1. Data on ecological impacts of freshwater crayfish invasions in Africa are scarce but invasion history suggests the likelihood of negative implications for biodiversity.
2. To evaluate the potential for ecological impacts we describe the consumer‐resource dynamics of two established crayfish species (Cherax quadricarinatus and Procambarus clarkii) in comparison with the native trophic analogue, the freshwater crab Potamonautes perlatus preying upon Clarias gariepinus fry using comparative functional responses (FRs) and FR ratio (FRR). Experiments were conducted under dark and light conditions as well as low (19°C) and high (28°C) temperature treatments.
3. All three species exhibited potentially population destabilising Type II (hyperbolic) FRs towards prey, which was significantly higher in the dark than in the light. At low temperatures, P. perlatus exhibited the highest maximum feeding estimate although the FR curve was not significantly different from C. quadricarinatus at the highest prey densities. Both crayfish species had higher attack rates at both temperatures and consumed significantly more prey at the high temperature than P. perlatus. The FRR of both crayfish species at the high temperature treatment was higher than that of P. perlatus due to high attack rate and low handling parameters.
4. At 19°C, P. perlatus had a higher or negligible relative FR magnitude compared to P. clarkii and C. quadricarinatus respectively, which suggests some degree of biotic resistance at this temperature; however, this resistance is decreased at 28°C. Cherax quadricarinatus consistently had disruptive FR parameters across both temperatures.
5. Findings from this study represent an important step towards understanding the impacts of crayfish in Africa for public authorities and environmental managers. The two invasive crayfish species have the potential to exert greater per capita impacts on benthic prey communities in invaded systems as shown by their high FRs and FRRs. Furthermore, C. quadricarinatus is an emerging invader globally and our results provide evidence of potential for negative ecological impact regardless of thermal conditions. African countries and their respective environmental managers should therefore maximise efforts to prevent the introduction and spread of these invaders to conserve native biodiversity.

中文翻译：

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在较高温度下，有侵袭性的小龙虾的表现要好于Potamonautid螃蟹

1. 关于非洲淡水小龙虾入侵的生态影响的数据很少，但入侵历史表明对生物多样性有负面影响的可能性。
2. 为了评估潜在的生态影响，我们使用比较功能响应（FRs ）描述了两种成熟的小龙虾（Cherax quadricarinatus和Procambarus clarkii）与天然营养类似物淡水蟹Potamonautes perlatus捕食Clarias gariepinus鱼苗的消费者-资源动态。）和FR比（FRR）。实验是在黑暗和明亮的条件下以及低温（19°C）和高温（28°C）的条件下进行的。
3. 所有这三个物种都表现出潜在的种群破坏II型（双曲线）FRs朝向猎物的能力，在黑暗中明显高于在光照下。在低温下，尽管在最高猎物密度下FR曲线与C. quadricarinatus并无显着差异，但P. perlatus表现出最高的最大摄食量。两种小龙虾在两种温度下的攻击率均较高，且在高温下的捕食量远高于P. perlatus。由于高攻击率和低处理参数，两种小龙虾在高温处理下的FRR均高于P. perlatus。
4. 在19°C时，西班牙瓢虫的相对FR值分别高于克拉克假单胞菌和C. quadricarinatus，这表明在此温度下一定程度的生物抗性。但是，该电阻在28°C时降低。Cherax quadricarinatus在两个温度下始终具有破坏性的FR参数。
5. 这项研究的结果代表了朝着了解小龙虾在非洲对公共当局和环境管理者的影响迈出的重要一步。两种入侵小龙虾物种都有可能对入侵系统的底栖生物群落产生更大的人均影响，这是由于它们的高FR和FRR所显示。此外，C。quadricarinatus在全球范围内是一个新兴的入侵者，我们的研究结果提供了无论热条件如何都可能对生态造成负面影响的证据。因此，非洲国家及其各自的环境管理者应尽最大努力防止这些入侵者的传入和传播，以保护其自然生物多样性。