Salinisation has direct and detrimental physiological effects on freshwater organisms, yet little is known about its indirect effects. Here, we present a study that investigated the primary and secondary effects of salinisation on aquatic macroinvertebrates. We analysed macroinvertebrate samples from nine sites in river Wipper, Germany against nine stressor variables (water quality, salinisation, hydromorphological degradation). A Principal Component Analysis showed water quality deterioration and physical habitat degradation to constitute the main stressor gradients. Two macroinvertebrate community metrics (index of general degradation and percent Ephemeroptera-Plecoptera-Trichoptera specimens) revealed strong and significant positive correlations with water quality, but only weak and insignificant positive correlations with hydromorphological quality. High-resolution temporal measurements revealed notable oxygen deficits at a salinised and macrophyte-rich site that was dominated by the salt-tolerant macrophyte species Stuckenia [Potamogeton] pectinata (L.) Börner. At the site, oxygen levels frequently dropped below 6 mg/L during nighttime, suggesting an interaction of osmoregulatory stress (through salinisation) and respiratory stress (through plant mitochondrial respiration) that is caused by the mass development of a salt-tolerant macrophyte species. This biologically driven interaction of direct and indirect salinisation effects adds another level of complexity to the influence of multiple stressors in lotic systems and requires consideration in river management and restoration.

盐碱化对淡水生物有直接和有害的生理影响，但对其间接影响知之甚少。在这里，我们提出了一项研究，调查盐渍化对水生大型无脊椎动物的主要和次要影响。我们根据九个压力源变量（水质、盐碱化、水形态退化）分析了来自德国维珀河九个地点的大型无脊椎动物样本。主成分分析表明，水质恶化和自然栖息地退化构成了主要的压力源梯度。两个大型无脊椎动物群落指标（一般退化指数和蜉蝣目-蜉蝣目-毛翅目标本百分比）揭示了与水质强烈而显着的正相关，但与水形态质量只有微弱且不显着的正相关。高分辨率时间测量显示，在以耐盐大型植物物种为主的盐碱化和大型植物丰富的地点存在明显的缺氧Stuckenia [ Potamogeton ] pectinata (L.) Börner。在该地点，夜间氧气水平经常降至 6 毫克/升以下，这表明渗透压调节压力（通过盐碱化）和呼吸压力（通过植物线粒体呼吸）的相互作用是由耐盐大型植物物种的大量发育引起的。这种由生物驱动的直接和间接盐碱化效应的相互作用为流域系统中多重压力因素的影响增加了另一个层次的复杂性，需要在河流管理和恢复中加以考虑。