New insights about Antarctic gorgonians (Octocorallia, Primnoidae) age, growth and their potential as a paleorecords

Abstract

Antarctic benthic communities have long been defined to be formed by slow-growing and extraordinary long-lived organisms. However, little is known about life history traits of gorgonians –key components of the Antarctic benthos. In this study, colonies of Thouarella variabilis (Wright and Studer, 1889), Fannyella abies(Broch, 1965) and Fannyella rossiiGray, 1872 have been used as target species in order to estimate ages, growth rates and identify their skeletal composition. The radioisotopes 14C and 210Pb used for dating have revealed these colonies to be long-lived with ages spanning from 50 to 1100 years. Radial Growth Rates in this study have also showed to be the slowest rate ever reported for gorgonians (about 6,4 μm yr-1) with apparent growth ring deposition every 2 years. Irregularities in the growth rings were observed also observed as fluctuations in skeletal composition, which may be indicative of changes in the environmental conditions