Data from: Effects of elevated carbon dioxide on male and female behavioural lateralisation in a temperate goby

Behavioural abnormality in fishes has been proposed as a significant threat of the increasing levels of carbon dioxide occurring in the oceans. Negative effects of elevated CO2 have been reported for behaviours such as predator-prey interactions, foraging, hearing and behavioural lateralisation. Importantly, the effects vary greatly both within and between species, and some recent studies have shown minimal effects of CO2 on behaviour. Whether the effect of CO2 also varies between males and females is however virtually unexplored. According to resource allocation theory, females are expected to be more sensitive to elevated CO2, meaning that non-sex specific studies may overlook ecologically important differences between the sexes. In this study, we investigated the possible differences between males and females in their response to elevated CO2 by performing behavioural lateralisation tests in adult temperate two-spotted gobies Gobiusculus flavescens. We found that the strength of the side bias (absolute lateralisation) was unaffected by the CO2 treatment, and there was no difference between males and females. The control fish were slightly right-biased in their behavioural asymmetry (mean relative lateralisation of 14). Exposure to high CO2 affected this pattern, such that treated fish were slightly left biased (mean relative lateralisation of -10), regardless of their sex. The same results were obtained yet again when the study was repeated during a second year. We discuss our results in light of the great variation in lateralisation that has been reported to depend on variables such as species, ecological settings and environmental factors.

海洋中不断升高的二氧化碳浓度所带来的一项重大威胁，便是引发鱼类行为异常。已有研究表明，二氧化碳浓度升高会对鱼类的多种行为造成负面影响，包括捕食者-猎物互作、觅食、听觉以及行为偏侧化（behavioural lateralisation）。值得注意的是，这类影响在物种内部和物种间均存在显著差异，近期部分研究甚至显示二氧化碳对鱼类行为几乎无影响。然而，二氧化碳的影响是否存在雌雄个体差异，目前几乎尚未有相关研究涉足。根据资源分配理论（resource allocation theory），雌性个体对二氧化碳浓度升高的敏感性预计会更高，这意味着未区分性别的研究可能会忽略雌雄间具有重要生态学意义的差异。本研究以成年温带双斑虾虎鱼（Gobiusculus flavescens）为实验对象，通过行为偏侧化测试，探究了雌雄个体对二氧化碳浓度升高的响应是否存在差异。研究结果显示，侧偏强度（绝对偏侧化，absolute lateralisation）并未受到二氧化碳处理的影响，且雌雄个体间无显著差异。对照组鱼类的行为不对称性表现出轻微的右偏倾向，平均相对偏侧化（relative lateralisation）值为14。而经高浓度二氧化碳处理的实验组鱼类则呈现出轻微的左偏倾向，平均相对偏侧化值为-10，且该效应不受性别影响。次年重复开展该实验时，同样得到了一致的研究结果。我们结合已报道的、受物种、生态环境及其他环境因素影响的偏侧化现象的巨大差异，对本研究结果展开了讨论。