We are working to quantify biological characteristics of gorgonian corals in collaboration with Peter Etnoyer with NCCOS, Bob Stone with Auke Bay Laboratories, and the Channel Islands National Marine Sanctuary through funding from NOAA’s Undersea Research Program. This work builds upon the recent US State of Deep-Sea Corals report.
There are two major components to this research.
1) Identify relationships between growth, rates, ages, colony size, and biomass in gorgonian corals. We are comparing two forms of radiometric dating with different band counting techniques to verify how fast these corals grow, how long they can live for, and over what time frame they form their skeletal growth rings.
2) Evaluate sources of nutrients to these corals, methods of incorporation of the nutrients into the coral skeleton, and changes in these nutrients through time. We are collaborating with the Aquarium of the Pacific for feeding experiments to identify the specific food sources to southern California gorognian corals.
In collected specimens, we identified the movement of amino acids between the polyp tissue and gorgonian skeletal tissue using a compound specific amino acid approach (McMahon et al., 2018). We showed that the δ13C values of amino acids and the δ15N values of “source” amino acids preserved in the proteinaceous skeletons largely reflects the values recorded in the metabolically active polyp tissue. However, we found a consistent δ15N offset between “trophic” amino acids in proteinaceous skeleton and metabolically active polyp tissue, which must be accounted for via a correction factor when determined trophic level of the corals.
In progress, we are reconstructing changes in the nutrients to deep-sea gorgonian specimens from the Gulf of Alaska and the Channel Islands.
Branwen Williams 