Impacts of invasive species are context dependent and linked to the ecosystem they occur within. To broaden the understanding of the impact of a globally widespread invasive oyster, Crassostrea (Magallana) gigas, intertidal surveys were carried out at 15 different sites in Europe. The impact of C. gigas on macro- (taxa surrounding oyster > 1 cm) and epifaunal (taxa on oyster < 1 cm) benthic communities and α and β-diversity was assessed and compared to those associated with native ecosystem engineers, including the flat oyster Ostrea edulis. Whilst the effect of C. gigas on benthic community structures was dependent on habitat type, epifaunal communities associated with low densities of O. edulis and C. gigas did not differ and changes in benthic assemblage structure owing to the abundance of C. gigas were therefore attributed to the presence of oyster shells. Macrofaunal α-diversity increased with C. gigas cover in muddy habitats, while epifaunal α-diversity decreased at greater oyster densities. Macrofaunal β-diversity was greatest at low densities of C. gigas; however, it did not differ between samples without and increased densities of oysters. In contrast, epifaunal β-diversity decreased with increasing oyster cover. Different environmental contexts enabled more independent predictions of the effect of C. gigas on native communities. These were found to be low and more importantly not differing from O. edulis. This indicates that, at low densities, C. gigas may be functionally equivalent to the declining native oyster in terms of biodiversity facilitation and aid in re-establishing benthic communities on shores where O. edulis has become extinct.

中文翻译：

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入侵牡蛎对潮间带组合结构和生物多样性的有限影响：环境背景和与本地物种功能等效的重要性

入侵物种的影响取决于环境，并与它们所处的生态系统有关。为了加深对全球广泛入侵的牡蛎的影响的了解，巨牡蛎（巨牡蛎）在欧洲的 15 个不同地点进行了潮间带调查。评估了 C. gigas 对宏观（牡蛎周围的分类群 > 1 cm）和表层动物群（牡蛎 < 1 cm 的分类群）底栖群落以及 α 和 β 多样性的影响，并与与本地生态系统工程师相关的影响进行了比较，包括平坦的牡蛎 Ostrea edulis。虽然 C. gigas 对底栖群落结构的影响取决于栖息地类型，但与 O. edulis 和 C. gigas 低密度相关的表层动物群落没有差异，并且由于 C. 因此，gigas 归因于牡蛎壳的存在。大型动物 α 多样性随着泥泞栖息地中 C. gigas 的覆盖而增加，而表皮动物 α 多样性在牡蛎密度较大时下降。大型动物 β 多样性在 C. gigas 的低密度下最大；然而，在没有和增加牡蛎密度的样本之间没有差异。相比之下，表层动物 β 多样性随着牡蛎盖度的增加而降低。不同的环境背景能够更独立地预测 C. gigas 对本地社区的影响。这些被发现是低的，更重要的是与 O. edulis 没有区别。这表明，在低密度下，C. gigas 在促进生物多样性和帮助重建 O. 的海岸上的底栖群落方面可能在功能上等同于下降的本地牡蛎。