Decadal longevity and slow growth rates in the deep-water sea pen Halipteris finmarchica (Sars, 1851) (Octocorallia: Pennatulacea): implications for vulnerability and recovery from anthropogenic disturbance

摘要

Growth rates and longevity are key factors in assessing the vulnerability of many invertebrates to anthropogenic disturbance. Sea pens are benthic invertebrates frequently entrained as fisheries bycatch, but whose growth (recovery) rates are poorly known. Here, longevity and growth rates were estimated for the deep-water sea pen Halipteris finmarchica from the Northwest Atlantic and compared to those published for Halipteris willemoesi from the Bering Sea. Axes were cross sectioned to visualise growth rings and estimate longevity and growth rates. Chronology of growth rings was examined with trace element microanalysis of Sr/Ca, Mg/Ca, Ba/Ca and Na/Ca in the axis using Secondary Ion Mass Spectrometry. The relationship between growth rates and environmental variables was investigated. The number of rings ranged from 13 to 22 among 26 colonies. Trace element microanalysis yielded a number of elemental ratio peaks comparable to the number of rings visually determined. Diametric growth rates were significantly smaller than those published for H. willemoesi, while linear growth rates (extension in height) were not different. No significant relationships were detected between growth rates and environmental variables for H. finmarchica. Our data suggest that H. finmarchica is a slow-growing, relatively long-lived organism whose recovery from damage can take over 20 years.