Antifouling capacity of substrate materials and their effects on settlement and post‐settlement survival of Acropora palmata and Orbicella faveolata

Introduction In coral reef restoration, sexual reproduction is a key methodology to enhance coral population recovery. However, post‐settlement survival remains a major bottleneck, as spat are particularly vulnerable to competition with fouling organisms. The use of substrates with antifouling properties has been proposed as a strategy to reduce fouling pressure and improve early survival. Although multiple substrate materials have been explored globally, the performance of locally sourced alternatives remains poorly evaluated in the Mexican Caribbean. Objectives This study aimed to evaluate the effect of different substrate materials on coral larval settlement, post‐settlement survival, and fouling colonization. Methods Through three experiments, we assessed larval settlement and post‐settlement survival of Acropora palmata and Orbicella faveolata , alongside colonization of substrates by fouling organisms. All assessments were conducted using locally available substrate materials: polymer, carbonate apatite, cement‐based, and Chukum. Results Larval settlement on cement‐based and Chukum substrates was similar to the positive control, while other materials showed no positive effect. No substrate improved post‐settlement survival in ex situ conditions compared to the control. After 2 months in the field, only the carbonate apatite substrate showed reduced fouling colonization compared to the control; other materials performed similarly to it. Conclusions Substrate selection is a critical, goal‐dependent decision in coral reef restoration. While none of the evaluated materials enhanced early post‐settlement survival ex situ, carbonate apatite substrate reduced fouling colonization in the field, and the settlement on cement‐based and Chukum materials was equivalent to the control. These findings highlight the need to align substrate choice with specific restoration objectives.