1 INTRODUCTION

Biological invasions continue to alter and, in some cases, detrimentally impact ecosystem function worldwide, resulting in a plethora of environmental, economic and social problems (Haubrock et al., 2021; Simberloff et al., 2013). Rates of biological invasion continue to increase, with intensifying trade and transport networks driving introductions from disparate biogeographical regions (Bailey et al., 2020; Seebens et al., 2017, 2021). Management strategies for invasive alien species are reliant on evidence-based, data-driven science (Dick et al., 2017), yet have hitherto been largely insufficient in reducing ecological and economic damages (Cuthbert, Pattison, et al., 2021a). Specifically, understanding the abiotic and biotic correlates of biological invasions, whose status can be quantified using numerous metrics such as occurrence, extent or proportional cover, requires a holistic approach in considering potential drivers of invasion throughout the total environment. Therefore, the consideration of multiple variables in concert is increasingly required to better understand and predict invasions worldwide.

Aquatic ecosystems are regarded as particularly vulnerable to biological invasions and their impacts (Ricciardi & MacIsaac, 2011). Invasive aquatic macrophytes often are recorded to be ecologically and economically damaging, for example, through increased flood risk, devaluation of property, the disruption of navigation, water abstraction, irrigation and recreational activities (Hussner et al., 2017; Oreska & Aldridge, 2011). Studies typically have focused on a small number of variables to explain invasion success, including the relationships between macrophytes and spatiotemporal patterns in water quality and the surrounding land use (Lougheed et al., 2001; Sass et al., 2010). A more comprehensive understanding of invasion drivers, including the emergent effects of other species impacts and their abiotic interactions, is needed to enhance predictive capacities for future invasions.

Elodea nuttallii (Planch.) St John is a perennial, submerged aquatic macrophyte which is native to North America and invasive in Europe, Asia and Australasia (Barrat-Segretain et al., 2002; Jones et al., 2000; Zehnsdorf et al., 2015). Introduced to Great Britain and Ireland in 1966, E. nuttallii typically inhabits lakes, ponds and slow-moving rivers (Barrat-Segretain et al., 2002; Champion et al., 2010), often displacing Elodea canadensis, a congeneric invasive macrophyte (Simpson, 1990). Notably, E. nuttallii can grow in highly eutrophic, turbid waters (Cook & Urmi-König, 1985; Ozimek et al., 1993; Thiébaut & Muller, 1999), and can rapidly dominate invaded ecosystems through the formation of dense monospecific stands that outcompete native macrophytes and significantly alter freshwater communities (Angelstein & Schubert, 2008; Champion et al., 2010; Thouvenot & Thiébaut 2018; Zehnsdorf et al., 2015). Furthermore, it appears that E. nuttallii can be transported long distances overland by anthropogenic vectors (Coughlan et al., 2018; Kelly et al., 2014).

Interestingly, E. nuttallii often co-occurs with invasive dreissenid bivalves (Crane et al., 2020), such as the zebra mussel Dreissena polymorpha (Pallas 1771), itself a prolific Ponto-Caspian species that frequently dominates invaded ecosystems, causing myriad ecological and socioeconomic impacts (Sousa et al., 2014). Dreissena polymorpha impacts include displacement of native mussels, increased water clarity, altered nutrient cycling, and shifts in filamentous algal blooms and macrophyte assemblage composition (Ricciardi, 2003; Ricciardi et al., 1998; Rosell et al., 1999; Ward & Ricciardi, 2007). Given increasing accumulations of invaders in aquatic ecosystems (Ricciardi, 2015), understanding how multiple invasive alien species interact and respond to variability in environmental conditions is essential to understanding the spatiotemporal dynamics of invasions, which inform the scale of any management actions required. Empirical data indicate that the presence of D. polymorpha can promote facilitative interactions in favour of E. nuttallii (Crane et al., 2020). However, the extent of potential facilitations between invasive alien species in field-based conditions has not been rigorously tested, nor compared with additional environmental variables that might mediate invasion dynamics.

The aim of this study was to identify the environmental correlates of a major E. nuttallii invasion in Lough Erne; a large (c. 144 km²) freshwater lake in Northern Ireland, capturing the invasion status using three metrics: occurrence (presence/absence), extent (area in hectares) and proportional cover (percentage cover). The objective was to assess environmental correlates of E. nuttallii including spatial and temporal trends in water quality variables, as well as surrounding land cover and land use. In addition, we included the co-occurrence of E. nuttallii with D. polymorpha within our analyses with the objective of assessing the potential role played by interspecific interactions in the distribution of E. nuttallii alongside the environmental variation.

