“Temporal and spatial dynamics of the nutricline along a repeated transect in the Western Mediterranean Sea”

Abstract

The temporal and spatial dynamics of the nutriclines (nitracline and phosphacline) depth obtained from in situ measurement of dissolved inorganic nutrients (NO3 and PO4), collected in the Algero Provençal Basin (in a transect between Minorca and Sardinia) from 2005 to 2015, have been analyzed with respect to the Deep Chlorophyll Maximum (DCM) and the Mixed Layer Depth (MLD) dynamics variations. During the research period, the transect region of analysis showed DCM and MLD seasonal variability, with shallower DCM and deeper MLD in summer, were the nutrient limiting factor is highest but the MLD depth exhibit a key role on the nutrient supply to the DCM, contrastingly in winter is observed the deepest DCM and shallowest MLD, were the sunlight is the limiting factor. Results show the key importance of the MLD effect over the DCM nutrient availability, as well as important effects on the nutricline depth related with cyclonic (anticyclonic) shoaling (sinking) eddies, affecting the ND spatial and temporal dynamics. This research reaffirms that the distance between the DCM and the nutriclines affect the nutrient supply to the photic zone, hence the phytoplankton activity. The outcome of these research provides a deeper understanding of the Minorca-Sardinian transect and its ND temporal and spatial dynamics. Keywords: Western Mediterranean Sea, Nutricline depth, Algero Provençal Basin, Deep Chlorophyll Maximum, Mixed Layer Depth.