Acropora cervicornis genet performance and symbiont identity throughout the restoration process

Abstract

In the Caribbean, corals are commonly cultured in ocean-based nurseries and outplanted back to reefs for population enhancement. Intraspecific diversity in host and symbiont is an important consideration for nursery and resource managers. We built upon a previous study that quantified Acropora cervicornis growth phenotypes in a nursery by outplanting the same genets across two reef sites and tracking their performance for 1 yr. Further, we identified the Symbiodinium ‘fitti’ strains present in each of the A. cervicornis genets during the restoration process from the initial wild collection as early as 2008 to 24 months post-outplant in 2017. Survival to 1 yr post-outplant was consistent with regional averages and did not differ significantly among A. cervicornis genets or between outplant sites. Outplant site and host genet had significant effects on coral growth. However, genet growth response did not depend on outplant site, providing no evidence for site-genet matching. Conversely, growth rates measured for each genet in the nursery were not predictive of performance following outplanting. Instead, A. cervicornis genets appear to exhibit differences in relative growth through the restoration process. Despite this variability, relative differences in growth among genets were consistent within a given timeframe, even across varying environments. Most colonies sampled were infected by one of five unique strains of S. ‘fitti’. Host-symbiont specificity varied among coral genets, but four out of five genets exhibited spatial and/or temporal differences in symbiont strain composition throughout the restoration process. The ability for A. cervicornis to associate with more than one S. ‘fitti’ strain and the lack of correlation between nursery and outplant growth performance contribute to a growing understanding of the A. cervicornis population enhancement process.