Testing active fluorometry for studying primary production at high spatial resolution across cyclonic and anticyclonic eddies

Abstract

The study of primary production (PP) in the ocean has traditionally relied on time-consuming techniques, that require incubations, such as 14C-uptake or O2-production measurements, which limit the spatial-temporal resolution that can be achieved. Consequently, the study of the impact of meso- and submesoscale processes on PP at short temporal scales has been constrained to theoretical and indirect measures. Since its development in the 90’s, Active Fluorometry has been proposed as a potential tool to overcome the resolution limits associated with classic methodologies. However, it is the recent generation of active fluorometers that potentially enables the assessment of PP with high spatial resolution and acceptable measurement errors. Here we evaluate PP rates and photophysiology parameters obtained using a Single Turnover Active Fluorometer (LabSTAF) during two cruises across the “Canary Eddy Corridor”, crossing cyclonic and anticyclonic eddies at different life-stages. To assess the equivalence of these measurements, 14C Production-Irradiance (P-I) curves were compared to the Fluorescence Light Curves (FLCs) generated by the LabSTAF. Alongside the P-I curves, 14C uptake was measured after 24-hour incubations under in situ light and temperature conditions and compared with oxygen production rates attained with the LabSTAF.