1. The disproportionately low presence of marine species in the list of invasive alien species (IAS) of Union concern of the European Union (EU) Regulation 1143/2014 does not fully acknowledge the threat they pose to the EU marine environment.
2. In this study, the first EU‐scale Horizon Scanning (HS) focusing on marine alien species was performed, aiming to deliver a ranked list of species that should be of high priority for risk assessment (Article 5 of the EU IAS Regulation).
3. Species absent from or with a limited distribution in EU marine waters were targeted. In total, 363 alien species were initially screened for HS by a panel of experts, including a broad range of taxonomic groups. Species were scored for their likelihood of arrival, establishment, spread, and impact in EU waters.
4. A consensus workshop ranked 267 species, including a subset of 26 prioritized species. These species are considered to be mainly introduced by shipping (fouling and ballast water), via the Suez Canal, and aquaculture activities. The 26 priority species were also scrutinized in terms of feasibility of their management; 18 of them were suggested for performing risk assessments on the basis of the EU IAS Regulation.
5. Since biological invasions are dynamic and connected with accelerated globalization and diversified human activities, we recommend HS to be repeated periodically to review the species already listed and assess new ones.

中文翻译：

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通过地平线扫描优先考虑欧盟的海洋外来入侵物种

1. 欧洲联盟（EU）法规1143/2014所关注的外来入侵物种（IAS）列表中海洋物种的比例过低，并不完全承认它们对欧盟海洋环境构成的威胁。
2. 在这项研究中，首次进行了针对海洋外来物种的欧盟规模的水平扫描（HS），旨在提供风险评估应高度重视的物种排名列表（欧盟IAS法规第5条）。
3. 目标是不存在或分布在欧盟海水中的物种。最初，总共有363种外来物种通过专家小组（包括广泛的分类学组）进行了HS筛查。对物种在欧洲水域的到达，建立，传播和影响的可能性进行了评分。
4. 共识研讨会对267种进行了排名，其中包括26种优先种的子集。这些物种被认为主要是通过苏伊士运河通过航运（污染和压舱水）以及水产养殖活动引入的。还对26种优先物种进行了管理可行性审查；建议根据欧盟IAS法规中的18条进行风险评估。
5. 由于生物入侵是动态的，并且与加速的全球化和人类活动的多样化有关，因此我们建议定期重复HS，以审查已经列出的物种并评估新物种。