Cold-water stony corals are found in both the deep sea and at shallow depths in the temperate ocean. Similar to tropical reef forming corals in many respects, cold-water corals differ in at least two important ways: (1) they generally lack photosymbionts, allowing us to separate the effects of photosynthesis from calcification, and (2) many deep-sea coral inhabit regions of the ocean characterized by low aragonite saturation states. We need to understand if there are specific adaptations that allow some cold-water coral to grow under acidified conditions. Furthermore, as the deep ocean becomes increasingly acidic we need to determine how these coral will react. To answer these questions we are working with a shallow cold-water coral from the Washington coast.
As part of a comprehensive program to understand biomineralization in marine invertebrates, we are developing cultured cold-water corals into a model system for coral calcification. Combining coral culture and skeletal analysis, these experiments will probe the fundamental links between calcification and ocean acidification. Furthermore, our experiments will also be used to predict the impact of acidification on analogous but experimentally inaccessible species of deep-sea coral. Cold water coral culture will be conducted at Friday Harbor Labs in the newly constructed Ocean Acidification Environmental Laboratory, with skeletal analysis occurring at UW.
Biomineralization affects skeletal chemistry through a series of elementary reactions and processes, with each step leaving behind distinct tracers. Working with cultured coral and modern deep-sea coral, specimens grown in a constant and known environment, we can isolate the biologically-induced signals of biomineralization. We then use these compositional signatures to characterize the mechanisms controlling skeletal growth.
Stony corals are only the beginning – our lab is also developing techniques to study skeletal growth in a range of marine organisms with diverse mineralogies, organisms like calcitic coral, tunicates, and sea urchins.