Abstract

Coral reefs are undergoing rapid degradation due to global, regional, and local anthropogenic stressors. Mitigating local stressors could help corals withstand global ones. Here, we assess changes over a quarter century period (1997-2023) in coral colony size-structure, abundance, and distribution of a main Caribbean reef builder, Siderastrea siderea, inside the only no-take zone of Barbados (W. I). During June-Aug 2023, we counted and measured S. siderea colonies on 49 100 m2 quadrats systematically deployed across the no-take zone’s southern reef. We then compared these data with similarly collected data in 1997. Although S. siderea’s relatively high colony density and clumped distribution remained stable between periods, the 2023 data revealed a population now virtually depleted of medium-to-large (diameter>50 cm) colonies (4% of population) compared to 1997 (47%). This rapid and dramatic size-structure shift, despite being in a no-take zone, raises concerns about the long-term persistence of this key coral species in Barbados.