Chemical contaminants are one of the causes of the ongoing degradation of coastal and estuarine nurseries, key functional habitats in which the juveniles of many marine species grow. As chemical contaminants can cause a decrease in the energy available and induce defence mechanisms reducing the amount of energy allocated to life history traits, quantifying their effect on the fitness of juvenile fish is key to understand their population-level consequences. However, these effects are primarily estimated experimentally or in the wild but on a limited number of contaminants or congeners that do not reflect the wide variety of chemical contaminants to which juvenile fish are exposed. To address this issue, we measured concentrations of 14 trace metal elements (TMEs) and bioaccumulative organic contaminants (OCs) in European sea bass juveniles (1-year-old) from three major French nurseries (Seine, Loire and Gironde estuaries). We tested the hypotheses that (i) levels and profiles of contaminants differed among studied nurseries, and ii) fish growth and body condition (based on morphometric measurements and muscle C:N ratio) were lower in individuals with higher contaminant concentrations. Multivariate analyses showed that each nursery had distinct contaminant profiles for both TMEs and OCs, confirming the specific contamination of each estuary, and the large array of contaminants accumulated by sea bass juveniles. Increasing concentrations in some TMEs were associated to decreased growth, and TMEs were consistently related to lower fish body condition. The effect of OCs was more difficult to pinpoint possibly due to operational constraints (i.e., analyses on pooled fish) with contrasting results (i.e., higher growth and decreased body condition). Overall, this study shows that chemical contaminants are related to lower fish growth and body condition at an early life stage in the wild, an effect that can have major consequences if sustained in subsequent ages and associated with a decline in survival and/or reproductive success.

化学污染物是导致沿海和河口苗圃持续退化的原因之一，这些苗圃是许多海洋物种幼体生长的关键功能性栖息地。由于化学污染物会导致可用能量减少并诱导防御机制减少分配给生活史特征的能量，因此量化它们对幼鱼健康的影响是了解其种群水平后果的关键。然而，这些影响主要是通过实验或在野外估计的，但对数量有限的污染物或同源物并不反映幼鱼所暴露的各种化学污染物。为了解决这个问题，我们测量了来自法国三个主要苗圃（塞纳河、卢瓦尔河和吉伦特河河口）的欧洲海鲈幼鱼（1 岁）中 14 种微量金属元素 (TME) 和生物累积性有机污染物 (OC) 的浓度。我们测试了以下假设：（i）所研究的苗圃中污染物的水平和分布不同，以及 ii）鱼类生长和身体状况（基于形态测量和肌肉 C:N 比）在污染物浓度较高的个体中较低。多变量分析表明，每个苗圃的 TME 和 OC 都有不同的污染物概况，证实了每个河口的特定污染，以及鲈鱼幼鱼积累的大量污染物。一些 TME 中浓度的增加与生长减少有关，和 TME 始终与较低的鱼体状况相关。OCs 的影响更难确定，这可能是由于操作限制（即对汇集的鱼的分析）与对比结果（即更高的生长和降低的身体状况）。总体而言，这项研究表明，化学污染物与野生鱼类早期生命阶段较低的鱼类生长和身体状况有关，如果在随后的年龄持续存在并与生存和/或繁殖成功率下降相关，这种影响可能会产生重大后果.