Testing the effectiveness of natural and artificial substrates for coral reef restoration at Isla Isabel National Park, Mexico

Abstract

Introduction: The branching coral Pocillopora is the main reef-building species in the Eastern Tropical Pacific (ETP) region. However, their populations have been threatened due to the intense effect of thermal-stress events in the last three decades. As a mitigating response, active restoration strategies have been developed. However, it has not been possible to establish specific protocols along the ETP’s reefs. Objective: To evaluate the efficiency of two different substrates (natural vs. artificial), through coral growth comparison (extension rate and tissue area) in three Pocillopora coral morphospecies within a year. Methods: Coral growth was estimated by two techniques: extension rate and tissue area of P. cf. verrucosa, P. cf. capitata, and P. cf. damicornis every three months during a year. Results: The extension rate and superficial area growth vary among the coral morphospecies P. cf. verrucosa (16.33 mm yr-1 and 168.49 mm2 yr-1), P. cf. capitata (16.25 mm yr-1 and 176.83 mm2 yr-1), and P. cf. damicornis (12.38 mm yr-1 and 87.62 mm2 yr-1). The data reveals that substrate type did not affect Pocillopora growth, yet there was an effect caused by seasonal changes. Conclusions: This study demonstrates that coral restoration can be implemented using both natural and artificial substrata, with no differences in coral growth. We recommend the implementation of coral reef restoration programs, highlighting the importance of initiate during the warm season due to optimal growth performance of P. cf. verrucosa and P. cf capitata species, which improves the effectiveness of management actions in Isla Isabel National Park.