Abstract
Ocean acidification and global warming have been shown to significantly affect the physiological performances of marine calcifiers; however, the underlying mechanisms remain poorly understood. In this study, the transcriptome and biomineralization responses of Pinctada fucata to elevated CO2 (pH 7.8 and pH 7.5) and temperature (25 °C and 31 °C) are investigated. Increases in CO2 and temperature induced significant changes in gene expression, alkaline phosphatase activity, net calcification rates and relative calcium content, whereas no changes are observed in the shell ultrastructure. “Ion and acid-base regulation” related genes and “amino acid metabolism” pathway respond to the elevated CO2 (pH 7.8), suggesting that P. fucata implements a compensatory acid-base mechanism to mitigate the effects of low pH. Additionally, “anti-oxidation”-related genes and “Toll-like receptor signaling”, “arachidonic acid metabolism”, “lysosome” and “other glycan degradation” pathways exhibited responses to elevated temperature (25 °C and 31 °C), suggesting that P. fucata utilizes anti-oxidative and lysosome strategies to alleviate the effects of temperature stress. These responses are energy-consuming processes, which can lead to a decrease in biomineralization capacity. This study therefore is important for understanding the mechanisms by which pearl oysters respond to changing environments and predicting the effects of global climate change on pearl aquaculture.
Highlights
(c,d)) of Pinctada fucata under CO2 and temperature stress
Because this study focuses on the responses of P. fucata to changing seawater environments, the imposed stressors mimic the fluctuations of pH and temperature in the South China Sea (SCS), such that the levels are equivalent to the predictions for Ocean acidification (OA) and warming for the years 2100 and 2300
The net calcification rate (NCR) in P78 reduces by 83.12% at 24 h, 95.26% at 48 h and 102.28% at 72 h compared with the control at the corresponding time points
Summary
(c,d)) of Pinctada fucata under CO2 and temperature stress. The ALP and NCR data are presented as the ratios between the treatment group and the control at the corresponding time point. The pearl oyster Pinctada fucata ( named P. martensii), an economically and ecologically important marine calcifier, is one of the best studied species with respect to biomineralization processes during pearl and shell formation[11,12]. The aims of this study were to elucidate the potential molecular/cellular mechanisms underlying the physiological responses of P. fucata to rapid temperature and pH stress and to examine the effects of these stressors on biomineralization. Because this study focuses on the responses of P. fucata to changing seawater environments, the imposed stressors mimic the fluctuations of pH and temperature in the SCS (pH 7.8, pH 7.5, 25 °C and 31 °C), such that the levels are equivalent to the predictions for OA and warming for the years 2100 and 2300
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