Environmental controls on particle fluxes in the Gulf of Valencia, NW Mediterranean.

Abstract Three instrumented lines were installed on the continental slope and the basin of the Gulf of Valencia for thirteen months (May 2010 to June 2011) aiming to study particle fluxes and their relationship with environmental parameters. Total mass flux varied between 52 mg m−2 d−1 in the central part of the basin and 7199 mg m−2 d−1 in the northern slope sector. The main biogenic constituent was calcium carbonate (estimated fraction) representing more than 26% of the total flux, whereas organic matter and biogenic silica add together 400 m−3 s−1 can be detected at least 155 km to the southwest. The temporal variation of satellite-derived chlorophyll-a abundance and organic matter flux indicated that biogenic material collected in the Gulf of Valencia is related to sea surface spring phytoplankton blooms developing in the northwestern Mediterranean. However, the temporal variation of biogenic silica corresponded better with the usual pattern of deep chlorophyll-a maxima reached during the fall season, suggesting that diatoms are a main component in subsurface phytoplankton blooms.