Study of the effects of water mass variations on aquaculture facilities off the Valencian coast, Spain

In addition to extreme storm surges that can damage aquaculture cages, rapid temperature changes also pose a threat to aquaculture production. In this context, variations in either water mass pathways and/or local water mass properties can lead to sea temperature variations around aquaculture facilities. There are about 15 aquaculture facilities along the Valencian coast in the western Mediterranean, and many more along the rest of the Spanish Mediterranean coast. These facilities typically produce sea bream, croaker, sea bass and eel, among other species of commercial interest.

In this work, we use 35 years of daily averaged horizontal velocities from the Nemo reanalysis, freely accessible in Copernicus and with a horizontal resolution of about 4.2 km, to study variations in water mass properties (potential temperature, salinity) and/or water mass pathways over the Valencian coasts. First, we have performed an analysis of the ocean currents through a real-empirical orthogonal function approach. Next, we performed a Lagrangian analysis. To this end, we have advected horizontally massless particles forward and backward in time for a total of 6 months. The particles are deployed daily from 1988 to 2021 at model grid points off the Valencian coast. Horizontal advections are performed at 10 and 50 m depth, in order to capture any change near the typical depth of aquaculture cages (at about 20 m depth).