IUCN Red List of Ecosystems: Coral Reefs of the Red Sea and Gulf of Aden

Maher A. Amer, Swaleh Aboud, Tamer Attalla, Matthew D. Tietbohl Talas, Ahmad Ghallab, Sheikheldin M. Elamin, Amjed Ginawy, Gaafar Baomer, Mohamed A. Hassan, Saleem Nawaiseh, Mishal Gudka, Franz Smith, Mohamed H. Farah

The Red Sea and Gulf of Aden constitute a complex and globally significant tropical marine ecosystem characterized and long recognized by exceptional biological diversity and a high degree of endemism. Overall, the region contains an estimated 13,118 km² of coral reefs, representing around 7% of the photic coral reef area assessed globally in the Red List of Ecosystems (5.0% of global coral reef extent according to GCRMN 2025). These exceptional coral reefs are facing increasing pressure from marine heatwaves, coastal development, overfishing, pollution, tourism and recreation, and biological disturbances, though their risk status has not previously been evaluated.
Here, we present the first regional IUCN Red List of Ecosystems (RLE) assessment of coral reef collapse risk in this system, integrating biological observations spanning 1969 – 2025 to estimate change in functioning reef distribution (Criterion A) and biotic condition (Criterion D), combined with mapped reef distribution (Criterion B), historical thermal stress (Criterion C1), and future climate projections (Criterion C2). Current ecosystem risk varied spatially, with the Northern Red Sea (NRS) and Gulf of Aden (GoAden) classified as Vulnerable, and the Central Red Sea (CRS) and Southern Red Sea (SRS) as Endangered. In the NRS, risk based on observed change was driven primarily by thermal-related environmental degradation, whereas change in reef distribution and biotic condition remained least concern; this favorable condition is consistent with documented coral thermal resilience. The Endangered status of the CRS reflected greater biotic degradation alongside continued environmental pressure, while the SRS showed greater change in both reef distribution and biotic condition. GoAden’s overall risk was derived from Criteria B and C, with Criteria A and D assessed as Data Deficient; its classification may be revised upward as additional biological data become available. Despite these differences in risk based on observed change, projected increases in extreme thermal stress resulted in all four ecoregions being classified as Critically Endangered under future climate-driven decline. The spatial differences in current ecosystem risk highlight the importance of protecting reefs that remain in comparatively good condition and supporting recovery where ecological change is more evident, while the shared future climate risk emphasizes the need to strengthen climate adaptation, reduce locally manageable pressures, and accelerate global action to limit climate change.