Changes in upwelling regimes in a Mediterranean-type lagoon: A model application

San Quintin Bay (SQB) is a coastal lagoon fertilized with cold, nutrient rich, marine water, that sustains the high productivity within the bay, in particular during upwelling events. The variations in the oceanic exchanges -and in particular changes in upwelling intensity and frequency, also related to climate change- are expected to alter the biogeochemical processes in SQB and in the other coastal systems along the California Current domain with possible impacts on the trophic state. The extent of this influence is tested here developing and applying a 3-D coupled physical-ecological model (SHYFEM-SQBFEEM), contrasted with data. Simulations included a reference scenario (REF) of typical upwelling conditions, observed in spring 2004, and two scenarios of low (LOW) and high (HIGH) upwelling conditions, observed, respectively during spring 2016 and 2005. We calculated the N-budget for the three scenarios, highlighting the response of primary and secondary producers, including oyster potential production, to the changes in upwelling intensity. The model shows that upwelling intensity has a large influence on N availability and consumption within the bay, and on the response of primary and secondary producers. Differences of the nitrogen stocks of primary and secondary producers under HIGH and LOW upwelling conditions are of around 25 % for phytoplankton, 20 % for oyster and more than 40 % for zooplankton.