Impact of skeletal heterogeneity and treatment method on interpretation of environmental variability from the proteinaceous skeletons of deep-sea gorgonian octocorals

Abstract

(2018). Impact of skeletal heterogeneity and treatment method on interpretation of environmental variability from the proteinaceous skeletons of deep-sea gorgonian octocorals. Chemical Geology. In press. doi: 10.1016/j.chemgeo.2017.12 ABSTRACTThe stable isotope geochemistry of gorgonian octocoral skeletons facilitates detailed time series reconstructions of nutrient biogeochemistry. However, comparisons among reconstructions from different locations require realistic estimates of the uncertainty surrounding each measured geochemical value. Here, we determine quantitative uncertainties related to 1) standard skeletal pretreatment in preparation for stable isotopic analysis and 2) biological variability associated with a heterogeneous isotopic composition of the gorgonin skeleton. We found that the 5% HCl pretreatment required for the δ 13 C measurements does not significantly impact the δ 15 N values of the skeleton nor the reproducibility of the δ 15 N measurements. In contrast, while 5% HCl pretreatment significantly altered bulk δ 13 C values via removal of CaCO 3 , it did not change amino acid δ 13 C values in the organic skeleton. We found that the variance of repeat measurements of skeleton samples formed contemporaneously and homogenized skeleton for both δ 13 C and δ 15 N exceeded that of instrumental uncertainty of an acetanilide standard. This indicates that instrumental uncertainty underestimates the true precision of an isotopic measurement of the organic skeleton. Furthermore, measurements of contemporaneous skeleton around the circumference of an octocoral colony yielded variability exceeding that of homogenized skeleton. Based on these results, we find that 1) both δ 13 C and δ 15 N values can be measured simultaneously in pretreated skeleton, 2) growth bands should be homogenized prior to analysis, and 3) reported error should include uncertainty due to biological effects determined from repeat analysis of homogenized skeleton and not just instrument error to reduce false significant differences. Our results present an important protocol for processing proteinaceous octocoral skeletons and propagating uncertainty to more accurately reconstruct nutrient dynamics from proteinaceous deep-sea octocoral skeletons.

Early development and coloniality in Oligophylloides from the Devonian of Morocco—Are Heterocorallia Palaeozoic octocorals?

“…Primnoidae and Isididae, especially Primnoinae and Keratoisidinae, are closely related, as indicated by molecular studies [ 38 , 39 ], and a transverse section of the axis of one appears rather like the negative image of a section of the other, see e.g. Williams et al (2017, Fig 1) [ 35 ] and Noé & Dullo (2006, Fig 5) [ 37 ]. We therefore postulate that the loculi in Oligophylloides may be interpreted as cavities originally filled with an organic phase and that homologies exists between the wall (proheterotheca and heterotheca) of heterocorals and the stem of certain gorgonians.…”

“…These axes can be entirely proteinaceous, mostly proteinaceous with various amounts of calcareous material (magnesium calcite), or mostly calcareous with various amounts of proteinaceous material [ 30 , 33 , 34 ]. In the genus Primnoa Lamouroux, 1812, fibrous calcareous material is interspersed in the gorgonin matrix [ 35 ], while in the so called “bamboo corals” (family Isididae), despite the solid carbonate appearance of the internodes, gorgonin is present as fibres or sheaths interspersed throughout the calcareous matrix and associated with calcite crystal bundles [ 36 , 37 ]. Primnoidae and Isididae, especially Primnoinae and Keratoisidinae, are closely related, as indicated by molecular studies [ 38 , 39 ], and a transverse section of the axis of one appears rather like the negative image of a section of the other, see e.g.…”

The Nexus Between Vegetation, Urban Air Quality, and Public Health: An Empirical Study of Lahore

“…Atmospheric pollution has imposed a significant burden on the terrestrial environment at both regional and global levels. Pollution is a global issue because it does not have political and geographic boundaries ( 12 ). Still, urban areas worldwide are more affected than rural areas by this noxious matter ( 13 ).…”

Record of the Late Paleozoic Ice Age From Tarim, China

“…Variations in the 18 O/ 16 O ratios of marine sediments record changes in seawater 18 O/ 16 O and temperature (Banner & Hanson, 1990; Grossman, 2012). The carbonate δ 13 C trends and excursions mainly result from partitioning of carbon between organic carbon and carbonate carbon reservoirs, and are important clues to the Earth's paleoclimate, evolution of biota, and carbon dioxide levels in the atmosphere (Kump & Arthur, 1999; Saltzman & Thomas, 2012; Williams et al., 2019). Carbon and oxygen isotope excursions in carbonates have been used as powerful tools for chronostratigraphic correlation (Sansjofre et al., 2011).…”