Active modulation of the calcifying fluid carbonate chemistry (δ11B, B/Ca) and seasonally invariant coral calcification at sub-tropical limits
Abstract Coral calcification is dependent on both the supply of dissolved inorganic carbon (DIC) and the up-regulation of pH in the calcifying fluid (cf). Using geochemical proxies (δ11B, B/Ca, Sr/Ca, Li/Mg), we show seasonal changes in the pHcf and DICcf for Acropora yongei and Pocillopora damicorn...
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| Autores principales: | , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
Nature Portfolio
2017
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/0fac5da6c98b42d087a8246fc0301b55 |
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| Sumario: | Abstract Coral calcification is dependent on both the supply of dissolved inorganic carbon (DIC) and the up-regulation of pH in the calcifying fluid (cf). Using geochemical proxies (δ11B, B/Ca, Sr/Ca, Li/Mg), we show seasonal changes in the pHcf and DICcf for Acropora yongei and Pocillopora damicornis growing in-situ at Rottnest Island (32°S) in Western Australia. Changes in pHcf range from 8.38 in summer to 8.60 in winter, while DICcf is 25 to 30% higher during summer compared to winter (×1.5 to ×2 seawater). Thus, both variables are up-regulated well above seawater values and are seasonally out of phase with one another. The net effect of this counter-cyclical behaviour between DICcf and pHcf is that the aragonite saturation state of the calcifying fluid (Ωcf) is elevated ~4 times above seawater values and is ~25 to 40% higher during winter compared to summer. Thus, these corals control the chemical composition of the calcifying fluid to help sustain near-constant year-round calcification rates, despite a seasonal seawater temperature range from just ~19° to 24 °C. The ability of corals to up-regulate Ωcf is a key mechanism to optimise biomineralization, and is thus critical for the future of coral calcification under high CO2 conditions. |
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