EFFECTS OF GENOTYPE AND ENVIRONMENT ON CULTURED CORALS FOLLOWING RESTORATION

The threatened staghorn coral Acropora cervicornis is widely cultured throughout south Florida and the Caribbean for use in restoration. Despite overall success in rearing this species using in situ nurseries, outcomes following restoration to natural reefs can be variable, and genotype- and site-specific differences in survival and growth have been reported. Recent work has demonstrated significant phenotypic variability among A. cervicornis reared in a common garden nursery, including differences in the rate of extension, branch formation, and calcification, as well as variability in thermotolerance. Selecting a higher proportion of robust genotypes for outplanting could improve overall rates of growth and survival in restoration efforts. However, it remains unclear whether phenotype is conserved following outplanting to natural reefs, particularly across very different reef types.

We conducted a study to determine the effects of both genotype and site on restored A. cervicornis. Six genotypes with previously determined phenotypes related to growth and thermotolerance were individually tagged and planted across four sites (two inshore patch reefs, and two offshore forereefs) using marine epoxy. Total linear extension and colony length, width, and height (to estimate volume) were measured for each colony immediately prior to outplanting. After 51 days, colony mortality, length, width, and height were measured. No significant difference in colony survival was found among sites. Growth differed among genotypes (Fig.1; F=2.278, df=5, p<0.05) and was higher at inshore sites compared to offshore sites, (F=6.469, df=1, p<0.05), but the interaction of genotype and site type was not significant.

These preliminary results suggest differences in growth phenotypes are present following restoration. Additional measurements are required to fully determine whether phenotypes following restoration are consistent with those measured in a common garden nursery setting. Lower growth at offshore sites could suggest higher rates of colony breakage compared to more protected, inshore sites. Monitoring will continue for a period of one year to better understand long-term trends and the role of both genotype and site.