initially quoted as essential. Recent studies, even including some which were conducted under JGOFS, have indeed demonstrated that if the "core parameter strategy" is necessary, it is not sufficient in many cases.
As part of the PROOF (former JGOFS-France) program, the main objective of the PROSOPE group, a multidisciplinary community of more than 40 scientists (see list of participants), is to focus a large part of its activity on specific and detailed studies related to the carbon cycle which were not taken into consideration by the former global strategy of JGOFS. The group has a variety of competencies which range from molecular approaches of phytoplankton taxonomy to biogeochemical applications of ocean color remote sensing. Many of the members of the group were involved in the previous operations of the JGOFS-France program and, in particular, those devoted to the study of oligotrophic systems (North Atlantic and South Pacific Gyres in the context of EUMELI and OLIPAC programs, respectively). To reach its objective, the group activity is organized over three interactive levels.
Level 1 : The exploitation of databases. The analysis of existing databases is carried out in two main directions. Firstly, to infer generic parameterizations which are required for modelisation at a global scale. Secondly, to identify specific processes, variables or scales which would require increasing attention within carbon cycle studies. An example of this two-directional exploitation of databases is given by the analysis of the relationship between the particle scattering coefficient and chlorophyll a concentration. At a global scale, a non-linear relationship can be established between both variables (analysis of more than 2500 data, Loisel and Morel 1998, Limnol. Oceanogr., 43, 847-858). This relationship, however, presents a significant "biological noise". Part of this noise can be attributed to variations in the particle scattering coefficient at a daily scale (e.g. Claustre et al., 1999, JGR, 104, 3401-3422), a scale which is generally neglected (for both conceptual and methodological reasons) in biogeochemical studies.
Level 2 : The development of new methodology. Three main areas of research have been identified. (1) The development of methods allowing a better understanding of biogenic elemental fluxes. This includes new techniques applied to the simultaneous determination of DOC, NOD and POD as well as isotopic techniques for the estimation of phosphorus fluxes in dissolved and particulate phases. (2) The use and the validation of new types of optical profilers for the quantification of biogeochemically-relevant optical quantities in a quasi-continuous mode. This allows small scale biogeochemical studies to be carried out. (3) The use of methods in molecular biology for the study of phytoplankton diversity. In particular, members of the group have contributed to the identification a new phytoplankton class, the bolidophyceae (Guillou et al., 1999, J. Phycol., 35, 368-381) and have compared various approaches (taxonomic pigments vs molecular probes) in quantifying the in situ specific phytoplankton biomass (Moon-van der Staay et al., 2000, Limnol. Oceanogr., 45, 99-109).
Level 3. Sea-going activities. The in situ observation conducted by the scientists typically fit with the objective defined by JGOFS/SCOR in 1990: "in various representative ocean regimes", process studies have to be conducted "to assess the rates of, and controls on, vertically distributed primary production and the degree to which they can be determined using remotely-sensed near-surface pigment data". At the same time, the proposed studies have the ambition to take advantage of research conducted at levels 1 and 2. Therefore, the first cruise of the group in autumn 1999 had four main objectives (see also overall description of the PROSOPE cruise):
To carry out classical process studies, typical of JGOFS To focus on the small scale biogeochemical processes, particularly at a daily scale. To study the influence of nitrogen, phosphorus and iron on oceanic fertility. To conduct calibration/validation operations for the SeaWiFS color sensor
PARTICIPANTS
NOM (lieu d'origine) |
STATUT |
SPECIALITE |
Temps (%) |
