Effects of seawater-pH and biomineralization on the boron isotopic composition of deep-sea bamboo corals
The ocean is currently absorbing excess carbon from anthropogenic emissions, leading to reduced seawater-pH (termed ‘ocean acidification’). Instrumental records of ocean acidification are unavailable from well-ventilated areas of the deep ocean, necessitating proxy records to improve spatio-temporal...
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ftcolumbiauniv:oai:academiccommons.columbia.edu:10.7916/D8Z03716 2023-05-15T17:28:35+02:00 Effects of seawater-pH and biomineralization on the boron isotopic composition of deep-sea bamboo corals Farmer, Jesse Robert Hoenisch, Baerbel Robinson, Laura F. Hill, Tessa M. 2015 https://doi.org/10.7916/D8Z03716 English eng https://doi.org/10.7916/D8Z03716 Paleoclimatology Chemical oceanography Articles 2015 ftcolumbiauniv https://doi.org/10.7916/D8Z03716 2019-04-04T08:12:25Z The ocean is currently absorbing excess carbon from anthropogenic emissions, leading to reduced seawater-pH (termed ‘ocean acidification’). Instrumental records of ocean acidification are unavailable from well-ventilated areas of the deep ocean, necessitating proxy records to improve spatio-temporal understanding on the rate and magnitude of deep ocean acidification. Here we investigate boron, carbon, and oxygen isotopes on live-collected deep-sea bamboo corals (genus Keratoisis) from a pHtot range of 7.5–8.1. These analyses are used to explore the potential for using bamboo coral skeletons as archives of past deep-sea pH and to trace anthropogenic acidification in the subsurface North Atlantic Ocean (850–2000 m water depth). Boron isotope ratios of the most recently secreted calcite of bamboo coral skeletons are close to the calculated isotopic composition of borate anion in seawater (δ11Bborate) for North Atlantic corals, and 1–2‰ higher than δ11Bborate for Pacific corals. Within individual coral skeletons, carbon and oxygen isotopes correlate positively and linearly, a feature associated with vital effects during coral calcification. δ11B variability of 0.5–2‰ is observed within single specimens, which exceeds the expected anthropogenic trend in modern North Atlantic corals. δ11B values are generally elevated in Pacific corals relative to δ11Bborate, which may reflect pH-driven physiological processes aiding coral calcification in environments unfavorable for calcite precipitation. Elevated δ11B values are also observed proximal to the central axis in multiple Atlantic and Pacific specimens, relative to δ11Bborate, which might reflect ontogenetic variability in calcification rates. Although the observed boron isotope variability is too large to resolve the present anthropogenic ocean acidification signal at the studied depths in the North Atlantic (∼0.03–0.07 pH units), pH changes ⩾0.1 units might still be reconstructed using δ11B measurements in bamboo corals. Article in Journal/Newspaper North Atlantic Ocean acidification Columbia University: Academic Commons Pacific |
institution |
Open Polar |
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Columbia University: Academic Commons |
op_collection_id |
ftcolumbiauniv |
language |
English |
topic |
Paleoclimatology Chemical oceanography |
spellingShingle |
Paleoclimatology Chemical oceanography Farmer, Jesse Robert Hoenisch, Baerbel Robinson, Laura F. Hill, Tessa M. Effects of seawater-pH and biomineralization on the boron isotopic composition of deep-sea bamboo corals |
topic_facet |
Paleoclimatology Chemical oceanography |
description |
The ocean is currently absorbing excess carbon from anthropogenic emissions, leading to reduced seawater-pH (termed ‘ocean acidification’). Instrumental records of ocean acidification are unavailable from well-ventilated areas of the deep ocean, necessitating proxy records to improve spatio-temporal understanding on the rate and magnitude of deep ocean acidification. Here we investigate boron, carbon, and oxygen isotopes on live-collected deep-sea bamboo corals (genus Keratoisis) from a pHtot range of 7.5–8.1. These analyses are used to explore the potential for using bamboo coral skeletons as archives of past deep-sea pH and to trace anthropogenic acidification in the subsurface North Atlantic Ocean (850–2000 m water depth). Boron isotope ratios of the most recently secreted calcite of bamboo coral skeletons are close to the calculated isotopic composition of borate anion in seawater (δ11Bborate) for North Atlantic corals, and 1–2‰ higher than δ11Bborate for Pacific corals. Within individual coral skeletons, carbon and oxygen isotopes correlate positively and linearly, a feature associated with vital effects during coral calcification. δ11B variability of 0.5–2‰ is observed within single specimens, which exceeds the expected anthropogenic trend in modern North Atlantic corals. δ11B values are generally elevated in Pacific corals relative to δ11Bborate, which may reflect pH-driven physiological processes aiding coral calcification in environments unfavorable for calcite precipitation. Elevated δ11B values are also observed proximal to the central axis in multiple Atlantic and Pacific specimens, relative to δ11Bborate, which might reflect ontogenetic variability in calcification rates. Although the observed boron isotope variability is too large to resolve the present anthropogenic ocean acidification signal at the studied depths in the North Atlantic (∼0.03–0.07 pH units), pH changes ⩾0.1 units might still be reconstructed using δ11B measurements in bamboo corals. |
format |
Article in Journal/Newspaper |
author |
Farmer, Jesse Robert Hoenisch, Baerbel Robinson, Laura F. Hill, Tessa M. |
author_facet |
Farmer, Jesse Robert Hoenisch, Baerbel Robinson, Laura F. Hill, Tessa M. |
author_sort |
Farmer, Jesse Robert |
title |
Effects of seawater-pH and biomineralization on the boron isotopic composition of deep-sea bamboo corals |
title_short |
Effects of seawater-pH and biomineralization on the boron isotopic composition of deep-sea bamboo corals |
title_full |
Effects of seawater-pH and biomineralization on the boron isotopic composition of deep-sea bamboo corals |
title_fullStr |
Effects of seawater-pH and biomineralization on the boron isotopic composition of deep-sea bamboo corals |
title_full_unstemmed |
Effects of seawater-pH and biomineralization on the boron isotopic composition of deep-sea bamboo corals |
title_sort |
effects of seawater-ph and biomineralization on the boron isotopic composition of deep-sea bamboo corals |
publishDate |
2015 |
url |
https://doi.org/10.7916/D8Z03716 |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
North Atlantic Ocean acidification |
genre_facet |
North Atlantic Ocean acidification |
op_relation |
https://doi.org/10.7916/D8Z03716 |
op_doi |
https://doi.org/10.7916/D8Z03716 |
_version_ |
1766121331582042112 |