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Factors controlling coral P/Ca nutrient proxy: Insights from Porites culture experiments and synchrotron-based X-ray spectroscopy.
- Source :
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Palaeogeography, Palaeoclimatology, Palaeoecology . Apr2023, Vol. 615, pN.PAG-N.PAG. 1p. - Publication Year :
- 2023
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Abstract
- Coral skeletal P/Ca ratio has been developed as an indicator of temporal seawater dissolved inorganic phosphorus (DIP). The use of coral P/Ca proxy helps to assess oceanographic and climatic impacts such as upwelling, circulation, and continent runoffs on marine biogeochemical cycles. However, factors controlling skeletal P incorporation and elemental partitioning between seawater and coral skeletons remain elusive. We conducted temperature-controlled (∼21 to 29 °C) aquaria culture experiments using two colonies of Porites australiensis corals (here refer to B and C) with the only difference in zooxanthellae density (B > C). The coral growth rate ranges from 9.4 to 19.4 mg/day (B) and 0.7 to 14.1 mg/day (C). Only the growth rate of colony C significantly correlates to temperature, potentially reflecting physiological controls on the two colonies given the difference in the zooxanthellae density. We measured coral P/Ca ratios by Inductively coupled plasma mass spectrometry and determined skeletal P speciation through a synchrotron-based spectroscopic approach. Coral P/Ca ratio ranges from 6.5 to 18.6 μmol/mol (B) and 7.2 to 19.8 μmol/mol (C). The dominance of organic-P is confirmed, and the presence of inorganic-P cannot be excluded. Only colony C has a strong P/Ca dependence on temperature and both colonies show strong correlations between P/Ca and growth rate. Although growth rate and temperature are intercorrelated, the growth rate is more likely the direct controlling factor on coral P/Ca in our experiments. Combined laboratory data with field observations, we suggest that the validity of the Porites P/Ca proxy may be influenced by seawater DIP, coral species, and growth rate. • Cultured coral P/Ca ratio can be variable with relatively constant seawater chemistry. • Organic phosphorus is widely present in coral skeletons despite oxidative cleaning. • The validity of the P/Ca proxy could be influenced by seawater DIP, coral species, and growth rate. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00310182
- Volume :
- 615
- Database :
- Academic Search Index
- Journal :
- Palaeogeography, Palaeoclimatology, Palaeoecology
- Publication Type :
- Academic Journal
- Accession number :
- 162436362
- Full Text :
- https://doi.org/10.1016/j.palaeo.2023.111449