中文翻译：

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入侵水生伊洛狄亚的发生、范围和覆盖的非生物和生物相关性

1 简介

生物入侵继续改变，在某些情况下，对全球生态系统功能产生不利影响，导致过多的环境、经济和社会问题（Haubrock 等人，  2021 年；Simberloff 等人，  2013 年）。生物入侵率继续增加，贸易和运输网络的加强推动了来自不同生物地理区域的引入（Bailey 等人，  2020 年；Seebens 等人，  2017 年，2021 年）。外来入侵物种的管理策略依赖于以证据为基础的数据驱动科学（Dick 等人，  2017 年），但迄今为止在减少生态和经济损害方面还远远不够（Cuthbert、Pattison 等人， 2021a )。具体来说，了解生物入侵的非生物和生物相关性（其状态可以使用发生、程度或比例覆盖等众多指标进行量化）需要一种整体方法来考虑整个环境中入侵的潜在驱动因素。因此，越来越需要同时考虑多个变量，以更好地理解和预测世界范围内的入侵。

水生生态系统被认为特别容易受到生物入侵及其影响（Ricciardi & MacIsaac,  2011）。入侵水生植物经常被记录为对生态和经济造成破坏，例如，通过增加洪水风险、财产贬值、破坏航行、取水、灌溉和娱乐活动（Hussner 等人，  2017 年；Oreska & Aldridge，  2011 年） ）。研究通常集中在少数变量来解释入侵成功，包括大型植物与水质和周围土地利用的时空模式之间的关系（Lougheed 等，  2001；Sass 等，  2010）。需要更全面地了解入侵驱动因素，包括其他物种影响的紧急影响及其非生物相互作用，以提高对未来入侵的预测能力。

Elodea nuttallii (Planch.) St John 是一种多年生沉水大型水生植物，原产于北美，侵入欧洲、亚洲和大洋洲（Barrat-Segretain 等人，  2002；Jones 等人，  2000；Zehnsdorf 等人。 ,  2015 年）。E. nuttallii于 1966 年被引入英国和爱尔兰，通常栖息在湖泊、池塘和缓慢流动的河流中（Barrat-Segretain 等人，  2002 年；Champion 等人，  2010 年），经常取代同属入侵性大型植物Elodea canadensis（辛普森，  1990 年）。值得注意的是，E. nuttallii可以在高度富营养化、浑浊的水中生长（Cook & Urmi-König，  1985; Ozimek 等人，  1993 年；Thiébaut & Muller,  1999 )，并且可以通过形成密集的单种林分迅速支配入侵的生态系统，这些林分胜过本地大型植物并显着改变淡水群落 (Angelstein & Schubert,  2008 ; Champion et al.,  2010 ; Thouvenot & Thiébaut 2018 ; Zehnsdorf et等人，  2015 年）。此外，似乎E. nuttallii可以通过人为载体进行长距离陆路运输（Coughlan 等人，  2018 年；Kelly 等人，  2014 年）。

有趣的是，E. nuttallii经常与入侵的 dreissenid 双壳贝类（Crane 等人，  2020 年）同时出现，例如斑马贻贝Dreissena polymorpha (Pallas 1771)，它本身就是一种多产的 Ponto-Caspian 物种，经常在入侵的生态系统中占主导地位，导致无数生态和社会经济影响（Sousa 等人，  2014 年）。Dreissena polymorpha的影响包括原生贻贝的置换、水的清澈度增加、养分循环的改变以及丝状藻华和大型植物组合组成的变化（Ricciardi，  2003；Ricciardi 等，  1998；Rosell 等，  1999；Ward & Ricciardi，  2007年）。鉴于入侵者在水生生态系统中的不断积累（Ricciardi，  2015 年），了解多种外来入侵物种如何相互作用并应对环境条件的变化对于了解入侵的时空动态至关重要，这为所需的任何管理行动的规模提供信息。经验数据表明，D. polymorpha的存在可以促进有利于E. nuttallii的促进相互作用（Crane 等人，  2020 年）。然而，在野外条件下外来入侵物种之间的潜在促进程度尚未经过严格测试，也未与可能介导入侵动态的其他环境变量进行比较。

本研究的目的是确定 Lough Erne 的主要E. nuttallii入侵的环境相关性；北爱尔兰的一个大型（c. 144 km ^{2 ）淡水湖，使用三个指标捕捉入侵状态：发生（存在/不存在）、范围（以公顷为单位的面积）和比例覆盖（覆盖百分比）。}目的是评估E. nuttallii的环境相关性，包括水质变量的空间和时间趋势，以及周围的土地覆盖和土地利用。此外，我们在分析中包括了E. nuttallii与D. polymorpha的共现，目的是评估种间相互作用在分布中所起的潜在作用。E. nuttallii以及环境变化。