Improving growth monitoring of Acropora cervicornis in nurseries and outplants at Tayrona National Natural Park, Colombian Caribbean

• The initial size of the fragments affects growth and productivity. • Photometric TLE provides accurate measurement of A. cervicornis growth in nurseries. • Outplant site and structure drive short-term survival and growth more than size. • Orthomosaics are a practical tool to monitor outplant living tissue. Restoration programs throughout the Caribbean are aiming to recover the ecological structure and complexity of coral reefs. In Colombia, line nurseries for Acropora cervicornis were established in the Tayrona National Natural Park and over 11 months, survival, productivity, and growth of 189 fragments were quantified using three variables: maximum linear extension (MLE), total linear extension (TLE), and ecological volume (E), and the growth was compared using manual and photometric methodologies with the aim to suggest guidelines to facilitate monitoring. Subsequently, 66 colonies were outplanted, sorted in two size classes (larger than 100 cm and between 30–100 cm of TLE), attached onto metallic structures, and survival and changes in living tissue were estimated using the structure from motion (SfM) method for one year. The survival of the fragments was higher (70 %) in the nurseries established on mixed coral bottom, and the growth rate was 119.11 ± 55.25 cm/year, with a productivity of 27.96 ± 15.61. In this phase TLE measurement using photometric techniques reduces field work and provides precise growth results. Outplant survival was 91 % and the growth rate of living tissue in the plots was similar; and the SfM method facilitated the reconstruction of outplant areas, offering a less labor-intensive alternative for monitoring at the plot scale. Despite the critical status of A. cervicornis , the results obtained in TNNP were positive, so this protected area could be considered as a key natural refuge to expand restoration efforts to increase coral reef structure.