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Abstract Over recent decades, the Mediterranean zooxanthellate coral Cladocora caespitosa has experienced recurrent mortality events triggered by marine heatwaves. Its generalised decline has led to its classification as endangered on the IUCN Red List, emphasising the urgent need for population characterisation and monitoring to support conservation efforts. We assessed the population traits and health status of two C. caespitosa populations in the NW Mediterranean Sea, using data from 15 years of long-term monitoring of permanent transects. The two study sites, Cap de Creus and Montgrí (Catalonia, Spain), exhibit contrasting environmental conditions, with Montgrí characterised by higher water temperatures and nutrient concentrations. Our results show that warming-related mortality has consistently affected both populations. However, mortality rates were significantly higher in Cap de Creus, despite the lower water temperatures. These differences suggest that environmental nutrient regimes could play a critical role in mediating long-term responses to warming in C. caespitosa . Populations exposed to higher nutrient concentrations, such as those in Montgrí, might better withstand the energy constraints associated with increased water stratification during summer, particularly under conditions of anthropogenic warming. These findings provide crucial insights into assessing the resilience of this endangered coral to anthropogenic climate change.
Quintano et al. (Mon,) studied this question.