Samples for dissolved inorganic carbon (TCARBN) and total alkalinity (ALKALI) were collected into acid washed 500 cm 3 borosilicate glass bottles and poisoned with 200 mm 3 of a 36 g.m 3 HgCl 2 , as recommended by Dickson et al. (2007). Samples were stored in the dark at 4 °C for 1–6 months before analysis. Measurements of TCARBN and ALKALI were performed simultaneously by potentiometric acid titration using a closed cell following the methods described by Edmond (1970) and Dickson and Goyet. (1994). Analyses were performed at the National facility for analysis of carbonate system parameters (SNAPO-CO 2 , LOCEAN, Sor­bonne University – CNRS, France). Average accuracy of ALKALI and TCARBN analysis was 2.3 and 2.6 μmol.kg 1 , respectively, validated using Certified Reference Material (CRM) provided by A. Dickson’s laboratory (Scripps Institution of Oceanog­raphy, San Diego).
The pH was measured spectrophotometrically at the MIO (Mediter­ranean Institute of Oceanography, Marseille – France). Unpurified m-cresol purple (McP) dye (Sigma®) at standard temperature (25 ° C) was used and results are reported on the total hydrogen ion concentration scale. Measurements were performed following the protocol described by Clayton and Byrne (1993). The parameter PHT25 was calculated following Dickson et al. (2007). The reproducibility of the measurements based on replicates measurements was 0.001.
Unfiltered samples were collected for nutrient analysis in 60 cm3 polyethylene flasks and immediately frozen. Nutrient concentrations were obtained following the protocol of Aminot and Kerouel, 2007. Detection limits for nitrite NITRIT, NITRAT, and SILCAT were of 0.05 μmol.kg -1 and 0.003–0.006 μmol.kg -1 for PHPHAT.

Dissolved oxygen (DOXY) has been measured by winkler titration with potentiometric endpoint detection.