1. In novel communities, a rising number of new and emerging invasive species interact with resident species, some of which are non‐native themselves. We implemented an innovative trophic interaction framework for novel communities and quantified the interaction strength and impact potential of a truly novel species (marbled crayfish Procambarus virginalis) with a resident non‐native counterpart (spiny‐cheek crayfish Faxonius limosus). As prey, we used Dreissena mussels, which are non‐native as well and now hold a key position in many European and North American aquatic ecosystems.
2. For both crayfish species, we predicted functional responses based on a mechanistic model that we parameterised with a set of experimental observations of foraging behaviour and satiation. We compared these predicted functional responses to empirically observed responses. In addition, we incorporated behavioural traits such as aggression, activity, and boldness in the comparisons between the species and individuals to determine their influence on functional responses. We tested individuals from aquarium stocks as well as naturalised individuals from invaded water bodies.
3. Altogether, we performed 1,095 experiments with 26 individual crayfish. We found that per capita predation of spiny‐cheek crayfish exceeded that of marbled crayfish from aquaria and naturalised individuals. Functional responses differed between species and were mostly higher for spiny‐cheek crayfish males. Marbled crayfish, however, were more voracious and reached satiation more slowly. Consumption rates correlated with aggression for marbled crayfish and with an aggressive threat response for spiny‐cheek crayfish.
4. We conclude that spiny‐cheek crayfish can reach higher short‐term consumption rates than marbled crayfish, but both species probably do not substantially affect Dreissena mussel populations in the field. For marbled crayfish, high long‐term consumption, interspecific aggression, and reproduction rates can promote their establishment and spread. Risk assessments of these invaders should be improved by considering numerical responses, and different prey organisms and predators.

中文翻译：

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对个体水平功能反应的机械理解：作为模型生物的入侵小龙虾

1. 在新颖的社区中，越来越多的新出现的入侵物种与常驻物种相互作用，其中一些本身不是本地物种。我们为新颖的社区实施了一个创新的营养相互作用框架，并量化了一个真正的新物种（大理石小龙虾Procambarus virginalis）与常驻非本地对应物种（多刺小龙虾小龙虾Faxonius limosus）的相互作用强度和影响潜力。作为猎物，我们使用了德雷塞纳贻贝，它们也是非本地的，现在在许多欧洲和北美的水生生态系统中占有重要地位。
2. 对于这两种小龙虾，我们都基于一个机械模型来预测功能响应，该机械模型用一组关于觅食行为和饱食的实验观察参数化。我们将这些预测的功能反应与经验观察到的反应进行了比较。此外，我们在物种与个体之间的比较中纳入了攻击性，活动性和勇敢性等行为特征，以确定它们对功能反应的影响。我们测试了水族箱中的个体以及入侵水体中的归化个体。
3. 我们总共对26个小龙虾进行了1,095个实验。我们发现人均多刺小龙虾的捕食能力超过了来自水族馆和归化个体的大理石纹小龙虾的捕食能力。物种之间的功能反应有所不同，并且对于多刺小龙虾男性而言，其功能响应更高。然而，小龙虾更是贪婪的，饱足感也更慢。食用率与大理石化小龙虾的攻击性和棘手的小龙虾的激进威胁响应相关。
4. 我们得出的结论是，多刺小龙虾的短期食用率比大理石小龙虾要高，但是这两种物种都不会对田间的德雷塞纳贻贝种群产生实质性影响。对于大理石小龙虾，长期食用量高，种间侵略性和繁殖率高可促进其建立和传播。应通过考虑数字反应以及不同的猎物和捕食者来改善对这些入侵者的风险评估。