Emerging skeletal growth responses of Siderastrea siderea corals to multidecadal anthropogenic impacts in Martinique, Caribbean Sea

Anthropogenic stressors on Caribbean reefs have shifted coral dominance toward stress-tolerant species such as Siderastrea siderea, increasing their importance for reef construction. However, the sublethal responses of these corals to past stressors remain understudied, limiting our understanding of their long-term acclimatization capacity. Here, we reconstructed the annual skeletal growth rates (1912-2020) of twelve S. siderea coral colonies from Martinique (Caribbean Sea) and examined their relationships with changes in human population, sea surface temperature (SST), precipitation, river discharge, and agricultural indicators between 1950 and 2020. Long-term growth rate declines observed since the 1950s were initially associated with human population, a proxy for local stress. Warming SST enhanced coral skeletal growth between 1950 and 1985, suggesting optimal temperatures for calcification during this interval. However, skeletal density exhibited a multidecadal (1950-2020) parabolic response, indicating a surpassing of this thermal optimum in recent decades. This parabolic response included persistent skeletal density declines from 2010 to 2020, possibly related to cumulative thermal stress or the interaction with ocean acidification effects. Our findings suggest a limited acclimatization capacity of long-lived S. siderea corals to cumulative pressures in Martinique and highlight their vulnerability to the compounding effects of local stressors and climate change.