Abstract Coastal ecosystems are subject to a wide variety of abiotic variation including seasonal fluctuations and hydrodynamic disturbance, which can influence species distributions. Additionally, introductions of invasive species are creating biotic pressures within coastal ecosystems, which can influence biological interactions. With the recent development of combining comparative functional responses, prey switching and biotic resistance theory in invasion ecology, invasion success and ecological impacts of invaders can be better quantified. Further, the incorporation of environmental contexts with these approaches allows predictions of invader success under a range of ecological scenarios. We examined the functional responses and prey switching propensities of the native European green crab, Carcinus maenas (Linnaeus, 1758), towards native blue mussels, Mytilus edulis (Linnaeus, 1758), and invasive Pacific oysters, Crassostrea (Magallana) gigas (Thunberg, 1793), under the abiotic contexts of season (winter vs summer) and hydrodynamic disturbance level (high vs low). In general, when each prey species was offered separately, C. maenas maximum feeding rates were higher towards native M. edulis compared to invasive C. gigas. In addition, handling times were lower, and thus maximum feeding rates were higher, in summer compared to winter. Hydrodynamic disturbance level had no significant influence on handling times or maximum feeding rates towards either prey species. When prey species were offered simultaneously, C. maenas disproportionately consumed native M. edulis over invasive C. gigas irrespective of proportional availability. In addition, increased hydrodynamic disturbance further increased the disproportionate consumption of M. edulis over C. gigas. We thus demonstrate that C. maenas offers little biotic resistance to invasions of C. gigas under a range of abiotic contexts, and indeed some of these contexts may exacerbate the invasion. We suggest that combined functional response and prey switching studies provide a wealth of information regarding invasion success and biotic resistance towards invasive species under environmental variation.

中文翻译：

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无论季节或水动力干扰如何，对入侵双壳类动物都缺乏生物抗性

摘要 沿海生态系统受到各种非生物变异的影响，包括季节性波动和水动力扰动，这会影响物种分布。此外，入侵物种的引入正在沿海生态系统内造成生物压力，这会影响生物相互作用。随着最近在入侵生态学中结合比较功能反应、猎物转换和生物抗性理论的发展，可以更好地量化入侵者的入侵成功和生态影响。此外，将环境背景与这些方法结合起来可以预测入侵者在一系列生态场景下的成功。我们检查了欧洲本土绿蟹 Carcinus maenas (Linnaeus, 1758) 的功能反应和猎物转换倾向，在季节（冬季与夏季）和水动力干扰水平（高与低）的非生物背景下，对原生蓝贻贝、贻贝（Linnaeus，1758 年）和侵入性太平洋牡蛎、巨牡蛎（Magallana）（Thunberg，1793 年）的影响。一般来说，当单独提供每种猎物时，与入侵的 C. gigas 相比，C. maenas 对本地 M. edulis 的最大摄食率更高。此外，与冬季相比，夏季处理时间较短，因此最大饲喂率较高。水动力扰动水平对处理时间或对任一猎物的最大摄食率没有显着影响。当同时提供猎物物种时，C. maenas 不成比例地消耗本地 M. edulis 而不是入侵的 C. gigas，而不管比例可用性如何。此外，增加的水动力干扰进一步增加了 M. edulis 对 C. gigas 的不成比例的消耗。因此，我们证明 C. maenas 在一系列非生物环境下对 C. gigas 的入侵几乎没有生物抗性，并且确实其中一些环境可能会加剧入侵。我们建议结合功能反应和猎物转换研究提供了大量关于环境变化下入侵成功和对入侵物种的生物抗性的信息。