In marine systems, heatwaves cause damages in coastal systems, including extensive coral bleaching and mortality (very high confidence) (Section 3.4.2.1), mass mortality of invertebrate species (low to high confidence, depending on system) (Sections 3.4.2.2, Section 3.4.2.5, Section 3.4.4.1), and abrupt mortality of kelp-forest (high confidence) (Section 3.4.2.3) and seagrass-meadow habitat