Understanding ecosystem responses to recurrent marine heatwaves

Marine heatwaves (MHWs) have emerged as an increasingly severe disturbance to global marine ecosystems, with documented intensifications in both frequency and magnitude over the past century. Western Australia has experienced some of the most severe MHWs on record, causing widespread ecological impacts, including coral bleaching and mortality, local species extinctions, and socioeconomic impacts such as fishery closures, making the region a critical case study of climate-driven change in the marine domain. Most recently, a severe MHW during summer 2024/2025 has caused widespread disruption to marine life, reinforcing the region's vulnerability to repeated extreme events. While extensive research has documented the impacts of these events, most studies have examined individual heatwaves or specific taxonomic groups in isolation, limiting our understanding of cumulative and cascading effects across the ecosystem. Here, we combine a scoping review of published and emerging evidence with oceanographic analyses to assess the cumulative ecological impacts of MHWs across Western Australia. Using iconic MHWs as case studies, we reveal widespread ecological consequences, spanning habitat degradation, mass invertebrate mortality events, food web disruption, and spatial redistribution of fisheries' indicator species. Accordingly, we propose adaptive management strategies for future MHWs. These strategies include the relocation of vulnerable species, implementation of adaptive fisheries management frameworks, and development of rapid response monitoring programs targeting key benthic indicator groups. We emphasise that the successful implementation of such strategies hinges upon the accurate and timely prediction of future MHW events.