Does reef crest zone selection influence Acropora palmata (Lamarck, 1816) fragment survival and growth?

In this study, we evaluated the effects of the crest zones on the survival and growth of Acropora palmata fragments in four sites differentially impacted by multiple natural and anthropogenic stressors. The crests are in the northwest (Playa Baracoa and Rincón de Guanabo) and the south-central region (El Peruano and Mariflores in Jardines de la Reina National Park) of Cuba. We established a field-based experiment with 50 fragments placed in each crest, 25 fragments in the back crest zone and 25 in the fore crest zone, parallel to the shoreline. The water flow intensity was estimated in both crest zones, using the dissolution of plaster discs as an indicator. The survival and growth of fragments were significantly influenced by site-specific and microhabitat conditions. The survival of the A. palmata fragments was high (survival probability: >0.6) in all four crests. Fragments placed in the fore crest zone (p = 0.02) exhibited higher survival than those in the back crest zone. The growth rates were slower (-1.5 to 7.3 cm year-1) than those previously recorded for wild A. palmata colonies and were negatively affected (estimate = -6.1; p = 0.004) in the fore crest zone. The dissolution of the plaster discs did not indicate a marked gradient of water flow between the crest zones, during April and June, but it was significantly higher (p = 0.03) in the fore crest zone in December at El Peruano and Mariflores crests, indicating temporal variations during the monitoring periods. The dissolution of plaster discs, as a proxy for water flow, did not have a significant effect on fragment survival between zones. However, when the dissolution was below approximately 68%, growth declined slightly; above this threshold, growth increased, possibly by higher inferred water flow. At higher levels of water flow (dissolution of the plaster discs), the positive effect of temperature on growth was attenuated (p = 0.007), suggesting that under strong water flow heat may be dissipated. These results highlight the importance of conducting small-scale pilot studies to identify the microhabitat conditions and to select effective restoration sites. We recommend that future restoration efforts should integrate local ecological knowledge with in situ environmental measurements to enhance coral fragment survival and growth, and to improve the long-term success of restoration interventions under variable and changing reef conditions.