Interannual variability of the Mediterranean trophic regimes from ocean color satellites

D'Ortenzio and Ribera d'Alcalà (2009, DR09 hereafter) divided the Mediterranean Sea into "bioregions" based on the climatological seasonality (phenology) of phytoplankton. Here we investigate the interannual variability of this bioregionalization. Using 16 years of available ocean color observations (i.e. SeaWiFS and MODIS), we analyzed the spatial distribution of the DR09 trophic regimes on an annual basis. Additionally, we identified new trophic regimes, with seasonal cycles of phytoplankton biomass different from the DR09 climatological description and named "Anomalous". Overall, the classification of the Mediterranean phytoplankton phenology proposed by DR09 (i.e. "No Bloom", "Intermittently", "Bloom" and "Coastal"), is confirmed to be representative of most of the Mediterranean phytoplankton phenologies. The mean spatial distribution of these trophic regimes (i.e. bioregions) over the 16 years studied is also similar to the one proposed by DR09. But at regional scale some annual differences, in their spatial distribution and in the emergence of "Anomalous" trophic regimes, were observed compared to the DR09 description. These dissimilarities with the DR09 study were related to interannual variability in the sub-basin forcing: winter deep convection events, frontal instabilities, inflow of Atlantic or Black Sea Waters and river run-off. The large assortment of phytoplankton phenologies identified in the Mediterranean Sea is thus verified at interannual level, confirming the "sentinel" role of this basin to detect the impact of climate changes on the pelagic environment

Development and validation of the new ProvBioII float

In the last ten years, a productive collaboration has grown between the Laboratoire d’Océanographie de Villefranche (LOV), NKE and IFREMER to implement biogeochemical sensors on profiling floats. A first project (2003) was dedicated to the design of the so-called ProvBio floats (models A and B) that consisted of a PROVOR-CTS3 float instrumented with three new optical sensors: a Wetlabs transmissometer (C-Rover), a 3-wavelength Satlantic radiometer (OCR-503) and an “ECO3” Wetlabs sensor, measuring chlorophyll-a fluorescence, colored dissolved organic matter and particle backscattering coefficients (see First Success of ProvBio floats, Coriolis Letter n°5). Then, the integration of biogeochemical sensors continued in the framework of ProNuts project (2009, autonomously profiling the nitrate concentrations in the ocean: the pronuts project, Coriolis Letter n°8), by equipping a PROVOR with a nitrate concentration sensor. In parallel within the framework of the Carbocean EU project, the ProvCarbon and ProvDo floats were developed as in 2006 by fitting on a PROVOR a C-Rover and a 3830 Aanderaa optode, respectively. They were used to investigate new tools to assess marine carbon sources and sinks. These initial developments have led to a first invaluable dataset and to subsequent papers (Xing et al. 2012, Xing et al. 2011) and report (IOCCG 2011). Nevertheless, the above projects have grown partially dissociated, as related to specific and project-related needs, while a more integrated solution may have a lot of advantages. Undoubtedly, the scientific exploitation of data would be strongly improved if a unique multidisciplinary float, able to measure all accessible parameters, was available. Such a multidisciplinary float would also strongly reduce costs, by sharing the float itself, and by reducing deployment, validation and communication costs. The idea to merge all these sensors on the same profiling float was thus at the origin of the ProvBioII float project, which was developed in the framework of the remOcean and NAOS programs

Copernicus Marine Service Ocean State Report, Issue 3 Introduction

International audienc