No abstract

Black corals (order Antipatharia) are important long-lived, habitat-forming, sessile, benthic suspension feeders that are found in all oceans and are usually found in water depths greater than 30 m. Deep-water black corals are some of the slowest-growing, longest-lived deep-sea corals known. Previous age dating of a limited number of black coral samples in the Gulf of Mexico focused on extrapolated ages and growth rates based on skeletal 210 Pb dating. Our results greatly expand the age and growth rate data of black corals from the Gulf of Mexico. Radiocarbon analysis of the oldest Leiopathes sp. specimen from the upper De Soto Slope at 300 m water depth indicates that these animals have been growing continuously for at least the last 2 millennia, with growth rates ranging from 8 to 22 µm yr -1 . Visual growth ring counts based on scanning electron microscopy images were in good agreement with the 14 C-derived ages, suggestive of annual ring formation. The presence of bomb-derived 14 C in the outermost samples confirms sinking particulate organic matter as the dominant carbon source and suggests a link between the deep-sea and surface ocean. There was a high degree of reproducibility found between multiple discs cut from the base of each specimen, as well as within duplicate subsamples. Robust 14 C-derived chronologies and known surface ocean 14 C reservoir age constraints in the Gulf of Mexico provided reliable calendar ages with future application to the development of proxy records. KEY WORDS: Black corals · Radiocarbon age · Growth rates · Gulf of Mexico · Oil spill Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 423: [101][102][103][104][105][106][107][108][109][110][111][112][113][114][115] 2011 growing deep-sea corals relative to some other species (Newton & Bak 1979, Oakley 1988 . A combination of factors such as low frequency of recruitment events, delayed first reproduction, limited larval dispersal, and the demonstrated longevity and slow growth rates suggest that it may take centuries for these species to recover from negative impacts. Longevity seems to be the key factor for population maintenance given the limited and complex genetic flow among black coral populations over long distances, as inferred by molecular markers (Miller 1997, 1998, Miller et al. 2010. Consequently, overexploitation of black corals without proper management could easily lead to local population extinction.Previous age dating in the Gulf of Mexico focused on extrapolated ages and growth rates based on skeletal 210 Pb dating from a limited set of samples (Williams et al. 2006). Using both 'bomb-'produced radiocarbon over the last ~60 yr and conventional 14 C ages (based on the known radioactive decay rate) calibrated with reservoir corrections into calendar ages, robust and reliable ages, as well as growth rates, can be calculated (Roark et al. 2005, 2006, Sherwood et al. 2005). Here we performed radiocarbon measurements on samples selected from 2 distinct ...

No abstract

No abstract

No abstract