High-resolution marine data are critical to evaluating anthropogenic impacts on our environment. Considering the spatial and temporal limitations of direct instrumental measurements, proxy data extracted from marine environmental archives are necessary to separate anthropogenic changes from those that would occur naturally. The majority of late-Holocene, high resolution environmental reconstructions are derived from marine carbonates including tropical scleractinian corals, bivalves, crustose coralline algae, and sclerosponges. However, these archives are restricted to the top hundreds of meters of the water column, and only preserve environmental variability that is captured by calcium carbonate skeletons. At a very few select locations, marine sediments archive annual environmental variability in organic and inorganic materials. Recently, additional types of corals are proving to yield information complimentary to these traditional marine archives, including cold water scleractinian corals and proteinaceous corals. A taxonomically-diverse group, the proteinaceous corals are broadly defined as those having a branching gross-morphology with skeleton comprised at least partly of protein-rich organic material. They encode characteristics of their food and ambient environment into the chemical and physical composition of their skeleton. This environmental-encoding combined with their banded skeleton and significant longevity means that proteinaceous corals hold information in their skeleton that helps fill the spatial and temporal gaps in our knowledge of past and present ocean conditions.Here I review the environmental reconstructions derived from geochemical measurements of the proteinaceous coral skeletons. This information is grouped into the mesopelagic environmental variability captured in the skeleton of bamboo corals, surface processes captured in the organic skeletons of corals across all ocean depths, and environmental variability documented by skeletal radiometric isotopes. We include animals from two separate subclasses within the class Anthozoa, including the parasitic Zoanthids that secrete a sclero-proteic skeleton. Since the proteinaceous corals are taxonomically diverse, we consider the unique features that define this group of corals including their distribution, morphology, nutrition, and longevity. We find that uncertainty surrounding biological parameters limits the precision of reconstructions derived from the calcitic skeleton; in contrast, analytical effort and cost constrain the number of reconstructions from the organic skeleton. Through this discussion, we provide insights into the uses, challenges, and directions for future research for this important environmental archive. |
