Department Seminar: Fayçal Kessouri

Title: Numerical Modeling to Inform Coastal Management– Application on Harmful Algal Blooms

Abstract: Global change is leading to warming, acidification, and oxygen loss in the ocean. In Southern California, an eastern boundary upwelling system, these stressors are exacerbated by the localized discharge of anthropogenically enhanced nutrients from a coastal population of 23 million people. We use simulations with a submesoscale resolving, physical–biogeochemical model to quantify the link between terrestrial nutrients, organic matter, and carbon inputs and biogeochemical change in the coastal waters of the Southern California Bight:

(1)   We found that the input of anthropogenic nutrients promotes an increase in productivity, remineralization, and respiration offshore, with recurrent oxygen loss and pH decline along the shelf as well as recurring in offshore regions.

(2)   Large-scale ocean climate state, seasonal upwelling, high-frequency eddies, and anthropogenic nutrient inputs all contribute to diatom productivity and its subregional variability. We predict annual maximum domoic acid concentrations and related that to marine mammal stranding events.

(3)   We quantified the role of different sources of anthropogenic nutrients in expanding the window of opportunity for HABs.

(4)   This type of knowledge represents a key context for further information on the role of coastal water quality management in conferring resilience to climate change.