Madrepora oculata and Lophelia pertusa mass and 210Pb-226Ra chronology, Røst Reef, Norway, 2011

• Main Authors: Sabatier, Pierre, Reyss, Jean-Louis, Hall-Spencer, Jason M, Colin, Christophe, Frank, Norbert, Tisnérat-Laborde, Nadine, Bordier, Louise, Douville, Eric
• Format: Dataset
• Language: English
• Published: PANGAEA 2011
• Subjects: Age; lower confidence level; upper confidence level; Carbon-14; modern; error; Comment; Coral polyp; Depth; bottom/max; top/min; EPOCA; European Project on Ocean Acidification; Identification; Latitude; northbound; southbound; Lead-210; standard deviation; Lead-210 activity per mass; Longitude; eastbound; westbound; Lophelia pertusa; mass; Madrepora oculata; Potassium-40; Radium-226; Radium-226 activity per mass; Sample ID; see reference(s); Site; Species; Spectrophotometry; Thorium-228; Uranium-238; Uranium-238 activity per mass; Bomb Peak; Norway; Røst; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.778153; https://doi.org/10.1594/PANGAEA.778153

Here we show the use of the 210Pb-226Ra excess method to determine the growth rate of corals from one of the world's largest known cold-water coral reef, the Røst Reef off Norway. Two large branching framework-forming cold-water coral specimens, one Lophelia pertusa and one Madrepora oculata were collected alive at 350 m water depth from the Røst Reef at ~67° N and ~9° E. Pb and Ra isotopes were measured along the major growth axis of both specimens using low level alpha and gamma spectrometry and the corals trace element compositions were studied using ICP-QMS. Due to the different chemical behaviors of Pb and Ra in the marine environment, 210Pb and 226Ra were not incorporated the same way into the aragonite skeleton of those two cold-water corals. Thus to assess of the growth rates of both specimens we have here taken in consideration the exponential decrease of initially incorporated 210Pb as well as the ingrowth of 210Pb from the decay of 226Ra. Moreover a~post-depositional 210Pb incorporation is found in relation to the Mn-Fe coatings that could not be entirely removed from the oldest parts of the skeletons. The 226Ra activities in both corals were fairly constant, then assuming constant uptake of 210Pb through time the 210Pb-226Ra chronology can be applied to calculate linear growth rate. The 45.5 cm long branch of M. oculata reveals an age of 31 yr and a~linear growth rate of 14.4 ± 1.1 mm yr-1, i.e. 2.6 polyps per year. However, a correction regarding a remaining post-depositional Mn-Fe oxide coating is needed for the base of the specimen. The corrected age tend to confirm the radiocarbon derived basal age of 40 yr (using 14C bomb peak) with a mean growth rate of 2 polyps yr-1. This rate is similar to the one obtained in Aquaria experiments under optimal growth conditions. For the 80 cm-long specimen of L. pertusa a remaining contamination of metal-oxides is observed for the middle and basal part of the coral skeleton, inhibiting similar accurate age and growth rate estimates. However, the youngest ...