Ocasio-Torres Maria E, Crowl Todd A, Sabat Alberto M
Department of Natural Sciences, Ana G. Mendez University, Gurabo, Puerto Rico, United States of America.
Southeast Environmental Research Center, Florida International University, Miami, FL, United States of America.
PeerJ. 2021 Mar 12;9:e11011. doi: 10.7717/peerj.11011. eCollection 2021.
Prey can alter their behavior when detecting predator cues. Little is known about which sensory channel, number of channels, or the interaction among channels that shrimp species use to evaluate the threat from predators. The amphidromous shrimp has an induced defense, an elongated rostrum, where predatory fishes are present. We sought to test if kairomones or visual cues when presented singly from fish either eating flakes or shrimp, had more effect on altering the temporal feeding and refuge use patterns of long-rostrum (LR) . We were also interested in elucidating potential interactions among cues when presented simultaneously in different combinations (kairomones + visual + mechanosensory, kairomones + alarm + visual, kairomones + alarm, kairomones + visual) on the same response variables. We expected that when presented alone kairomones will significantly increase refuge use and decrease foraging, particularly late at night, in comparison to visual cues alone, and that multiple cues when presented simultaneously will further increase refuge use and decrease foraging at night.
We exposed shrimp to individual or multiple cues from the predatory fish mountain mullet, . We examined shrimp behavior with respect to refuge use and foraging activity during four time periods (after sunset, nighttime, sunrise, and sunset) in a 24-hour period.
Shrimp presented fish visual and chemical cues singly did not differ from one another but differed from control shrimp (no cues) with respect to refuge use or foraging. The number of shrimp using refuge in the treatment with most cues (KVM: kairomones+ visual + mechanosensory) was higher than in all the treatments with less cues. A significant decline in foraging was observed when multiple cues were presented simultaneously. The highest number of shrimp foraged one hour after sunset and at nighttime. A significant interaction was observed between cue treatments and time periods, with shrimp in the KVM treatment foraging less and using more refuge late at night and at sunrise than shrimp in other treatments or time periods.
The observation that fish chemical and visual cues when presented singly produced similar refuge use and foraging patterns was contrary to expectation and suggests that visual and chemical cues, when presented alone, provide redundant information to with regards to predation threat. The significant increase in refuge use and reduction in foraging observed in the KVM treatment suggest multimodal signal enhancement in the perception of threat. This makes evolutionary sense in "noisy" environments, such as streams, where detection, localization, and intention of predators is much improved when cues are received through multiple sensory channels.
猎物在察觉到捕食者线索时会改变其行为。对于虾类利用哪些感官通道、通道数量或通道之间的相互作用来评估来自捕食者的威胁，我们知之甚少。在有掠食性鱼类存在的地方，溯河性虾类有一种诱导防御机制，即延长的吻部。我们试图测试，当单独呈现来自正在吃薄片饲料或虾的鱼类的信息素或视觉线索时，对长吻（LR）虾的觅食时间和避难所使用模式的改变是否有更大影响。我们还感兴趣于阐明当以不同组合（信息素 + 视觉 + 机械感觉、信息素 + 警报 + 视觉、信息素 + 警报、信息素 + 视觉）同时呈现线索时，对相同反应变量的潜在相互作用。我们预计，与单独的视觉线索相比，单独呈现信息素时，避难所使用将显著增加，觅食将减少，尤其是在深夜；同时呈现多种线索时，夜间避难所使用将进一步增加，觅食将减少。
我们让虾暴露于来自掠食性鱼类多鳞四指马鲅的单个或多个线索中。我们在24小时的四个时间段（日落后、夜间、日出和日落）内，研究了虾在避难所使用和觅食活动方面的行为。
单独呈现鱼类视觉和化学线索时，虾之间没有差异，但在避难所使用或觅食方面与对照虾（无线索）不同。在线索最多的处理组（KVM：信息素 + 视觉 + 机械感觉）中使用避难所的虾的数量高于线索较少的所有处理组。同时呈现多种线索时，观察到觅食显著减少。日落一小时后和夜间觅食的虾数量最多。线索处理和时间段之间观察到显著的相互作用，与其他处理或时间段的虾相比，KVM处理组的虾在深夜和日出时觅食较少，使用避难所较多。
单独呈现鱼类化学和视觉线索时产生相似的避难所使用和觅食模式这一观察结果与预期相反，表明单独呈现视觉和化学线索时，就捕食威胁而言，向虾提供了冗余信息。在KVM处理组中观察到的避难所使用显著增加和觅食减少表明在威胁感知中存在多模态信号增强。这在“嘈杂”的环境中，如溪流中，具有进化意义，在这种环境中，当通过多个感官通道接收线索时，对捕食者的检测、定位和意图的感知会大大改善。
