Laboratório de Limnologia, Departamento de Ecologia, Instituto de Biologia, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, PO Box 68020, Rio de Janeiro, RJ, Brazil.
Department of Zoology and Biodiversity Research Centre, University of British Columbia, 6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada.
Glob Chang Biol. 2017 Feb;23(2):673-685. doi: 10.1111/gcb.13399. Epub 2016 Jul 21.
Climate change will alter the distribution of rainfall, with potential consequences for the hydrological dynamics of aquatic habitats. Hydrological stability can be an important determinant of diversity in temporary aquatic habitats, affecting species persistence and the importance of predation on community dynamics. As such, prey are not only affected by drought-induced mortality but also the risk of predation [a non-consumptive effect (NCE)] and actual consumption by predators [a consumptive effect (CE)]. Climate-induced changes in rainfall may directly, or via altered hydrological stability, affect predator-prey interactions and their cascading effects on the food web, but this has rarely been explored, especially in natural food webs. To address this question, we performed a field experiment using tank bromeliads and their aquatic food web, composed of predatory damselfly larvae, macroinvertebrate prey and bacteria. We manipulated the presence and consumption ability of damselfly larvae under three rainfall scenarios (ambient, few large rainfall events and several small rainfall events), recorded the hydrological dynamics within bromeliads and examined the effects on macroinvertebrate colonization, nutrient cycling and bacterial biomass and turnover. Despite our large perturbations of rainfall, rainfall scenario had no effect on the hydrological dynamics of bromeliads. As a result, macroinvertebrate colonization and nutrient cycling depended on the hydrological stability of bromeliads, with no direct effect of rainfall or predation. In contrast, rainfall scenario determined the direction of the indirect effects of predators on bacteria, driven by both predator CEs and NCEs. These results suggest that rainfall and the hydrological stability of bromeliads had indirect effects on the food web through changes in the CEs and NCEs of predators. We suggest that future studies should consider the importance of the variability in hydrological dynamics among habitats as well as the biological mechanisms underlying the ecological responses to climate change.
气候变化将改变降雨量的分布，对水生栖息地的水文动态产生潜在影响。水文稳定性可能是临时水生栖息地多样性的重要决定因素，影响物种的持久性和捕食对群落动态的重要性。因此，猎物不仅受到干旱引起的死亡率的影响，还受到捕食风险[非消耗性效应（NCE）]和捕食者实际捕食[消耗性效应（CE）]的影响。降雨引起的气候变化可能直接或通过改变水文稳定性，影响捕食者-猎物相互作用及其对食物网的级联效应，但这很少被探索，特别是在自然食物网中。为了解决这个问题，我们使用水箱凤梨及其水生食物网进行了现场实验，该食物网由捕食性蜻蜓幼虫、大型无脊椎动物猎物和细菌组成。我们在三种降雨情景（自然、少数大降雨事件和多次小降雨事件）下操纵蜻蜓幼虫的存在和捕食能力，记录凤梨中的水文动态，并研究其对大型无脊椎动物定殖、养分循环和细菌生物量和周转率的影响。尽管我们对降雨量进行了大规模的干扰，但降雨情景对凤梨的水文动态没有影响。因此，大型无脊椎动物的定殖和养分循环取决于凤梨的水文稳定性，而不受降雨量或捕食的直接影响。相比之下，降雨情景决定了捕食者对细菌的间接影响的方向，这是由捕食者的 CE 和 NCE 共同驱动的。这些结果表明，降雨量和凤梨的水文稳定性通过捕食者的 CE 和 NCE 的变化对食物网产生间接影响。我们建议未来的研究应该考虑栖息地水文动态变化的重要性以及生态响应气候变化的生物学机制。
