Centre for Applied Water Science, Institute for Applied Ecology, University of Canberra, Canberra, Australia.
Centre for Applied Water Science, Institute for Applied Ecology, University of Canberra, Canberra, Australia; New South Wales Department of Climate Change, Energy, the Environment and Water, PO Box 53, Wollongong, NSW 2500, Australia.
Sci Total Environ. 2024 Nov 25;953:176082. doi: 10.1016/j.scitotenv.2024.176082. Epub 2024 Sep 5.
Freshwater ecosystems are being degraded by a wide range of stressors resulting from human activities. Various structural and functional metrics or indices are used to assess the 'health' or condition of riverine ecosystems. It is uncertain if structural or functional metrics or indices respond to different stressors and whether some are more responsive to stressors in general. Here we conducted a multi-study synthesis, similar to a meta-analysis, across four independent outdoor mesocosm experiments involving the manipulation of various chemical stressors - two types of salinity (synthetic marine salts (SMS) and sodium bicarbonate), two insecticides (malathion and sulfoxaflor), increased nutrients (N and P), increased sedimentation and two combinations of stressors (1: malathion, nutrients and sedimentation, 2: sulfoxaflor, nutrients and sedimentation). We compare the effects of these singular or multiple stressors on stream macroinvertebrate community structure, and Eucalyptus camaldulensis leaf litter breakdown rates by microbes and total (microbes and invertebrates). Macroinvertebrate communities were adversely affected by the two sets of multiple stressors, SMS, and both insecticides yet, and in contrast to several published studies, both microbial and total leaf litter was unaffected. Nutrients and sodium bicarbonate, increased breakdown rates or had a unimodal 'Ո' shaped response, with maxima at intermediate levels. Sedimentation by fine sand, however, decreased total leaf litter breakdown, while not affecting microbial leaf litter breakdown. Divergent responses between the effects of stressors on leaf litter breakdown rates that we observed and those in the literature may be caused by multiple mechanisms, including differences between communities, functional redundancy and differences in stressor magnitude and interactions with other (unknown) variables.
淡水生态系统正受到人类活动造成的各种压力的破坏。各种结构和功能指标或指数被用于评估河流生态系统的“健康”或状况。目前还不确定结构或功能指标或指数是否对不同的压力源有反应，以及是否有些指标或指数对压力源更敏感。在这里，我们进行了一项多研究综合分析，类似于荟萃分析，涉及四个独立的户外中观实验，涉及各种化学压力源的操纵 - 两种类型的盐度（合成海水盐（SMS）和碳酸氢钠），两种杀虫剂（马拉硫磷和磺酰氟），增加养分（N 和 P），增加沉积物和两种压力源的组合（1：马拉硫磷，养分和沉积物，2：磺酰氟，养分和沉积物）。我们比较了这些单一或多种压力源对溪流大型无脊椎动物群落结构以及微生物和总（微生物和无脊椎动物）对桉树叶片分解率的影响。大型无脊椎动物群落受到这两组多种压力源、SMS 和两种杀虫剂的不利影响，但与几项已发表的研究相反，微生物和总叶片都没有受到影响。养分和碳酸氢钠增加了分解率，或者呈现出单峰“Ո”形反应，在中等水平时达到最大值。然而，细砂的沉积减少了总叶片的分解，而不影响微生物叶片的分解。我们观察到的压力源对叶片分解率的影响与文献中的影响之间的分歧反应可能是由多种机制引起的，包括群落之间的差异、功能冗余以及压力源大小和与其他（未知）变量的相互作用的差异。
