11/26/2022 0 Comments Benner lab project pisces![]() Radiocarbon measurements were also done on living polyp tissue samples from both specimens. To confirm the trophic-level interpretation and acquire additional growth-rate estimates, we determined the 14C content at 100-μm resolution on the outer few millimeters of a live-collected Gerardia branch from Cross Seamount, and the basal stalk of 1 live-collected Leiopathes from Lanikai, Hawai'i. Assuming classic trophic level enrichments ( 12, 13), these results indicate Gerardia and Leiopathes are low-order consumers, primarily feeding upon freshly exported POM. Typical skeletal δ 15N (+8.7 ± 0.2 ‰) values of one Gerardia specimen are within the error of the tissue measurements, while the skeletal δ 13C (–16.3 ± 0.3 ‰) measurements are ≈3 ‰ more positive because lipids from the tissues are most likely not being incorporated into the skeleton. The slight difference in δ 15N that we observe is not statistically significant because of the small Leiopathes sample size. δ 13C values of live polyp tissues from both Gerardia (10 specimens) and Leiopathes (2 specimens) from 2 different locations are similar. The δ 13C of Hawai'ian particulate carbon at 150 m at Station ALOHA varies from –18 to –22 ‰ (average –21 ± 1 ‰ ) ( 9, 10), while the δ 15N of sinking particulate nitrogen range from +2 to +4 ‰ ( 11). Results Sources of Carbon.Ĭarbon and nitrogen isotopic composition of living polyp tissue taken from specimens collected at the Lanikai DSC bed and Cross Seamount is compared with the isotopic ratios of water particulate organic matter (POM) ( Fig. Resolution of the food (carbon) source and its impact, if any, on radiocarbon age estimates remains a contentious issue. A Hawai'ian Leiopathes specimen from the Makapuu DSC bed had a 14C-estimated life span of 2,320 ± 20 years (radial growth rate ≈5 μm year −1) ( 5). 210Pb measurements on 2 Atlantic Leiopathes specimens suggested life spans of ≈200 to ≈500 years and radial growth rates of ≈15 μm year −1 ( 8). The discrepancies between the radiocarbon, amino acid, and growth-band age estimates were attributed to the incorporation of 14C-free (i.e., old) carbon into the Gerardia skeleton, thereby producing anomalously old 14C ages ( 6, 7). These results contrast with a life span of 250 ± 70 years calculated for the same Atlantic specimen using amino acid racemization ( 6) and a maximum life span of 70 years for Hawai'ian Gerardia specimens, based on counts of what were assumed to be annual growth rings ( 7). Previous radiocarbon studies have shown that individual Gerardia colonies from the Atlantic and Pacific Oceans have life spans of ≈1,800 ± 300 ( 4) and 2,740 ± 15 years ( 5), respectively. In light of their unusual longevity, a better understanding of deep-sea coral ecology and their interrelationships with associated benthic communities is needed to inform coherent international conservation strategies for these important deep-sea habitat-forming species. The management and conservation of deep-sea coral communities is challenged by their commercial harvest for the jewelry trade and damage caused by deep-water fishing practices. specimens were 2,742 years and 4,265 years, respectively. show that radial growth rates are as low as 4 to 35 μm year −1 and that individual colony longevities are on the order of thousands of years. Newly applied radiocarbon age dates from the deep water proteinaceous corals Gerardia sp. Deep-sea coral communities are hotspots of deep ocean biomass and biodiversity, providing critical habitat for fish and invertebrates. Deep-sea corals are found on hard substrates on seamounts and continental margins worldwide at depths of 300 to ≈3,000 m. ![]()
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