Abstract Summary
Coral reefs worldwide are threatened due to ocean warming and acidification, and their persistence hinges on corals capacity for adaptation. To maximize adaptive potential, coral genotypes with increased phenotypic resilience to climate change conditions should be selected for restoration. Corals from Kāne’ohe Bay (Oahu, HI) would be excellent candidates for this as they currently experience temperatures and pH levels not expected to occur on most Hawaiian reefs for another 30-50 years, and are likely locally adapted to their environment. We hypothesize that Kāne’ohe Bay corals (a) are phenotypically distinct from conspecific populations on other nearby reefs, and (b) possess certain phenotypic traits that facilitate their resilience. To investigate this, a variety of morphotypes (e.g. branching, mounding, encrusting) of eight species (constituting ~97% of the coral cover across the Hawaiian archipelago) were sampled from six sites around Oahu, which during the summer, span a natural range of temperature and pH profiles representative of today, through those predicted by 2050. Biomass, protein, and chlorophyll a concentration were quantified in each species from each site. Preliminary results suggest that phenotypic diversity is greatest among species and morphotypes, and contrary to hypothesis (a), differences due to environment are less pronounced. This suggests that morphotype variation may be more important than previously thought for yielding greater adaptive potential when selecting corals for restoration. Furthermore, no evidence was found to support hypothesis (b) as all variables influenced phenotypic variation equally. However, further research (including quantification of Symbiodinium density, carbohydrates, total lipids, lipid class analysis, and heterotrophic capacity) is being conducted to further investigate phenotypic resilience traits. Overall, this survey contributes to our understanding of source coral variability that can inform sampling practices for maximizing adaptive potential.
