Modeling the impact of tidal flows on the biological productivity of the Alboran Sea

Abstract

The control of phytoplankton production by tidal forcing in the Alboran Sea is investigated with a high-resolution ocean circulation model coupled to an ecosystem model. The aim of the modeling efforts was to elucidate the role of tides in sustaining the high biological productivity of the Alboran Sea, as compared with the rest of the Mediterranean subbasins. It is shown that tidal forcing accounts for an increase of phytoplankton biomass and primary productivity in the basin of about 40% with respect to a nontidal circulation, and about 60% in the western Alboran Sea alone. The tidal dynamics of the Strait of Gibraltar is shown to be the primary factor in determining the enhancement of productivity, pumping nutrients from depth to the photic zone in the Alboran Sea. Model results indicate that the biological implications of the propagating internal tides are small. These results imply that nutrient transports through the Strait of Gibraltar have to be parametrized in ocean models that do not resolve tides in order to properly represent the biochemical budgets of the Alboran Sea.