Predation is known to play a prominent role in maintaining ecosystem structure and functioning. Despite metals being known to potentially affect predation in aquatic ecosystems, few studies have been conducted, so far, with the aim of evaluating this interplay. In the present study, the effects of four metal salts (copper, cadmium, mercury, and manganese) on the feeding rates and food preference of the dragonfly Tramea cophisa and of the ostracod Chlamydotheca sp. were studied by performing laboratory ecotoxicity tests. Food preference was evaluated by offering four prey species to dragonfly nymphs and three to adult large ostracods. In general, the food preference of both predator species after being exposed to metal salts was not altered, compared with controls, but the feeding rate of T. cophisa decreased in comparison with controls, after exposure to each metal salt, except manganese. Contrastingly, predation rates of Chlamydotheca sp. increased after metal salt exposure. This difference in response can be explained by differences in life-history traits of these two organisms. Both species individuals preferred soft-bodied prey (Oligochaeta, Chironomidae) over water-dwelling crustaceans that are likely to be more difficult to prey upon. Tests evaluating the effects of metals and other chemicals on predation behavior may lead to a better understanding of biotic interactions that can be restricted by chemical stress, improving our understanding of possible food web disruptions underlying chemical stress.

众所周知，捕食在维持生态系统结构和功能方面发挥着重要作用。尽管已知金属可能会影响水生生态系统中的捕食行为，但迄今为止，很少有研究旨在评估这种相互作用。在本研究中，四种金属盐（铜、镉、汞和锰）对蜻蜓Tramea cophisa和介形虫Chlamydotheca的摄食率和食物偏好的影响sp. 通过进行实验室生态毒性试验进行研究。通过向蜻蜓若虫提供四种猎物和向成年大型介形动物提供三种猎物来评估食物偏好。一般来说，与对照相比，暴露于金属盐后两种捕食者物种的食物偏好没有改变，但与对照相比，在暴露于除锰之外的每种金属盐后，T. cophisa的摄食率降低。相比之下，衣藻的捕食率sp. 金属盐暴露后增加。这种反应的差异可以用这两种生物的生活史特征的差异来解释。两个物种个体都更喜欢软体猎物（Oligochaeta，摇蚊科），而不是可能更难捕食的水栖甲壳类动物。评估金属和其他化学物质对捕食行为的影响的测试可能会导致更好地了解可能受化学应激限制的生物相互作用，从而提高我们对潜在的化学应激潜在食物网破坏的理解。