| Antoine D. (Villefranche) | CR CNRS | optique marine et atmosphérique | 10 |
| Babin M. (Villefranche) | CR CNRS | photosynthèse marine, optique | 20 |
| Belviso S. (Gif/Yvette) | CR CNRS | produits soufrés | 10 |
| Begovic M. (Villefranche) | Thésitif | pC02 en Méditerranée | 30 |
| Bianchi M. (Marseille) | DR CNRS | microbiologie/réseau microbien | 25 |
| Blanchot J. (Roscoff) | CR IRD | cytométrie, fixation N2 | 30 |
| Bricaud A. (Villefranche) | DR CNRS | optique, biooptique | 10 |
| Bruyant F. (Villefranche) | Thésitif | photosynthèse marine, fluorescence variable | 30 |
| Carlotti F. (Arcachon) | CR CNRS | mesozooplancton, OPC | 10 |
| Claustre H. (Villefranche) | CR CNRS | biogéochimie, pigments, biooptique | 40 |
| Conan P. (Marseille) | MC, Marseille | production primaire | 15 |
| Copin C. (Villefranche) | CR CNRS | gaz dissous, alcalinité, pH | 10 |
| Dolan J. (Villefranche) | CR CNRS | biomasse et rôle des ciliés | 10 |
| Garczarek L. (Roscoff) | Thésitif | Biologie moléculaire | 30 |
| Guieu C. (Paris) | CR CNRS | éléments métalliques traces/aérosols | 20 |
| Guillou L. (Roscoff) | Post-doc | taxonomie moléculaire | 30 |
| Goutx M. (Marseille) | CR CNRS | marqueurs organiques | 10 |
| Gorsky G. (Villefranche) | CR CNRS | particules en suspension, macroplancton | 10 |
| Jacquet S. (Roscoff) | Thésitif | cytométrie, cycles | 50 |
| Lanoiselé J. (Paris) | ITA, CNRS | flux air-mer de CO2 - bouée CARIOCA | 20 |
| Lantoine F. (Banyuls) | MC, Paris VI | phycobilines, influence du fer | 20 |
| Leblanc K. 5marseille) | Thésitif | Cycle silice Méditerranée | 50 |
| Leblond N. (Villefranche) | ITA, CNRS | Gestion des trappes | 10 |
| Lefèvre D. (Marseille) | CR CNRS | Production communautaire | 15 |
| Marie D. (Roscoff) | ITA, CNRS | cytométrie | 30 |
| Malara.G. (Villefranche) | ITA, CNRS | automatisation HIAC | 50 |
| Marty J.C. (Villefranche) | DR CNRS | Biogéochimie, marqueurs organiques | 10 |
| Merlivat L. (Paris) | DR CNRS | flux air-mer de CO2 - bouée CARIOCA | 5 |
| Migon C. (Villefranche) | MC, Corte | éléments métalliques traces/aérosols | 15 |
| Momzikoff A. (Paris) | CR CNRS | matière organique dissoute totale et colorée | 20 |
| Morel A. (Villefranche) | Pr, Paris VI | optique marine et atmosphérique | 10 |
| Moutin T. (Marseille) | MC | cycle du phosphore | 30 |
| Nicolas E. (Villefranche) | IR, CNRS | éléments métalliques traces | 10 |
| Oubelkheir K. (Villefranche) | thésitif | capteurs optiques et biogéochimie | 20 |
| Panagiopoulos (Marseille) | thésitif | MOD, bactéries | 40 |
| Partensky F. (Roscoff) | CR CNRS | cytométrie, biologie moléculaire | 30 |
| Picheral M. (Villefranche) | ITA, CNRS | Profileur Vidéo Marin | 20 |
| Quéguiner B. (Brest) | PR, Marseille | silice et phytoplancton | 10 |
| Raimbault P. (Marseille) | DR CNRS | sels nutritifs | 10 |
| Ras Joséphine(Villefranche) | CDD | Traitement données, pigments | 50 |
| Ridame, C. (Villefranche) | Thésitif | cycle du phosphore, aérosols sahariens | 50 |
| Sciandra A. (Villefranche) | CR CNRS | concentration et spectre de taille des particules | 30 |
| Sempéré R. (Marseille) | CR CNRS | matière organique dissoute | 20 |
| Simon N. (Roscoff) | MC, Paris VI | biologie moléculaire, picoplancton | 30 |
| Taillez D. (Villefranche) | ITA CNRS | acquisition CTD + traitement | 30 |
| Van Wanbecke F. (Marseille) | CR CNRS | relations bactéries-phytoplancton | 20 |
| Vaulot D. (Roscoff) | DR CNRS | picoplancton, biologie moléculaire | 30 |
REFERENCES
| Data base exploitation | Small scale studies | Phosphorus cycle |
| Methods | Molecular tools |
Bricaud A., Morel A., Babin M., Allali K. and H. Claustre, 1998. Variations of light absorption by suspended particles with the chlorophyll a concentration in oceanic (Case 1) waters : analysis and implications for bio-optical models. Journal of Geophysical Research, 103, 31,033-31,034.
Loisel H. and A. Morel, 1998. Light scattering and chlorophyll concentration in case I waters : a re-examination. Limnology and Oceanography, 43, 847-858.
Partensky F, Blanchot J. and D. Vaulot, 1998. Differential distribution of Prochlorococcus and Synechococcus in oceanic waters: a review. In: Charpy L, Larkum H. (eds). (eds). Marine cyanobacteria and related organisms. Bull. Inst. Océanogr., Monaco, Numéro spécial 19, 431-449.
