Sclerochronological approaches using fish otoliths provide a powerful and cost-effective means to evaluate fish responses to environmental variations in regions where there is a paucity of long-term data. We hypothesised that the dynamism in the environmental conditions associated with El Niño Southern Oscillation (ENSO) events in the Southern Atlantic Ocean would likely influence growth patterns and chemical records in fish otoliths. Hence, we developed a 46-year otolith increment-based growth chronology, and otolith chemical chronologies of Sr:Ca and Ba:Ca for an iconic top predatory fish, the dusky grouper Epinephelus marginatus collected off the southern coast of Brazil. Using a set of increasingly complex mixed-effects linear models, our biochronological approach revealed the influence of intrinsic and large-scale environmental drivers on growth and otolith chemical composition of dusky grouper. In particular, the intensity of the Multivariate ENSO index (a measure of the status of ENSO and El Niño or La Niña conditions) was negatively associated with growth, with rapid drops in average growth evident in very strong El Niño events (1992–93, 1997–98, or 2015–16). Similar negative relationships between ENSO and Ba:Ca composition reflected variations in environmental histories of dusky groupers, a species that is mostly sedentary in coastal reefs, whilst no environmental effects were detected for Sr:Ca. Overall, identifying the drivers that underlie variations in fish growth is a crucial challenge for any conservation or fisheries interest species as population dynamics, persistence and sustainable harvesting are tightly linked to individual growth. The development of chemical chronologies provided insight towards relating otolith elemental variation to environmental conditions at multidecadal scales, encouraging further evaluations of individual and population-level fluctuations of otolith chemistry and environmental reconstructions.

使用鱼类耳石的年代学方法为评估缺乏长期数据的区域中鱼类对环境变化的反应提供了一种强大且具有成本效益的方法。我们假设，与大西洋南部的厄尔尼诺现象有关的环境条件下的动力学可能会影响鱼类耳石的生长方式和化学记录。因此，我们开发了46年基于耳石增量的生长年表，以及Sr：Ca和Ba：Ca耳石化学年表，用于标志性的顶级掠食性鱼类，黑斑石斑鱼Epinephelus marginatus收集在巴西南部海岸附近。使用一组日益复杂的混合效应线性模型，我们的生物年代学方法揭示了内在和大规模环境驱动因素对暗斑石斑鱼生长和耳石化学成分的影响。特别是，多变量ENSO指数（衡量ENSO和厄尔尼诺或拉尼娜状况的强度）的强度与增长呈负相关，在非常强烈的厄尔尼诺事件（1992-93年， 1997–98或2015–16）。ENSO与Ba：Ca组成之间的相似负相关关系反映了暗礁石斑鱼的环境历史变化，该种石斑鱼在沿海礁石中大多是久坐的，而未发现Sr：Ca的环境影响。总体，由于种群动态，持久性和可持续的捕捞与个人生长紧密相关，因此，确定造成鱼类生长变化的动因是任何保护或渔业利益物种面临的关键挑战。化学年代学的发展提供了将耳石元素变化与环境条件联系起来的见识，涉及数十年尺度，鼓励进一步评估耳石化学和环境重建的个体和群体水平波动。