Geochemical responses of scleractinian corals to nutrient stress
Geochemical responses of scleractinian corals to nutrient stress
The impact of changing nutrient conditions on scleractinian coral-based geochemical proxies is poorly understood, despite the nutrient balance in many coral reefs being disturbed by anthropogenic activity. Here, the geochemical responses of tropical corals Acropora polystoma and Porites lichen to nutrient enrichment and depletion are examined following growth under cultured conditions, to assess the impact of nutrients on traditional geochemical proxies for both temperature and the coral internal carbonate system. The corals were
exposed to four different nutrient treatments over a period of 140 days: (1) a replete treatment with optimal levels of nitrate (~4.5 μM) and phosphate (~0.6 μM), (2) a nutrient depleted treatment with negligible nitrate and phosphate, (3) a treatment with high nitrate (~73 μM) and negligible phosphate, and (4) a treatment with high phosphate (~5.7 μM) and negligible nitrate. Results suggest nutrients play a hitherto under-appreciated role in coral skeleton elemental (Li/Ca, B/Ca, Mg/Ca, Sr/Ca, Li/Mg) and isotopic (δ11B) composition, with the internal carbonate chemistry also impacted. For example, Mg/Ca and Sr/Ca are lower, and Li/Mg higher, in the nutrient imbalanced and deplete treatments compared to the replete treatment for both species. Disruption to the carbonate system in corals cultured under imbalanced nutrient conditions is best explained by a decrease in dissolved inorganic carbon flux to the extracellular calcifying medium. Variations in nutrient concentration — or nutrient imbalance — can have dramatic consequences on both reconstructed sea surface temperatures and
ocean or calcification pH, with reconstructed temperatures varying from 7◦C to +52 ◦C, and δ11B-derived pH by up to 0.13 pH units. The impact from anthropogenically-induced nutrient disturbances should therefore be considered when generating temporal records of environments using coral skeletal archives.
Boron isotopes, Coral, Element/Ca, Nutrients
108-124
Standish, Christopher
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Chalk, Thomas
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Saeed, Muhammad
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Lei, Fang
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Buckingham, Michael Christopher
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D'Angelo, Cecilia
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Wiedenmann, Joerg
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Foster, Gavin
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15 June 2023
Standish, Christopher
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Chalk, Thomas
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Saeed, Muhammad
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Lei, Fang
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Buckingham, Michael Christopher
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D'Angelo, Cecilia
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Wiedenmann, Joerg
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Foster, Gavin
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Standish, Christopher, Chalk, Thomas, Saeed, Muhammad, Lei, Fang, Buckingham, Michael Christopher, D'Angelo, Cecilia, Wiedenmann, Joerg and Foster, Gavin
(2023)
Geochemical responses of scleractinian corals to nutrient stress.
Geochimica et Cosmochimica Acta, 351, .
(doi:10.1016/j.gca.2023.04.011).
Abstract
The impact of changing nutrient conditions on scleractinian coral-based geochemical proxies is poorly understood, despite the nutrient balance in many coral reefs being disturbed by anthropogenic activity. Here, the geochemical responses of tropical corals Acropora polystoma and Porites lichen to nutrient enrichment and depletion are examined following growth under cultured conditions, to assess the impact of nutrients on traditional geochemical proxies for both temperature and the coral internal carbonate system. The corals were
exposed to four different nutrient treatments over a period of 140 days: (1) a replete treatment with optimal levels of nitrate (~4.5 μM) and phosphate (~0.6 μM), (2) a nutrient depleted treatment with negligible nitrate and phosphate, (3) a treatment with high nitrate (~73 μM) and negligible phosphate, and (4) a treatment with high phosphate (~5.7 μM) and negligible nitrate. Results suggest nutrients play a hitherto under-appreciated role in coral skeleton elemental (Li/Ca, B/Ca, Mg/Ca, Sr/Ca, Li/Mg) and isotopic (δ11B) composition, with the internal carbonate chemistry also impacted. For example, Mg/Ca and Sr/Ca are lower, and Li/Mg higher, in the nutrient imbalanced and deplete treatments compared to the replete treatment for both species. Disruption to the carbonate system in corals cultured under imbalanced nutrient conditions is best explained by a decrease in dissolved inorganic carbon flux to the extracellular calcifying medium. Variations in nutrient concentration — or nutrient imbalance — can have dramatic consequences on both reconstructed sea surface temperatures and
ocean or calcification pH, with reconstructed temperatures varying from 7◦C to +52 ◦C, and δ11B-derived pH by up to 0.13 pH units. The impact from anthropogenically-induced nutrient disturbances should therefore be considered when generating temporal records of environments using coral skeletal archives.
Text
Standish et al 2023 Geochemical responses of scelactinian corals to nutrient stress
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Accepted/In Press date: 19 April 2023
e-pub ahead of print date: 25 April 2023
Published date: 15 June 2023
Additional Information:
Funding Information:
We thank Robbie Robinson and George Clarke for their support in the maintenance of the experimental aquarium systems of the Coral Reef Laboratory, Dan Doran and Matthew Beverley-Smith are gratefully acknowledged for sample preparation, whilst Andy Milton and Mathew Cooper are thanked for their analytical support. This work was funded by the Leverhulme Trust that supported CDS and TBC, and ERC Advanced Grant Micons2Reefs (#884650), both awarded to GLF. We also acknowledge funding from NERC (Defining Nutritional Bottlenecks of Reef Coral Growth and Stress Tolerance—NE/T001364/1) to JW and CDA.
Publisher Copyright:
© 2023 The Author(s)
Keywords:
Boron isotopes, Coral, Element/Ca, Nutrients
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Local EPrints ID: 476887
URI: http://eprints.soton.ac.uk/id/eprint/476887
ISSN: 0016-7037
PURE UUID: 0f707a72-0f7c-4b1b-8497-04e8ad2e8e43
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Date deposited: 18 May 2023 16:58
Last modified: 17 Mar 2024 03:44
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Author:
Muhammad Saeed
Author:
Fang Lei
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