Net community production in the northwestern Mediterranean Sea from glider and buoy measurements

Abstract. The Mediterranean Sea comprises just 0.8 % of the global oceanic surface, yet considering its size, it is regarded as a disproportionately large sink for anthropogenic carbon due to physical and biogeochemical characteristics. An underwater glider mission was carried out in March–April 2016 close BOUSSOLE DyFAMed time series moorings northwestern Sea. deployment served test prototype ion-sensitive field-effect transistor pH sensor. Dissolved oxygen (O2) concentrations optical backscatter were also observed by increased between 19 March 1 April, along with pH. These changes indicated start phytoplankton spring bloom, following period intense mixing. Concurrent measurements CO2 fugacity O2 at mooring buoy showed fluctuations, qualitative agreement pattern measurements. Mean net community production rates (N) estimated from dissolved inorganic (DIC) concentrations, based on their mass budgets. Glider DIC derived salinity-based total alkalinity parameterisation, fugacity. spatial coverage data allowed calculation advective fluxes. N estimates euphotic zone 10 3 April (-17±36) O2, (44±94) DIC, (17±37) (49±86) mmolm-2d-1 all indicating metabolic balance over these 25 d. However, d actually split into increase decrease April. latter interpreted onset bloom. regression coefficients DIC-based 0.25 ± 0.08 0.54 0.06 buoy, significantly lower than canonical quotient 1.45±0.15. This study shows added value co-locating profiling moored buoys, but demonstrates difficulty estimating N, limitations achievable precision.