Department of Aquaculture and Fish Biology, Hólar University College, Saudárkrókur, Iceland.
Ifremer, Laboratoire Ressources Halieutiques, Centre Manche Mer du Nord, Boulogne-sur-Mer, France.
PLoS One. 2019 Mar 27;14(3):e0213061. doi: 10.1371/journal.pone.0213061. eCollection 2019.
Temperature and individual egg size have been long studied in the development of fishes because of their direct effects on individual fitness. Here we studied the combined effects of three important factors for fish development, i.e. egg size, social environment and water temperature. Arctic charr (Salvelinus alpinus), a coldwater fish known to be phenotypically plastic, was used to investigate how these factors may affect growth and foraging behaviour of juvenile fish in a benign environment. We accounted for the social environment during early development by comparing fish raised in groups and in isolation. We examined the effect of egg size and a 2 °C difference on foraging behaviour, activity and growth a few weeks after first feeding. Growth trajectories of fish originating from large and small eggs were similar within each temperature: larger fish coming large eggs were at all time larger than smaller fish. There was no indication that small fish raised at a higher temperature grew faster than larger fish raised at a lower temperature. A 2 °C difference in temperature affected the behaviour of fish differently according to body size and/or social context. The foraging probability difference between fish raised in groups and fish briefly isolated was higher at 4.5 °C than at 6.5 °C for both size fish. Finally, there was no repeatability in foraging behaviour and mobility for isolated individuals. These results highlight the importance of small changes in temperature when evaluating growth and behaviour of fishes, and reveal the importance of considering the interaction of temperature with other factors, e.g. individual size and social environment, especially at early stages of development in fishes. We discuss these findings in the context of rapid changes in temperature and how temperature and its interaction with other factors may affect the phenotypes, ecology and evolution of coldwater fishes.
温度和个体卵大小一直是鱼类发育研究的重点，因为它们直接影响个体适应性。在这里，我们研究了三个对鱼类发育很重要的因素，即卵大小、社会环境和水温的综合影响。北极红点鲑（Salvelinus alpinus）是一种表型可塑性很强的冷水鱼，用于研究这些因素如何影响在良性环境中幼鱼的生长和觅食行为。我们通过比较群体饲养和单独饲养的方式来考虑早期发育的社会环境。我们考察了卵大小和 2°C 的差异对首次摄食后几周内觅食行为、活动和生长的影响。来自大卵和小卵的鱼在每个温度下的生长轨迹相似：来自大卵的大鱼始终比来自小卵的小鱼大。没有迹象表明，在较高温度下饲养的小鱼比在较低温度下饲养的大鱼生长得更快。2°C 的温度差异根据体型和/或社会环境对鱼类的行为有不同的影响。对于两种体型的鱼来说，在 4.5°C 时，群体饲养的鱼和短暂隔离的鱼之间的觅食概率差异比在 6.5°C 时更大。最后，单独饲养的鱼的觅食行为和移动性没有可重复性。这些结果强调了在评估鱼类的生长和行为时，小的温度变化的重要性，并揭示了考虑温度与其他因素（如个体大小和社会环境）相互作用的重要性，尤其是在鱼类发育的早期阶段。我们在温度快速变化的背景下讨论了这些发现，以及温度及其与其他因素的相互作用如何影响冷水鱼类的表型、生态和进化。
