Sublethal effects of pesticides on predator-prey interactions in amphibians, 2008.

Increasing evidence suggests that contaminants in the environment can have important consequences on organismal interactions. While we have a good understanding of the lethal effects of contaminants on organisms, we have a weak understanding of how contaminants can affect organisms by altering the interactions that they have with other species in the community. Using tadpoles of two anuran species (Bullfrogs, Lithobates [Rana] catesbeianus; Green Frogs, L. clamitans), we investigated the effects of low nominal concentrations (1 and 10 ppb) of two pesticides (malathion and endosulfan) on tadpole activity and survival when exposed to four predator treatments (no predators; water bugs, Belostoma flumineum; newts, Notophthalmus viridescens; and dragonfly larvae, Anax junius). In both anuran species, adding predators reduced tadpole activity and survival, with increasing rates of mortality occurring with water bugs, newts, and dragonflies, respectively. Additionally, the highest concentration of endosulfan caused tadpole mortality after 48 hrs. Most significant, tadpole species also experienced interactive effects of predators and pesticides on survival after 48 hrs. In Bullfrog treatments, all predators reduced the amount of tadpole mortality when exposed to endosulfan. In Green Frogs, additive negative effects occurred, except that newts increased the tadpole mortality when exposed to endosulfan. Our findings illustrate that pesticide effects on predator–prey interactions are often complex and have the potential to alter aquatic community composition.

越来越多的研究证据表明，环境污染物可对生物间的相互作用产生显著影响。尽管学界对污染物导致生物死亡的致死效应已有较为充分的认知，但对于污染物如何通过改变生物与群落内其他物种的相互作用来影响生物本身，目前的理解仍相对薄弱。本研究以两种无尾目两栖动物的蝌蚪为实验材料：牛蛙（Bullfrogs，Lithobates [Rana] catesbeianus）与绿蛙（Green Frogs，L. clamitans），设置了马拉硫磷（malathion）和硫丹（endosulfan）两种农药的低标称浓度（1 ppb与10 ppb）处理，并搭配四种捕食者处理组（无捕食者；负子蝽Belostoma flumineum、红腹蝾螈Notophthalmus viridescens以及蜻蜓幼虫Anax junius），探究了农药暴露对蝌蚪活动能力与存活率的影响。实验结果显示，两种无尾目两栖动物的蝌蚪在捕食者存在的情况下，其活动能力与存活率均显著降低，蝌蚪死亡率依次随负子蝽、红腹蝾螈、蜻蜓的捕食压力升高而上升。此外，最高浓度的硫丹可在暴露48小时后引发蝌蚪死亡。尤为关键的是，两种蝌蚪的存活率均受到捕食者与农药的交互作用影响：在牛蛙实验组中，所有捕食者处理均会削弱硫丹暴露导致的蝌蚪死亡率；而在绿蛙实验组中，除红腹蝾螈处理组会加剧硫丹暴露下的蝌蚪死亡率外，其余处理均呈现出农药与捕食者的协同负面效应。本研究结果表明，农药对捕食者-猎物相互作用的影响往往较为复杂，且具备改变水生群落物种组成的潜在可能。