Near complete local extinction of iconic anemonefish and their anemone hosts following a heat stress event

Near complete local extinction of iconic anemonefish and their anemone hosts following a heat stress event
npj Biodiversity 4:35 (2025) Bennett-Smith et al.

This study documents the catastrophic impact of the 2023 marine heatwave in the central Red Sea, where anemonefish (Amphiprion bicinctus) and their host sea anemones (Radianthus magnifica) suffered near-complete collapse. Across three surveyed reefs, we recorded 100% bleaching of host anemones, 94–100% mortality of anemonefish, and up to 94% mortality of anemones following extreme thermal stress reaching 22 °C-weeks. By comparing these findings to other Indo-Pacific sites where such declines were not observed, the study reveals how mutualistic reef species can face local—or even regional—extinction under intensifying climate stress.

The work was featured by National Geographic in September 2025, accompanied by original photography from the Red Sea, and has since been cited in discussions of reef ecosystem collapse and climate resilience.