**5. Conclusions**

This study on Serranilla island, which is part of the Seaflower BR, has demonstrated that the overall reef fish assemblage is spatially variable with habitat structure explaining up to 66% of this variation [53,57]. In addition, focusing on the parrotfish and their sizes has allowed us to compare sizes and biomasses of fish on Serranilla with those on San Andrés. In combination, the results presented here, together with the intense illegal fishing activities observed in the reserve and other drivers not considered in this study, highlight the need to evaluate other factors that may influence reef fish biodiversity beyond structural complexity [26,73]. Meanwhile biological and ecological information about the current status of most of the key groups in the Seaflower BR remains scarce [67]. Maintaining healthy reef ecosystems is becoming critical, especially in areas where human well-being depends on coral reef ecosystem services, such as food production [73], so that the need for effective management and active surveillance at the Serranilla MPA is urgent.

**Supplementary Materials:** The following are available online at https://www.mdpi.com/article/ 10.3390/oceans2030034/s1, Figure S1: Serranilla Island and distances between islands (San Andres 415 km, Providencia 309 km, Jamaica 305 km), Figure S2: Mean observed fish sizes during census at Serranilla Island (SI) compared with the common and maximum (Max) reported in FishBase, Table S1: Site summary of the metrics of fish assemblages in Serranilla Island with average value per metric ± SD, Table S2: Summary of fish assemblage families and species in Serranilla Island. Values of abundance and biomass with the total sum, frequency, and average ± SD, Table S3: Summary of the abundance and biomass of the Scaridae species in Serranilla and San Andrés with the average values ± SD, Table S4: SIMPER analysis summary. Scaridae average contribution and cumulative contribution percentage in biomass and abundance to the dissimilarity between SI and SAI. Registered and common length of those species.

**Author Contributions:** Conceptualization, D.C., D.M.-d.-A., J.P., A.L.C.-M. and A.S.-M.; Data curation, D.C., J.P. and J.P.E.; Formal analysis, D.C., D.M.-d.-A. and J.P.; Funding acquisition, A.S.-M., D.C. and J.P.; Investigation, D.C., D.M.-d.-A., J.P., A.L.C.-M. and A.S.-M.; Methodology, D.C., D.M.-d.-A., J.P., A.L.C.-M., J.P.E. and A.S.-M.; Supervision, A.L.C.-M. and A.S.-M.; Validation, A.L.C.-M. and A.S.-M.; Visualization, D.C., D.M.-d.-A., J.P. and J.P.E.; Writing—original draft, D.C., D.M.-d.-A., J.P. and A.L.C.-M.; Writing—review and editing, D.C., D.M.-d.-A., J.P., A.L.C.-M., J.P.E. and A.S.-M. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was developed thanks to the funding of the Universidad Nacional de Colombia Sede Caribe on the frame of Seaflower Research Expedition 2017, supported by multiple institutions, including essential contributions from Colombia BIO–Colciencias project and Colombian Ocean Commission (CCO), Project management contract No. FP4484-398-2015, Armada Nacional de Colombia, Corporación para el Desarrollo Sostenible del departamento (Coralina), Gobernación de San Andrés, Providencia y Santa Catalina, and Universidad Nacional de Colombia Sede Caribe. The project under which this research was conducted is "Valoración de servicios ecosistémicos de los arrecifes de coral en los alrededores de la Isla Cayo Serranilla, Reserva de Biosfera Seaflower, Caribe Colombiano," developed and supported by Universidad Nacional de Colombia Sede Caribe. Additional funding included Colciencias Ph.D. scholarship (Conv. 757) and CEMarin (Call 14, 2018) that funded the maintenance of the CEMarin young researcher Julián Prato and the project "Relationships between coral reef complexity and ecosystem services at Caribbean oceanic islands, Seaflower Biosphere Reserve, Colombia". Universidad Nacional de Colombia Sede Caribe funded fish census at San Andrés to Diana Castaño MSc. thesis project "Estructura y Función de peces herbívoros en zonas arrecifales de San Andrés una isla oceánica en el Caribe".

**Data Availability Statement:** The datasets generated during the current study are available within the article and its supplementary materials. Additional data are available from the authors on reasonable request.

**Acknowledgments:** We express our special thanks to the Universidad Nacional de Colombia Sede Caribe for supporting our participation in the Seaflower Research Expedition 2017 "Cayos de Serranilla Island." We thank Armada Nacional de Colombia, Corporación para el Desarrollo Sostenible del Archipiélago de San Andrés, Providencia y Santa Catalina (Coralina), Nacor Bolaños, the crew of the ARC 20 de Julio vessel and Captain and fisherman Casimiro Newball for their support during sailing and sampling at the expedition. We also thank personnel from the Colombian Ocean Commission (CCO) specially to VALM Juan Manuel Soltau, CF Hurtado, CN. Guerra and Juliana Sintura for their important work to make the expedition possible. Finally, we thank Venus Avendaño and Alicia del Mar PC for their multiple support and Omar Abril Howard, Brigitte Gavio, and Violeta Posada for contributing to a successful field working team. We also thank two anonymous referees and the Special Issue editor for their great assistance in improving the manuscript.

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
