Towards the Prediction of Favourable Conditions for the Harmful Algal Bloom Onset of Ostreopsis ovata in the Ligurian Sea Based on Satellite and Model Data

In recent years, the occurrence of Ostreopsis ovata (O. ovata) Harmful Algal Blooms (HAB)has increased in the coasts of the Ligurian Sea, causing problems to the marine environment andhuman health. Favourable conditions for O. ovata bloom are triggered by many drivers, many ofwhich are still under investigation, but we hypothesize that this phenomenon can be simulated usinga reduced number of major meteo-marine factors, namely water temperature and remixing. Satelliteand model data obtained and derived from Copernicus service, namely Sea Surface Temperature(SST) and SignificantWave Height (SWH), were therefore investigated as possible proxies of theselocal factors. A simplified conceptual model, built on such proxies, was developed and applied toyield a synthetic indicator informative on O. ovata abundance. The model was tested in two studyareas in the Ligurian Sea, Marina di Pisa and Marina di Massa in Tuscany, Italy. The results obtainedshow that the synthetic indicator is able to account for about 35% of the temporal variability ofO. ovata bloom occurrence in the two study areas.