Increased water temperature and ocean acidification, due to climate change, is predicted to impact aquatic species’ growth, physiology and calcification rates. The present study investigated how a high-emissions scenario of future water temperature and ocean acidification could influence somatic and otolithic growth, and oxygen isotope fractionation in accreted otolith material, of an important fisheries species, sand whiting (Sillago ciliata) (family Sillaginidae), using an outdoor mesocosm system. The experiment included four treatments with an orthogonal combination of current [∼22 °C], and future [∼25.0 °C] predictions of water temperature and current [∼8.13] and future [∼7.83] pH. Fish somatic and otolithic growth demonstrated a positive response to warmer water temperatures, but were not significantly influenced by increased ocean acidification. Stable oxygen isotopes within otolith material (δ18Ootolith) deposited during the 3-month experimental period, micro-milled from thin-sections and analysed via Isotope Ratio Mass Spectrometry, displayed a negative relationship with water temperature and also varied between acidification treatments. Although acidification increased the intercept of the linear relationship between temperature and oxygen isotope values, the effect was not significant, and the pooled relationship was determined to be δ18Ootolith – δ18Owater = – 0.22*T + 34.34 (R2 = 0.522, p < 0.001). This model demonstrated a similar slope to that for inorganic aragonite and other fish species, but a noticeably higher intercept. This species-specific relationship has fundamental applications for determining water temperature estimates using δ18Ootolith values from wild-caught whiting which may elucidate dispersal and movement patterns, thus offering essential information for informed decision-making amidst a changing climate.

中文翻译：

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气候变化对沙鳕 （Sillago ciliata） 生长和耳石测温的影响


由于气候变化，水温升高和海洋酸化预计将影响水生物种的生长、生理和钙化速度。本研究调查了未来水温和海洋酸化的高排放情景如何影响重要渔业物种沙鳕 （Sillago ciliata） （Sillaginidae） 的体细胞和耳石生长，以及吸积耳石材料中的氧同位素分馏，使用室外中宇宙系统。该实验包括四种处理，对当前 [∼22 °C] 和未来 [∼25.0 °C] 水温以及当前 [∼8.13] 和未来 [∼7.83] pH 值进行正交组合。鱼类体细胞和耳石生长表现出对水温升高的积极反应，但不受海洋酸化增加的显着影响。在为期 3 个月的实验期间沉积的耳石材料 （δ18Ootolith） 中的稳定氧同位素，从薄片微铣削并通过同位素比质谱法分析，与水温呈负相关，并且在酸化处理之间也有所不同。尽管酸化增加了温度和氧同位素值之间线性关系的截距，但效果并不显着，并且合并关系被确定为 δ18Ootolith – δ18Owater = – 0.22*T + 34.34 （R2 = 0.522，p < 0.001）。该模型显示出与无机文石和其他鱼类物种相似的坡度，但截距明显更高。 这种物种特异性关系对于使用野生捕获的鳕鱼的 δ18Ootolith 值确定水温估计具有基本应用，这可能阐明扩散和移动模式，从而为在不断变化的气候中做出明智的决策提供重要信息。