The temporal asynchronies in larvae production from different spawning areas are fundamental components for ensuring stability and resilience of marine metapopulations. Such a concept, named portfolio effect, supposes that diversifying larval dispersal histories should minimize the risk of recruitment failure by increasing the probability that at least some larvae successfully settle in nursery. Here, we used a reconstructive approach based on otolith chemistry to quantify the larval dispersal portfolio of the European seabass, , across six estuarine nursery areas of the northeast Atlantic Ocean. The analysis of natal and trajectory signatures indicated that larvae hatch in distinct environments and then dispersed in water masses featured by contrasting chemical signatures. While some trace elements appeared affected by temporal changes (Mn and Sr), others varied spatially during the larval stage but remained poorly affected by temporal fluctuation and fish physiology (Ba, Cu, Rb and Zn). We then proposed two diversity metrics based on richness and variations of chemical signatures among populations to reflect spatio-temporal diversity in natal origins and larval trajectories (i.e., estimates of dispersal portfolio). Along the French coast, the diversity estimates were maximum in nurseries located at proximity of offshore spawning sites and featured by complex offshore hydrodynamic contexts, such as the Mont St-Michel bay. Finally, our findings indicate that the dispersal portfolio was positively related with the local abundance of seabass juveniles, supporting the assumption that heterogeneity in dispersal history contributes to promote recruitment success in nurseries.

中文翻译：

---

使用耳石化学特征量化鲈鱼苗圃中的幼虫扩散组合

不同产卵区幼体生产的时间异步性是确保海洋集合种群稳定性和恢复力的基本组成部分。这种被称为组合效应的概念认为，幼虫传播历史的多样化应该通过增加至少一些幼虫在苗圃中成功定居的概率来最大限度地减少招募失败的风险。在这里，我们使用基于耳石化学的重建方法来量化欧洲鲈鱼幼虫在东北大西洋六个河口育苗区的扩散组合。对出生和轨迹特征的分析表明，幼虫在不同的环境中孵化，然后分散在具有对比化学特征的水团中。虽然一些微量元素似乎受到时间变化的影响（锰和锶），但其他微量元素在幼虫阶段在空间上发生变化，但受时间波动和鱼类生理的影响很小（Ba、Cu、Rb和Zn）。然后，我们根据种群间化学特征的丰富度和变化提出了两个多样性指标，以反映出生起源和幼虫轨迹的时空多样性（即传播组合的估计）。沿着法国海岸，位于近海产卵场附近且具有复杂的近海水动力环境（例如圣米歇尔山湾）的育苗场的多样性估计值最高。最后，我们的研究结果表明，扩散组合与当地鲈鱼幼鱼的丰度呈正相关，支持了扩散历史的异质性有助于促进苗圃招募成功的假设。