Partensky F, Hess W.R. and D. Vaulot, 1998. Prochlorococcus, a marine photosynthetic prokaryote of global significance. Microbiology and Molecular Biology Reviews, 63, 106-127.
Small scale studies (including diurnal cycles)
Claustre H., Morel A., Babin M., Cailliau C., Marie D., Marty J.-C., Taillez D. and D. Vaulot, 1999. Variability in particle attenuation and chlorophyll fluorescence in the tropical Pacific : scales, patterns and some biogeochemical implications. Journal of Geophysical Research, 104, 3401-3422.
Claustre, H., Fell, F., Oubelkheir, K., Prieur, L., B. Gentilli, Sciandra, A. and M. Babin (2000). Continuous monitoring of surface optical properties across a geostrophic front: biogeochemical inferences. Limnology and Oceanography, 45, in press.
Jacquet S., Lennon, J.-F., Marie D., and D. Vaulot, 1998. Picoplankton population dynamics in coastal waters of the NW Mediterranean Sea. Limnology and Oceanography, 43, 1916-1931.
Liu H.B., Landry M., Campbell L. and D. Vaulot, 1998. Prochlorococcus growth rates in the central equatorial Pacific: an application of the fmax approach. Journal of Geophysical Research, 104, 3391-3399.
Vaulot D. and D. Marie, 1998. Diel variability of photosynthetic picoplankton equatorial Pacific. Journal of Geophysical Research, 104, 3297-3310.
Migon C., Sandroni V., and G. Copin-Montégut, 1998, Phosphates in rainwaters : total fluxes and partitioning between labile and refractory phases. Annales Geophysicae, 16, 2, C 733.
Migon C. and Sandroni, V. 1998. Phosphorus in rainwaters : partitioning, inputs and impact on the marine upper layer. Limnology and Oceanography, 44, 1160-1165.
Brusaard C.P.D., Marie D., and G. Bratbak, 2000. Flow cytometric detection of viruses. Journal of Virological Methods, in press.
Brussaard C.P.D., Thyrhaug R., Marie D., and G. Bratbak, 1999. Flow cytometric analyses of virus infection in two marine phytoplankton species, Micromonas pusilla (Prasinophyceae) and Phaeocystis pouchetii (Prymnesiophyceae). Journal of Phycology 35, 941-948.
Jacquet S., Lennon J.-F. and D. Vaulot, 1997. Application of a compact automatic sea water to high frequency picoplankton studies. Aquatic Microbial Ecology, 14, 309-314.
Marie D., Brussaard C.P.D., Thyrhaug R., Bratbak G. and D. Vaulot, 1998. Enumeration of viruses in marine samples by flow cytometry. Applied and Environmental Microbiology, 65, 45-52.
Marie D., Partensky. F., Simon N., Guillou L. and D. Vaulot, 2000. Flow cytometry analysis of marine picoplankton. In: Diamond R.A., DeMaggio S. (ed.). In Living Colors: Protocols in Cytometry and Cell sorting. R.G. Landes Company., in press.
Molecular tools for the characterization of new groups
Guillou L., Chrétiennot-Dinet M-J, Medlin L.K., Claustre H., Loiseaux-de Goër S., and D. Vaulot, 1999. Bolidomonas: a new genus with two species belonging to a new algal class, the Bolidophyceae class. nov. (Heterokonta). Journal of Phycology, 35, 368-381.
Guillou, L., Moon-Van der Staay, S. Y, Claustre, H., Partensky, F. and D. Vaulot, 1999. Diversity and abundance of Bolidophyceae (Heterokonta) in oceanic waters. Applied and Environmental Microbiology, 65, 4528-4536.
Hess W.R., Steglich C., Lichtlé C. and F. Partensky, 1999. The phycoerythrins of Prochlorococcus marinus are associated to the thylakoid membranes and are encoded by a single large gene cluster. Plant Molecular Biology, 40, 507-521
Moon-van der Staay S.Y., van der Staay G.W.M, Guillou L, Claustre H, and D. Vaulot, 2000. Abundance and diversity of Prymnesiophyceae in picoplankton communities from the equatorial Pacific Ocean inferred from 18S rDNA sequences. Limnology and Oceanography, 45, 98-109.
Van der Staay G.W.M., and F. Partensky, 1999. The 21 kDa protein associated with Photosystem I in Prochlorococcus marinus is the PsaF protein (AJ131438). Plant Physiology 120, 339. (Plant Gene Register # PGR99-067).