Stable isotopic composition of deep sea gorgonian corals (Primnoa spp.): a new archive of surface processes.

• Main Authors: Sherwood, O. A., Heikoop, J. M., Scott, D. B., Risk, M. J., Guilderson, T. P., McKinney, R. A.
• Other Authors: United States. Department of Energy.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Lawrence Livermore National Laboratory 2005
• Subjects: Surface Waters; Pacific Ocean; Particulates; Skeleton; Productivity; Oxygen; Seas; 58 Geosciences; Preservation; Calcite; Organic Matter; Carbon; Corals; Zooplankton; 45 Military Technology; Weaponry; And National Defense; Bombs; Pacific; Southern Ocean
• Online Access: https://digital.library.unt.edu/ark:/67531/metadc873454/

The deep-sea gorgonian coral Primnoa spp. lives in the Atlantic and Pacific Oceans at depths of 65-3200 m. This coral has an arborescent growth form with a skeletal axis composed of annual rings made from calcite and gorgonin. It has a lifespan of at least several hundred years. It has been suggested that isotopic profiles from the gorgonin fraction of the skeleton could be used to reconstruct long-term, annual-scale variations in surface productivity. We tested assumptions about the trophic level, intra-colony isotopic reproducibility, and preservation of isotopic signatures in a suite of modern and fossil specimens. Measurements of gorgonin {Delta}{sup 14}C and {delta}{sup 15}N indicate that Primnoa spp. feed mainly on zooplankton and/or sinking particulate organic matter (POM{sub SINK}), and not on suspended POM (POM{sub SUSP}) or dissolved organic carbon (DOC). Gorgonin {delta}{sup 13}C and {delta}{sup 15}N in specimens from NE Pacific shelf waters, NW Atlantic slope waters, the Sea of Japan, and a South Pacific (Southern Ocean sector) seamount were strongly correlated with Levitus 1994 surface apparent oxygen utilization (AOU; the best available measure of surface productivity), demonstrating coupling between skeletal isotopic ratios and biophysical processes in surface water. Time-series isotopic profiles from different sections along the same colony were identical for {delta}{sup 13}C, while {delta}{sup 15}N profiles became more dissimilar with increasing separation along the colony axis. Similarity in C:N, {delta}{sup 13}C and {delta}{sup 15}N between modern and fossil specimens suggest that isotopic signatures are preserved over millennial timescales. Finally, the utility of this new archive was demonstrated by reconstruction of 20th century bomb radiocarbon.