Institute of International Rivers and Eco-Security, Yunnan University, Kunming, China.
Yunnan Key Laboratory of International Rivers and Transboundary Eco-Security, Yunnan University, Kunming, China.
Glob Chang Biol. 2024 Sep;30(9):e17501. doi: 10.1111/gcb.17501.
Otoliths are frequently used as proxies to examine the impacts of climate change on fish growth in marine and freshwater ecosystems worldwide. However, the large sensitivity differences in otolith growth responses to typical changing environmental factors (i.e., temperature and CO concentration), coupled with unclear drivers and potential inconsistencies with fish body growth, fundamentally challenge the reliability of such otolith applications. Here, we performed a global meta-analysis of experiments investigating the direct effects of warming (297 cases) and CO acidification (293 cases) on fish otolith growth and compared them with fish body growth responses. Hierarchical models were used to assess the overall effect and quantify the influence of nine explanatory factors (e.g., fish feeding habit, life history stage, habitat type, and experimental amplitude and duration). The overall effects of warming and acidification on otolith growth were positive and significant, and the effect size of warming (effect size = 0.4003, otolith size of the treatment group increased by 49.23% compared to that of the control group) was larger than that of acidification (0.0724, 7.51%). All factors examined contributed to the heterogeneity of effect sizes, with larger responses commonly observed in carnivorous fish, marine species, and young individuals. Warming amplitudes and durations and acidification amplitudes increased the effect sizes, while acidification durations decreased the effect sizes. Otolith growth responses were consistent with, but greater than, fish body growth responses under warming. In contrast, fish body growth responses were not significant under acidification (effect size = -0.0051, p = .6185) and thus cannot be estimated using otoliths. Therefore, our study highlights that the reliability of applying otoliths to examine climate change impacts is likely varied, as the sensitivity of otolith growth responses and the consistency between the growth responses of otoliths and fish bodies are context-dependent.
耳石经常被用作代理，以研究气候变化对全球海洋和淡水生态系统中鱼类生长的影响。然而，耳石生长对典型环境变化因素（即温度和 CO 浓度）的响应存在较大的敏感性差异，加上不清楚的驱动因素和与鱼类身体生长的潜在不一致性，从根本上挑战了这种耳石应用的可靠性。在这里，我们对研究升温（297 个案例）和 CO 酸化（293 个案例）对鱼类耳石生长直接影响的实验进行了全球荟萃分析，并将其与鱼类身体生长的响应进行了比较。分层模型用于评估总体效应，并量化了九个解释因素（例如，鱼类摄食习性、生活史阶段、栖息地类型以及实验幅度和持续时间）的影响。升温和酸化对耳石生长的总体影响是积极且显著的，升温的效应大小（效应大小=0.4003，处理组的耳石大小比对照组增加了 49.23%）大于酸化的效应大小（0.0724，7.51%）。所有检查的因素都导致了效应大小的异质性，通常在肉食性鱼类、海洋物种和幼鱼中观察到较大的响应。升温幅度和持续时间以及酸化幅度增加了效应大小，而酸化持续时间降低了效应大小。在升温条件下，耳石生长的响应与鱼类身体生长的响应一致，但大于后者。相比之下，鱼类身体生长的响应在酸化条件下并不显著（效应大小=−0.0051，p=0.6185），因此不能使用耳石来估计。因此，我们的研究强调，应用耳石来研究气候变化影响的可靠性可能存在差异，因为耳石生长响应的敏感性以及耳石和鱼类身体生长响应之间的一致性是取决于背景的。
