Estuaries and coastal bays are particularly vulnerable and highly productive areas from an ecological and socioeconomic point of view. These environments are increasingly threatened by anthropogenic pressures. Harmful algal blooms, anoxia-hypoxia events, and high-water temperatures are common threats that can negatively impact the ecosystem and its sustainable use. In this regard, episodes of water quality degradation have recently been reported in bays and coastal areas of the Mediterranean subject to freshwater fluxes, as is the case of Fangar Bay (Ebro Delta). This bay is characterized by a frequent vertical stratification due to freshwater inputs and low renewal rates. To address bay sustainability this paper analyses the temporal evolution of dispersion patterns, using field data from controlled releases of an innocuous tracer (Rhodamine). Results show that water dye dispersion is correlated with the gravitational (estuarine) circulation with seaward flows on the surface layer. The analysis is complemented with data from Lagrangian buoys, local currents from acoustic Doppler velocimeters, unmanned aerial vehicles (UAVs) images, meterological data and CTD surveys.Keywords: estuary; Ebro delta; dye release, diffusivity; rhodamine; Acknowledgements: This work has been funded by the project ECO-BAYS (PID2020-115924RB-I00)

Primary Presenter: Raquel Peñas-Torramilans, Universitat Politècnica de Catalunya (UPC) (raquel.penas@upc.edu)

Authors:

Raquel Peñas-Torramilans, Universitat Politècnica de Catalunya  (raquel.penas@upc.edu)

Manel Grifoll, Universitat Politècnica de Catalunya  (manel.grifoll@upc.edu)

Manuel Espino, Universitat Politècnica de Catalunya  (manuel.espino@upc.edu)

Margarita Fernández, Institute of Agriculture and Food Research and Technology   (margarita.fernandez@irta.cat)

Marta Balsells F-Pedrera, Universitat Politècnica de Catalunya  (marta.balsells@upc.edu)

Yang Chen, Universitat Politènica de Catalunya  (yang.chen1@upc.edu)

Joaquim Sospedra, Universitat Politècnica de Catalunya  (joaquim.sospedra@upc.edu)

Agustín Sánchez-Arcilla, Universitat Politècnica de Catalunya  (agustin.arcilla@upc.edu)