水生生态环境中捕食信息素的生态学效应

捕食信息素是捕食者释放的,能够引发猎物反捕食反应的化学信号。在水生生态系统中,捕食信息素在捕食者和猎物之间信息传递及协同进化过程中发挥着重要的作用,其生态学效应在国际上受到广泛关注。捕食信息素的来源有多种形式,研究中常使用养殖过捕食者的水溶液作为捕食信息素的来源。捕食信息素的作用效果受到捕食者和猎物的种类、信息素的浓度、观察的指标等多方面因素的影响。捕食信息素可以对水生生物的行为、形态和生活史特征等方面造成影响。水生生物通过感知捕食信息素来提前预知潜在的被捕食风险,并作出适应性调整,以降低被捕食的风险。在某些情况下,捕食信息素可以与污染物产生交互作用,从而干扰污染物对水生生物的毒性。对水生环境中捕食信息素的研究现状做了综述,介绍了当前对捕食信息素来源和理化性质等本质问题的认识,总结捕食信息素对水生生物行为、形态和生活史特征的影响,以及捕食信息素对污染物毒性的干扰,并分析了这一研究领域尚存在的困难和今后的研究方向。加强对捕食信息素的研究,将为解析水生环境中捕食者和猎物的生态关系提供新依据。

Ecological effects of predator chemical cues in aquatic ecosystem

Predator chemical cues are chemical signals released by predators that inform potential prey of the presence of predators. Predator cues allow prey to detect and evade predators from a distance. In aquatic ecosystem, predator chemical cues have been shown to play an important role in information transmission and evolutionary race between prey and predator. The effect of predator cues on aquatic organisms has received increased attention recently. This paper summarized the current understanding on the nature of predator chemical cues and the ecological effects of predator chemical cues on the behavior, morphology, and life-history of aquatic organisms. Recent work on the effects of predator cues on disturbing the toxicity of contaminants was also reviewed. Predator chemical cues origin from the skin exudates, faeces, or injured tissue of predators. It was sometimes confused with conspecific cues since conspecific cues could induce similar responses. Studies examining the effects of predator cues often used predator conditioned water as the sources of predator chemical cues. Although knowledge about the chemical nature of predator chemical cues is still scarce, considerable advances have been made, especially for the identification of cues inducing anti-predator defenses in ciliates and cues originated from fishes. It was found that the effects of predator cues are associated with predator species, predator's diet, concentration of cues, and many other factors. The identification and isolation of predator cues is an important step towards understanding the nature and ecological effects of predator cues. Numerous studies have shown that predator-released chemical cues could induce behavioral, morphological and life-historical anti-predator responses in preys. Behavioral responses to predator cues include avoidance of the area where cues is detected, decreased activity levels or freezing, and increased use of shelter. Behavioral responses of prey to predator cues have been found in cladocerans, gastropods, fishes, and amphibians. Morphological defenses have been found in a wide range of aquatic taxa, including algae, protozoans, rotifers, cladocerans, gastropods, insects, fishes and amphibians. Among them Chaoborus-induced morphological defense in Daphnia have received the most attention. Life-history responses to predator cues were mainly studied in cladocerans and amphibians, and the responses include adaptive changes in life-history switch points (such as timing of hatching and metamorphosis), longevity and reproduction. The anti-predation responses make prey less vulnerable to predation, and is believed to cause costs that are saved in the absence of predators. Interestingly, it was found that predator cues may interact with contaminants and influence their toxicity to the survival, growth, and life-history of prey. The interaction may be influenced by the sources of predator cues, classes of contaminants and their concentrations, endpoints of prey, and so on. These findings indicate that predatory stress plays an important role in the process of how contaminants exert their effects within the aquatic environment. The mechanisms of interaction between predator cues and contaminants are still unclear. Although considerable progress has been made, several key questions in this area remain. Future studies are needed to explore the chemical nature of predator cues and to examine the signal transmission process in predator-prey interaction. Knowledge of the chemistry and signal transmission process of predator chemical cues may improve our ability to design meaningful experiments, so as to gain better understanding on predator-prey interaction in aquatic ecosystem.