Gli effetti della tempesta Hercules sulla comunità di pesci dell'area marina protetta di Avencas, Portogallo

Marine ecosystems are vital for coastal communities, serving ecological and economic functions. However, they are highly susceptible to environmental perturbations, particularly the increasing threats posed by climate change and extreme weather events, and fish populations can act as bioindicators in detecting these changes. This thesis focuses on understanding the short-term ecological consequences of the Hercules storm, an exceptional meteorological event that hit Portugal's northern littoral in 2014, on the Avencas Marine Protected Area (AMPA) fish communities and its change in abundance of different species. Sampling data collected from 2009 to 2016 were analysed, focusing on changes in fish abundance, species composition, and community dynamics. The results revealed a significant decrease in fish abundance immediately following the Hercules storm, particularly affecting species like Diplodus sargus (Average abundance from 23.85 to 4.39) and Atherina presbyter (Average abundance from 11.36 to 5.47), whose are important components of the local fish community. Remarkably, during the storm, Callionymus lyra, or the Common Dragonet, exhibited the most significant increase in abundance, from 1.03 to 1.86. This shift in abundance may be attributed to the storm's impact on submarine habitats, potentially favouring the proliferation of this species. In conclusion, this study highlights the ecological impacts of extreme storm events on fish communities in a changing climate, emphasizing the importance of continuing research in marine ecosystems to ensure their resilience and sustainability.