Environmental and biological controls on Na∕Ca ratios in scleractinian cold-water corals

Abstract

Abstract. Here we present a comprehensive attempt to correlate aragonitic Na∕Ca ratios from Desmophyllum pertusum (formerly known as Lophelia pertusa), Madrepora oculata and a caryophylliid cold-water coral (CWC) species with different seawater parameters such as temperature, salinity and pH. Living CWC specimens were collected from 16 different locations and analyzed for their Na∕Ca ratios using solution-based inductively coupled plasma-optical emission spectrometry (ICP-OES) measurements. The results reveal no apparent correlation with salinity (30.1–40.57 g kg−1) but a significant inverse correlation with temperature (-0.31±0.04 mmolmol-1∘C-1). Other marine aragonitic organisms such as Mytilus edulis (inner aragonitic shell portion) and Porites sp. exhibit similar results highlighting the consistency of the calculated CWC regressions. Corresponding Na∕Mg ratios show a similar temperature sensitivity to Na∕Ca ratios, but the combination of two ratios appears to reduce the impact of vital effects and domain-dependent geochemical variation. The high degree of scatter and elemental heterogeneities between the different skeletal features in both Na∕Ca and Na∕Mg, however, limit the use of these ratios as a proxy and/or make a high number of samples necessary. Additionally, we explore two models to explain the observed temperature sensitivity of Na∕Ca ratios for an open and semi-enclosed calcifying space based on temperature-sensitive Na- and Ca-pumping enzymes and transport proteins that change the composition of the calcifying fluid and consequently the skeletal Na∕Ca ratio.

Host influenced geochemical signature in the parasitic foraminifer Hyrrokkin sarcophaga

“…5). Naturally, the foraminifer would also reflect other characteristics of the host, such as the high Sr/Ca ratio from the aragonite of L. pertusa (Raddatz et al, 2013;Schleinkofer et al, 2019). In agreement with the much lower Sr/Ca ratios in calcite and aragonite in A. excavata (Schleinkofer et al, 2021) compared to the coralline aragonite, we do not observe such high Sr/Ca ratios in HA.…”

Constraining past environmental changes of cold‐water coral mounds with geochemical proxies in corals and foraminifera

“…To date there are only a few studies that systematically evaluate the impact of seawater salinity or temperature on Na incorporation into cold-water Scleractinia. For example, the study by Rollion-Bard and Blamart (2015) suggests that changes in growth rate due to varying seawater temperature might control the incorporation of Na (Li and Mg) and the studies of Rollion-Bard et al (2017) and Schleinkofer et al (2019) imply that a temperature control on Na/Ca ratios might also exist in aragonitic marine species.…”

An Experimental Approach to Assessing the Roles of Magnesium, Calcium, and Carbonate Ratios in Marine Carbonates

“…DIC and T A were calculated for equilibrium carbonate chemistry in NaCl using the dissociation constants of [41]. Although the concentration of calcium in the ECF is known to vary, previous studies have recorded values between 9-15 mM from cold-water corals 9-12.3 mM with a mean of 9.9 mM; [42] and the tropical corals Pocillopora damicornis and Acropora youngei range between ca. 9-15 mM; [43].…”