Correa-Araneda Francisco, Basaguren Ana, Abdala-Díaz Roberto T, Tonin Alan Mosele, Boyero Luz
Laboratory of Ecotoxicology Department of Zoology Faculty of Natural and Oceanographic Sciences University of Concepción Concepción Chile.
Department of Plant Biology and Ecology Faculty of Science and Technology University of the Basque Country (UPV/EHU) Leioa Spain.
Ecol Evol. 2017 Jun 2;7(14):5103-5110. doi: 10.1002/ece3.3094. eCollection 2017 Jul.
The replacement of native forests by exotic tree monocultures, such as those of , decreases the quality of leaf litter inputs to streams and often reduces riparian cover, which can elevate water temperature. The combined effects of these stressors on the survival and performance of detritivores may be important, as detritivore species loss leads to reduced litter breakdown, a key ecosystem process. Potential loss of cased caddisfly larvae is of particular concern because they are the predominant detritivores in many streams, they are sensitive to warming, and they expend energy on building and carrying their cases, which may be an added burden under times of stress. In a microcosm experiment, we tested whether (i) poor-quality litter impaired case construction by larvae of (due to preferential allocation of the scarcer available energy to larval fitness) compared to high-quality litter; (ii) whether this effect was enhanced by higher temperatures (15 vs. 10°C) resulting in faster metabolism and greater energy expenditure; but (iii) reduced in the presence of chemical cues from a predatory fish (due to greater investment in more protective cases). We found that had lethal and sublethal effects on larval caddisflies, increasing mortality, reducing growth, and impairing case construction, compared to larvae fed . Temperature did not reinforce the effects of exotic litter on case construction, but predator chemical cues triggered the construction of more protective cases (i.e., longer and better cemented) despite the lower resource quality, providing evidence for environmentally mediated resource-allocation tradeoffs.
外来单一树种人工林取代原生森林，例如那些[具体树种未提及]的人工林，会降低溪流中落叶输入的质量，并常常减少河岸植被覆盖，进而可能导致水温升高。这些压力源对碎屑食性动物的生存和表现的综合影响可能很重要，因为碎屑食性物种的丧失会导致凋落物分解减少，而凋落物分解是一个关键的生态系统过程。带壳毛翅目幼虫的潜在损失尤其令人担忧，因为它们是许多溪流中的主要碎屑食性动物，对变暖敏感，并且会消耗能量来建造和携带它们的外壳，这在压力时期可能会增加负担。在一个微观实验中，我们测试了：（i）与高质量的[具体树种未提及]落叶相比，低质量的[具体树种未提及]落叶是否会损害[具体毛翅目幼虫种类未提及]幼虫的外壳建造（由于将更稀缺的可用能量优先分配给幼虫适应性）；（ii）更高的温度（15摄氏度与10摄氏度）是否会增强这种影响，导致新陈代谢加快和能量消耗增加；但是（iii）在存在捕食性鱼类的化学信号时这种影响是否会减弱（由于在更具保护性的外壳上投入更多）。我们发现，与喂食[具体树种未提及]落叶的幼虫相比，[具体树种未提及]落叶对毛翅目幼虫有致死和亚致死影响，增加了死亡率，降低了生长速度，并损害了外壳建造。温度并没有增强外来落叶对外壳建造的影响，但捕食者化学信号触发了建造更具保护性的外壳（即更长且粘结更好），尽管资源质量较低，这为环境介导的资源分配权衡提供了证据。
