Relationship between water and aragonite barium concentrations in aquaria reared juvenile corals
Gonneea, Meagan E.
Cohen, Anne L.
DeCarlo, Thomas M.
Charette, Matthew A.
MetadataShow full item record
Coral barium to calcium (Ba/Ca) ratios have been used to reconstruct records of upwelling, river and groundwater discharge, and sediment and dust input to the coastal ocean. However, this proxy has not yet been explicitly tested to determine if Ba inclusion in the coral skeleton is directly proportional to seawater Ba concentration and to further determine how additional factors such as temperature and calcification rate control coral Ba/Ca ratios. We measured the inclusion of Ba within aquaria reared juvenile corals (Favia fragum) at three temperatures (∼27.7, 24.6 and 22.5 °C) and three seawater Ba concentrations (73, 230 and 450 nmol kg−1). Coral polyps were settled on tiles conditioned with encrusting coralline algae, which complicated chemical analysis of the coral skeletal material grown during the aquaria experiments. We utilized Sr/Ca ratios of encrusting coralline algae (as low as 3.4 mmol mol−1) to correct coral Ba/Ca for this contamination, which was determined to be 26 ± 11% using a two end member mixing model. Notably, there was a large range in Ba/Ca across all treatments, however, we found that Ba inclusion was linear across the full concentration range. The temperature sensitivity of the distribution coefficient is within the range of previously reported values. Finally, calcification rate, which displayed large variability, was not correlated to the distribution coefficient. The observed temperature dependence predicts a change in coral Ba/Ca ratios of 1.1 μmol mol−1 from 20 to 28 °C for typical coastal ocean Ba concentrations of 50 nmol kg−1. Given the linear uptake of Ba by corals observed in this study, coral proxy records that demonstrate peaks of 10–25 μmol mol−1 would require coastal seawater Ba of between 60 and 145 nmol kg−1. Further validation of the coral Ba/Ca proxy requires evaluation of changes in seawater chemistry associated with the environmental perturbation recorded by the coral as well as verification of these results for Porites species, which are widely used in paleo reconstructions.
This paper is not subject to U.S. copyright. The definitive version was published in Geochimica et Cosmochimica Acta 209 (2017): 123-134, doi:10.1016/j.gca.2017.04.006.
Suggested CitationGeochimica et Cosmochimica Acta 209 (2017): 123-134
Showing items related by title, author, creator and subject.
Farfan, Gabriela A.; Cordes, Erik E.; Waller, Rhian G.; DeCarlo, Thomas M.; Hansel, Colleen M. (Frontiers Media, 2018-12-10)In an ocean with rapidly changing chemistry, studies have assessed coral skeletal health under projected ocean acidification (OA) scenarios by characterizing morphological distortions in skeletal architecture and measuring ...
The origin and role of organic matrix in coral calcification: insights from comparing coral skeleton and abiogenic aragonite DeCarlo, Thomas M.; Ren, Haojia; Farfan, Gabriela A. (Frontiers Media, 2018-05-15)Understanding the mechanisms of coral calcification is critical for accurately projecting coral reef futures under ocean acidification and warming. Recent suggestions that calcification is primarily controlled by organic ...
Neodymium isotopes and concentrations in aragonitic scleractinian cold-water coral skeletons - modern calibration and evaluation of palaeo-applications Struve, Torben; van de Flierdt, Tina; Burke, Andrea; Robinson, Laura F.; Hammond, Samantha J.; Crocket, Kirsty C.; Bradtmiller, Louisa I.; Auro, Maureen E.; Mohamed, Kais J.; White, Nicholas J. (Elsevier, 2017-01-27)Cold-water corals (CWCs) are unique archives of mid-depth ocean chemistry and have been used successfully to reconstruct the neodymium (Nd) isotopic composition of seawater from a number of species. High and variable Nd ...