Human-mediated salinity increases are occurring in freshwaters globally, with consequent negative effects on freshwater biodiversity. Salinity comprises multiple anions and cations. While total concentrations are typically used to infer effects, individual ion concentrations and ion ratios are critical in determining effects. Moreover, estimates of toxicity from single-species laboratory tests, may not accurately predict relative effects on populations and communities. Here, we compared salinity increases from synthetic marine salts and sodium bicarbonate in an outdoor mesocosm experiment in southeastern Australia. We found different effects of salt types on stream macroinvertebrates at the population and community levels, where similar effects were predicted from single-species laboratory tests. Our results caution against the use of single-species laboratory-derived toxicological data to predict both environmentally safe salinity levels and the relative effects of different salt sources on freshwater biodiversity.

中文翻译：

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单一物种急性致死毒性试验不能预测两种盐度类型的相对种群和群落影响

人类介导的盐度增加正在全球范围内的淡水中发生，从而对淡水生物多样性产生负面影响。盐度包括多种阴离子和阳离子。虽然总浓度通常用于推断效果，但单个离子浓度和离子比率对于确定效果至关重要。此外，来自单一物种实验室测试的毒性估计可能无法准确预测对种群和社区的相对影响。在这里，我们在澳大利亚东南部的室外中观实验中比较了合成海盐和碳酸氢钠的盐度增加。我们发现了盐类在种群和群落层面对溪流大型无脊椎动物的不同影响，从单一物种实验室测试中预测了类似的影响。