Microbial signatures of protected and impacted Northern Caribbean reefs: changes from Cuba to the Florida Keys.

© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Weber, L., González-Díaz, P., Armenteros, M., Ferrer, V. M., Bretos, F., Bartels, E., Santoro, A. E., & Apprill, A. Microbial signatures of protected and impacted Northern Caribbean reefs: changes from Cuba to the Florida Keys. Environmental Microbiology, 22(1), (2019): 499-519, doi: 10.1111/1462-2920.14870.There are a few baseline reef‐systems available for understanding the microbiology of healthy coral reefs and their surrounding seawater. Here, we examined the seawater microbial ecology of 25 Northern Caribbean reefs varying in human impact and protection in Cuba and the Florida Keys, USA, by measuring nutrient concentrations, microbial abundances, and respiration rates as well as sequencing bacterial and archaeal amplicons and community functional genes. Overall, seawater microbial composition and biogeochemistry were influenced by reef location and hydrogeography. Seawater from the highly protected ‘crown jewel’ offshore reefs in Jardines de la Reina, Cuba had low concentrations of nutrients and organic carbon, abundant Prochlorococcus, and high microbial community alpha diversity. Seawater from the less protected system of Los Canarreos, Cuba had elevated microbial community beta‐diversity whereas waters from the most impacted nearshore reefs in the Florida Keys contained high organic carbon and nitrogen concentrations and potential microbial functions characteristic of microbialized reefs. Each reef system had distinct microbial signatures and within this context, we propose that the protection and offshore nature of Jardines de la Reina may preserve the oligotrophic paradigm and the metabolic dependence of the community on primary production by picocyanobacteria.We thank Justin Ossolinski, Sean McNally, Tom Lankiewicz, Lázaro García, and the crew from R/V Felipe Poey for assistance with sample collection and processing. We thank Marlin Nauticas and Marinas for the use of their dive facilities. We thank Chris Wright, Mark Band, and staff at the University of Illinois W. M. Keck Center for Comparative and Functional Genomics for sequencing assistance, Karen Selph for training in flow cytometry, Krista Longnecker for TOC and TN analyses, and Joe Jennings for nutrient analyses. Funding was provided to A.A. and A.E.S. by a Dalio Explore award from the Dalio Foundation (now 'OceanX') and analysis time was supported with the NSF Graduate Research Fellowship award to L.W. and NSF award OCE 1736288 to A.A. Research was conducted under the LH112 AN (25) 2015 licence granted by the Cuban Center for Inspection and Environmental Control