Peacock basses (genus Cichla) are a group of Amazonian predatory fishes that invaded many systems worldwide. Severe ecological impacts have been reported, but no study investigated the functional response of these fishes to variations in prey abundance, a crucial information to determine predator consumption and impact. In this study, we evaluated the functional response of the highly invasive Cichla kelberi toward prey species of different taxonomic groups, and compared it to the response of the wolf fish Hoplias malabaricus, a voracious predator used as baseline. We hypothesized that higher feeding rates drive the predatory impact of the invasive predator. Using a non-replacement experimental setup, we manipulated prey densities (fish and shrimp) in 1000-L mesocosm tanks to quantify the consumption response of each predator during 24 h. Both predators consumed more fish than shrimp, but C. kelberi consumed significantly more than H. malabaricus. We found that C. kelberi consistently displayed higher Type-II functional response than H. malabaricus toward both prey species. There was a non-significant effect of predator species on attack rates, but C. kelberi presented significantly lower handling time values and higher maximum feeding rates. Our findings provide empirical evidence that high individual consumption rates explain the predatory impact of the highly invasive C. kelberi, and predict strong effects on invaded communities.

中文翻译：

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比较功能反应预测高侵入性鱼类 Cichla kelberi 的捕食性影响

孔雀鲈（Cichla 属）是一群亚马逊掠食性鱼类，它们入侵了世界各地的许多系统。已经报告了严重的生态影响，但没有研究调查这些鱼类对猎物丰度变化的功能反应，这是确定捕食者消费和影响的关键信息。在这项研究中，我们评估了高度侵入性的 Cichla kelberi 对不同分类群的猎物物种的功能反应，并将其与狼鱼 Hoplias malabaricus 的反应进行了比较，狼鱼是一种用作基线的贪婪捕食者。我们假设较高的进食率会推动入侵性捕食者的掠食性影响。使用非替代实验装置，我们在 1000 升的中层水箱中操纵了猎物密度（鱼和虾），以量化每个捕食者在 24 小时内的消耗反应。两种捕食者消耗的鱼都比虾多，但 C. kelberi 消耗的鱼明显多于 H. malabaricus。我们发现 C. kelberi 对两种猎物物种始终表现出比 H. malabaricus 更高的 II 型功能反应。捕食者物种对攻击率的影响不显着，但 C. kelberi 的处理时间值显着降低，最大摄食率更高。我们的研究结果提供了经验证据，表明高个人消费率解释了高侵入性 C. kelberi 的掠夺性影响，并预测了对入侵社区的强烈影响。捕食者物种对攻击率的影响不显着，但 C. kelberi 的处理时间值显着降低，最大摄食率更高。我们的研究结果提供了经验证据，表明高个人消费率解释了高侵入性 C. kelberi 的掠夺性影响，并预测了对入侵社区的强烈影响。捕食者物种对攻击率的影响不显着，但 C. kelberi 的处理时间值显着降低，最大摄食率更高。我们的研究结果提供了经验证据，表明高个人消费率解释了高侵入性 C. kelberi 的掠夺性影响，并预测了对入侵社区的强烈影响。