Our understanding of functional roles of aquatic invertebrate taxa is still limited even for common species, although being crucial for explanations of patterns observed in natural communities. As only recently shown, the common native European amphipod Gammarus fossarum, traditionally treated as a shredder of leaf litter, shows predatory behaviour which may influence the composition of invertebrate assemblages. However, the evidence for the predation effect of G. fossarum on natural assemblages at the within‐site scale is still lacking. Therefore, we collected 50 quantitative samples of macroinvertebrates along with the important environmental variables within a heterogeneous calcareous spring fen. Using linear regression, we explored the relationships between the abundance of G. fossarum (separately adult and juvenile) and the abundance and number of taxa for two groups of invertebrates differing in their susceptibility to predation, (a) hard‐bodied taxa with protective body structures, such as shells and calcified cuticles, and (b) soft‐bodied taxa without those protections. We separated the effect of G. fossarum from that of environmental conditions using variation partitioning. Our results showed that only the abundance of soft‐bodied invertebrates was negatively correlated with the abundance of adult G. fossarum. However, the proportion of variation explained purely by predation (5.5%) was much lower than the one explained by the environment (33.8%). Both G. fossarum and soft‐bodied invertebrates were positively associated with organic matter. Although hard‐bodied invertebrates consisted of only a few taxa, they were more numerous than soft‐bodied invertebrates, and only environmental control was confirmed for them. Despite the limitations of the used correlative approach, we conclude that G. fossarum can significantly control the abundance of vulnerable taxa in natural assemblages. Its predatory effects, however, may be relatively low and easily confounded by the effect of environmental control.

中文翻译：

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杂食性镰刀rus捕食是否会影响大型无脊椎动物的小规模分布？石灰性春粉的案例研究

尽管对于解释自然界中观察到的模式至关重要，但我们对水生无脊椎动物类群功能作用的理解仍然有限，即使对于普通物种也是如此。正如最近所显示的那样，欧洲传统的两栖类双足类动物Gammarus fossarum传统上被当作切碎的叶子，显示出掠食性行为，可能会影响无脊椎动物组合的组成。但是，仍缺乏在场地规模上镰刀菌对自然组合的捕食作用的证据。因此，我们收集了50个定量的无脊椎动物定量样本以及重要的环境变量，这些环境变量均来自非均质的钙质春季spring。使用线性回归，我们探索了丰度之间的关系。G. fossarum（分别为成年和少年）以及两组无脊椎动物的捕食敏感性不同的分类单元的数量和数量，（a）具有保护性身体结构（如贝壳和钙化的表皮）的坚固分类单元，和（b ）没有这些保护的软体类群。我们使用变异分配法从环境条件中分离了镰刀菌的影响。我们的结果表明，只有软体无脊椎动物的丰富度与成年G. fossarum的丰富度呈负相关。但是，纯粹由捕食者解释的变异比例（5.5％）比环境所解释的变异比例（33.8％）低得多。两种都是和无脊椎动物与有机质呈正相关。尽管强硬无脊椎动物仅由几个分类单元组成，但它们比强硬无脊椎动物更多，并且仅对它们进行了环境控制。尽管使用了相关方法的局限性，我们得出的结论是，镰刀菌可以显着地控制自然组合中脆弱类群的数量。但是，它的掠食性影响可能相对较低，容易被环境控制的影响所混淆。