An increasing threat to local, native freshwater mussels (Unionida)—an ecologically important but globally alarmingly declining group—is the invasion by exotic bivalves. The Enemy Release Hypothesis predicts that introduced species should benefit from enemy-mediated competition because they are less likely to be harmed by natural enemies, such as parasites, than their native competitors. We investigated within-site differences in parasitism between sympatric native (tot. five spp.) and invasive (tot. three spp.) bivalves in eight northern European waterbodies, which harboured totally 15 parasite taxa. In paired comparisons using within-site averages, the mean number of parasite species in the native bivalves was 2.3 times higher, and the sum of parasite prevalences 2.4 times higher, than in the invasive bivalves. This may lead to enemy-mediated competitive release of invaders and contribute to the success of invasive freshwater bivalves, in general. However, while the invasive clam Corbicula fluminea was completely free from parasites, parasite parameters of the other invader, Sinanodonta woodiana, were relatively high, indicating that the role of parasites can be invader-specific and urges further research. Understanding the factors affecting success of freshwater bivalve invasions, such as parasitism, can aid invasion control and conservation of local, native (endangered) bivalves.

中文翻译：

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本地和入侵淡水双壳类动物同域种群中的寄生虫

外来双壳类动物的入侵对当地原生淡水贻贝（一种具有生态重要性但在全球范围内急剧减少的物种）日益增加的威胁。Enemy Release Hypothesis 预测，引入的物种应该从敌人介导的竞争中受益，因为与它们的本地竞争对手相比，它们不太可能受到寄生虫等天敌的伤害。我们调查了 8 个北欧水体中同域本地（总共 5 种）和入侵（总共 3 种）双壳类动物之间寄生的现场差异，这些水体总共包含 15 个寄生虫分类群。在使用站点内平均值的配对比较中，本地双壳类动物的寄生虫物种平均数量是入侵双壳类动物的 2.3 倍，寄生虫患病率总和高 2.4 倍。这可能导致敌人介导的入侵者竞争性释放，并有助于入侵淡水双壳类动物的成功，一般来说。然而，虽然入侵蛤蜊 Corbicula fluminea 完全没有寄生虫，但另一种入侵者 Sinanodonta woodiana 的寄生虫参数相对较高，表明寄生虫的作用可以是入侵者特异性的，并敦促进一步研究。了解影响淡水双壳类动物入侵成功的因素，例如寄生性，有助于控制和保护当地的本地（濒危）双壳类动物。表明寄生虫的作用可以是特定于入侵者的，并敦促进一步研究。了解影响淡水双壳类动物入侵成功的因素，例如寄生性，有助于控制和保护当地的本地（濒危）双壳类动物。表明寄生虫的作用可以是特定于入侵者的，并敦促进一步研究。了解影响淡水双壳贝类入侵成功的因素，例如寄生性，有助于控制和保护当地的本地（濒危）双壳类动物。