A multi-proxy (δ44/40Ca, Sr/Ca, and Δ47) study of fish otoliths for determination of seawater temperature

Mondal, S and Chakrabarti, R and Ghosh, P (2022) A multi-proxy (δ44/40Ca, Sr/Ca, and Δ47) study of fish otoliths for determination of seawater temperature. In: Chemical Geology, 605 .

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Abstract

Fish otoliths are valuable archives for paleotemperature studies. In this study, we have measured δ44/40Ca, Sr/Ca, Mg/Ca, and Ba/Ca ratios in six fish otolith samples of four different species from water with different annual average temperatures ranging from 2 °C to 25 °C. We demonstrate that the δ44/40Ca values of fish otoliths can be used as a temperature proxy. The temperature sensitivity of δ44/40Ca in fish otoliths is 0.036‰/°C which suggests that with the current analytical uncertainty of ±0.08‰ for δ44/40Ca measurements, we can resolve temperature changes of ±2 °C. The Sr/Ca ratio of fish otoliths also shows a negative correlation with water temperature. In addition, both δ44/40Ca values and Sr/Ca of fish otoliths display linear correlations with published δ18O and Δ47 measured in the same otolith powder samples. This study further demonstrates that simultaneous measurements of δ44/40Ca, Sr/Ca, and Δ47 in fish otoliths can be used for robust paleotemperature reconstruction. Using a multi-regression approach, a multi proxy calibration equation is proposed (T (K) = 5.43 × Sr/Ca – 16.8 × δ44/40Ca – 484.6 × Δ47 + 580.9) by combining the δ44/40Ca, Sr/Ca, and Δ47 values in the fish otolith samples, which results in a low uncertainty of temperature estimation of ±0.9 °C. However, the temperature sensitivity of Mg/Ca and Ba/Ca ratios in fish otoliths is not statistically significant and hence, not a reliable proxy for paleotemperature reconstruction.

Item Type:	Journal Article
Publication:	Chemical Geology
Publisher:	Elsevier B.V.
Additional Information:	The copyright for this article belongs to the Elsevier B.V.
Keywords:	Ca stable isotopes; Fish otolith; Multi-proxy measurements; Sea surface temperature reconstruction
Department/Centre:	Division of Mechanical Sciences > Centre for Earth Sciences Division of Mechanical Sciences > Divecha Centre for Climate Change Division of Interdisciplinary Sciences > Interdisciplinary Centre for Water Research
Date Deposited:	05 Jul 2022 11:03
Last Modified:	05 Jul 2022 11:03
URI:	https://eprints.iisc.ac.in/id/eprint/74115

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