Dynamics of algal overgrowth and predation related tissue loss in corals from the Southern Gulf of California, México (2019–2025)

Introduction: Coral reef ecosystems are undergoing increasing degradation associated with oceanographic changes, higher predation, bioerosion, and anthropogenic pressures, all of which affect their structural complexity, resilience, and functioning. Visible lesions, such as algal overgrowth and tissue loss, serve as practical indicators of colony health. Objective: To characterize the spatial and temporal dynamics of the prevalence of algal overgrowth and predation–related tissue loss lesions, and their relationship with live coral cover, in coral communities of Parque Nacional Zona Marina del Archipiélago de Espíritu Santo (PNZMAES), Gulf of California, between 2019 and 2025. Methods: Annual surveys were conducted by SCUBA diving. At each site, 20 m belt transects were used to quantify benthic composition and record visible lesions on scleractinian coral colonies, classified as algal overgrowth or predation–related tissue loss. Lesion prevalence was calculated at the transect level. Spatial and temporal differences in benthic cover and lesion prevalence were evaluated using PERMANOVA, generalized linear models with quasibinomial distributions, and linear mixed-effects models. Results: Mean benthic composition across all sites was dominated by coral cover (41.7 ± 29.1 %), followed by algal turf (21.2 ± 20.4 %). Coral cover varied significantly among sites, years, and their interaction (p < 0.001). Algal overgrowth was the dominant lesion type, affecting 24.8 % of all colonies, and increased markedly after 2023. Predation-related tissue loss affected 10.3 % of colonies and showed strong spatial heterogeneity. Lesion prevalence differed significantly among coral species (p < 0.001), indicating species-specific susceptibility. Coral cover showed contrasting relationships with lesion types, being negatively associated with predation-related tissue loss and positively associated with algal overgrowth. Conclusions: The marked spatial and temporal heterogeneity in the prevalence of algal overgrowth and predation lesions indicate that coral colonies within the PNZMAES experience contrasting local biotic conditions (e.g., fish communities and coral cover). The increase in algal overgrowth after 2023 suggests ongoing benthic reorganization, while localized predation patterns highlight the importance of site-specific ecological interactions. This study provides a functional baseline for long-term monitoring and demonstrates the utility of lesion prevalence as an indicator of coral reef condition in marginal reef systems of the Eastern Tropical Pacific.