Limnoperna fortunei, an invasive mussel altering the structure of benthic communities, is preyed upon by several fish species in South America. To investigate the impact of predatory fish on populations of this mussel, and the effects of this top-down interaction on native macroinvertebrates, we performed an in situ experiment in the Uruguay River. By comparing benthic communities of artificial substrates colonised in treatments allowing or excluding fish access, it was demonstrated that fish significantly reduce colonisation by L. fortunei (i.e. its density, biomass and body size). In the absence of mussels (before settlement), fish preyed upon the native macroinvertebrate community inhabiting artificial substrates, reducing their densities compared to the fish exclusion treatment. However, it was found that in the presence of golden mussel (after settlement), the total density of benthic macroinvertebrates, densities of scrapers, and densities of dipterans and gastropods strongly decreased in fish exclusion treatments, suggesting a strong effect of L. fortunei in reducing the native fauna. By preying on L. fortunei, fish favoured the persistence of native macroinvertebrates. Further studies focused on predatory fish species and their efficiency in removing L. fortunei may contribute to advancing towards using native fish as mitigating agents.

中文翻译：

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鱼类与外星人：掠食性鱼类调节 Limnoperna 财富减轻对本地大型无脊椎动物群落的影响

Limnoperna Fortunei 是一种改变底栖群落结构的入侵贻贝，在南美洲被几种鱼类捕食。为了研究掠食性鱼类对这种贻贝种群的影响，以及这种自上而下的相互作用对本地大型无脊椎动物的影响，我们在乌拉圭河进行了原位实验。通过比较在允许或禁止鱼类进入的处理中定植的人工基质的底栖群落，证明鱼类显着减少了 L. Fortunei 的定植（即其密度、生物量和体型）。在没有贻贝（定居前）的情况下，鱼类捕食栖息在人工基质中的本地大型无脊椎动物群落，与鱼类排除处理相比，它们的密度降低。然而，发现在金贻贝的存在下（沉降后），在鱼类排除处理中，底栖大型无脊椎动物的总密度、刮刀的密度以及双翅目和腹足类的密度显着降低，表明 L. Fortunei 在减少本地动物群。通过捕食 L. Fortunei，鱼类有利于本地大型无脊椎动物的生存。进一步的研究侧重于掠食性鱼类及其去除 L. Fortunei 的效率，可能有助于推进使用本地鱼类作为缓解剂。鱼类有利于本地大型无脊椎动物的持久性。进一步的研究侧重于掠食性鱼类及其去除 L. Fortunei 的效率，可能有助于推进使用本地鱼类作为缓解剂。鱼类有利于本地大型无脊椎动物的持久性。进一步的研究侧重于掠食性鱼类及其去除 L. Fortunei 的效率，可能有助于推进使用本地鱼类作为缓解剂。