Effect of benthic organisms on Acropora palmata (Lamarck 1816) fragment survival and growth

Interactions between reef organisms such as overgrowth or release of allelopathic substances, constitute key elements to consider when planning and conducting restoration efforts. We investigated the impact of interactions with benthic organisms on the survival and growth of Acropora palmata fragments outplanted in three reef crests in Cuba. We established a field-based experiment with controls and treatments in each crest that consisted of placing a fragment of A. palmata in proximity to: (1) Porites astreoides , (2) Millepora complanata, (3) Cladophora sp., (4) Sargassum polyceratium, (5) Dictyota sp ., (6) Stypopodium zonale, or (7) Palythoa caribaeorum . Survival and growth of A. palmata fragments varied significantly among control and treatments. The fragments in proximity to P. astreoides showed high survival relative to the controls and overgrew the Porites colonies, suggesting asymmetric competition. In contrast, M. complanata overgrew the fragments, resulting in low fragment survival. A significant interaction between the La Puntica crest and fragments paired with P. astreoides and M. complanata suggests the influence of local environmental conditions on survival and growth of the fragments on this crest. Algal interactions did not significantly impair fragment survival or growth indicating that neighboring macroalgae were not major competitors under the experimental conditions. However, the Stypopodium zonale treatment had a significant positive effect on fragment survival. Crest location significantly influenced fragment survival, with the lowest survival observed at Rincón de Guanabo. The live tissue area of A. palmata fragments generally increased over time across all crests although growth responses varied among associated taxa and locations. Fragments paired with M. complanata consistently exhibited reduced live tissue area relative to controls, while reef crest location significantly influenced growth, with lower live tissue area recorded at Rincón de Guanabo and La Puntica compared with Playa Baracoa. These results highlight that A. palmata fragment survival and growth are affected by biotic interactions and site-specific conditions, underscoring the importance of understanding these processes to inform effective restoration strategies.