Marine heatwaves (MHWs) are prolonged periods of unusually high ocean temperatures that are increasing in frequency and intensity due to climate change. These events can disrupt marine ecosystems by altering water column structure, nutrient availability, dissolved oxygen levels, and biological productivity. Phytoplankton, the foundation of marine food webs and a major driver of global carbon cycling, are particularly sensitive to changes in temperature and ocean chemistry. However, the full impacts of MHWs on phytoplankton dynamics and coastal biodiversity remain poorly understood. Using real-time ocean observation, remote sensing, and AI-driven analysis, this project investigates the effects of marine heatwaves on coastal biodiversity, with a particular focus on phytoplankton. By integrating environmental parameters including sea surface temperature, salinity, dissolved oxygen, and CO₂, we explore hidden correlations and early indicators of ecosystem stress and develop and develop an AI-powered predictive model to support biodiversity monitoring, resilient coastal management, and early warning systems for Harmful Algal Blooms (HABs).