Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 12, 5021-5039, 2015
https://doi.org/10.5194/bg-12-5021-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
26 Aug 2015
On the vertical distribution of the chlorophyll a concentration in the Mediterranean Sea: a basin-scale and seasonal approach
H. Lavigne1, F. D'Ortenzio2,3, M. Ribera D'Alcalà4, H. Claustre2,3, R. Sauzède2,3, and M. Gacic1 1Istituto Nazionale di Oceanografia e di Geofisica Sperimentale – OGS, Dip. di Oceanografia, Borgo Grotta Gigante 42/c, 34010 Sgonico (Trieste), Italy
2CNRS, UMR 7093, Laboratoire d'Océanographie de Villefranche, 06230 Villefranche-sur-Mer, France
3Université Pierre et Marie Curie, Paris 6, UMR7093, Laboratoire d'Océanographie de Villefranche, 06230 Villefranche-sur-Mer, France
4Laboratorio di Oceanografia Biologica, Stazione Zoologica "A. Dohrn", Villa Comunale, Napoli, Italy
Abstract. The distribution of the chlorophyll a concentration ([Chl a]) in the Mediterranean Sea, mainly obtained from satellite surface observations or from scattered in situ experiments, is updated by analyzing a database of fluorescence profiles converted into [Chl a]. The database, which includes 6790 fluorescence profiles from various origins, was processed with a specific quality control procedure. To ensure homogeneity between the different data sources, 65 % of fluorescence profiles have been intercalibrated on the basis of their concomitant satellite [Chl a] estimation. The climatological pattern of [Chl a] vertical profiles in four key sites of the Mediterranean Sea has been analyzed. Climatological results confirm previous findings over the range of existing [Chl a] values and throughout the principal Mediterranean trophic regimes. They also provide new insights into the seasonal variability in the shape of the vertical [Chl a] profile, inaccessible through remote-sensing observations. An analysis based on the recognition of the general shape of the fluorescence profile was also performed. Although the shape of [Chl a] vertical distribution characterized by a deep chlorophyll maximum (DCM) is ubiquitous during summer, different forms are observed during winter, thus suggesting that factors affecting the vertical distribution of the biomass are complex and highly variable. The [Chl a] spatial distribution in the Mediterranean Sea mimics, on smaller scales, what is observed in the global ocean. As already evidenced by analyzing satellite surface observations, midlatitude- and subtropical-like phytoplankton dynamics coexist in the Mediterranean Sea. Moreover, the Mediterranean DCM variability appears to be characterized by patterns already observed on the global scale.

Citation: Lavigne, H., D'Ortenzio, F., Ribera D'Alcalà, M., Claustre, H., Sauzède, R., and Gacic, M.: On the vertical distribution of the chlorophyll a concentration in the Mediterranean Sea: a basin-scale and seasonal approach, Biogeosciences, 12, 5021-5039, https://doi.org/10.5194/bg-12-5021-2015, 2015.
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The spatiotemporal variability in the vertical distribution of the chlorophyll concentration in the Mediterranean Sea is investigated. Results are based on a large database of fluorescence profiles intercalibrated from ocean color satellite data. They indicate that two types of chlorophyll seasonality coexist in the Mediterranean Sea. The shape of the chlorophyll profile is very dynamic during winter, and the deep chlorophyll maximum is a dominant feature of Mediterranean chlorophyll profile.
The spatiotemporal variability in the vertical distribution of the chlorophyll concentration in...
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