Marine Heatwaves in the Gulf of Hammamet: A Case Study from Summer 2024

This study focuses on a test case during the summer of 2024 to assess the impact of marine heatwaves on the Gulf of Hammamet ecosystem.The Gulf of Hammamet, located along the eastern coast of Tunisia, is a vital ecological and socio-economic region in the Mediterranean basin. Renowned for its rich marine biodiversity, productive fisheries and Mariculture, and thriving tourism industry, the Gulf supports the livelihoods of coastal communities and plays a key role in regional economic stability. However, this ecosystem is increasingly threatened by the intensification of marine heatwaves, a phenomenon driven by climate change.Marine heatwaves, characterized by prolonged periods of abnormally high sea surface temperatures, have become more frequent and severe in recent decades. These events disrupt the delicate balance of marine ecosystems, leading to biodiversity loss, habitat degradation, and altered fisheries productivity. For the Gulf of Hammamet, these impacts are particularly concerning, as they exacerbate existing vulnerabilities and pose significant challenges to sustainable coastal management. Understanding the mechanisms and consequences of marine heatwaves in this region is essential for enhancing coastal resilience. This study aims to bridge critical knowledge gaps by assessing the physical and ecological impacts of heatwaves in the Gulf of Hammamet, providing valuable insights to inform risk mitigation strategies and adaptive management practices.A high-resolution hydrodynamic model is employed, fed at the open boundaries by Mediterranean Sea Physics Reanalysis provided by Copernicus Marine Service, to capture localized physical processes while maintaining consistency with broader-scale ocean dynamics. The model setup incorporates detailed boundary conditions and region-specific parameters to enhance its predictive capabilities. Key variables, such as sea surface temperature, currents, and heat fluxes, are simulated to analyze the onset, intensity, and progression of marine heatwaves during the specified period. Validation of the model is achieved through comparisons with global datasets and climatological records relevant to summer 2024, ensuring reliable insights without relying on in-situ measurements. This approach enables a robust analysis of how heatwaves influence physical conditions and their cascading effects on the Gulf's ecosystem, including shifts in water column stratification and potential impacts on marine biodiversity.However, we acknowledge that in-situ data are indispensable for a more robust and comprehensive validation of the model, and future efforts will aim to incorporate such datasets to improve accuracy and reliability.