Impacts of invasive species are often context specific due to varying ecological interactions. Physical structure of environments hosting invaders is also potentially important but has received limited attention. An invasive macroalga, Agarophyton vermiculophyllum, has spread across the northern hemisphere with mixed positive, neutral and negative effects on resident species. Agarophyton colonizes mudflats that vary in topography due to interactions of sediments with hydrodynamic forces. We tested the hypothesis that mudflat geomorphology moderates the effect of Agarophyton on shorebirds and invertebrates. We surveyed 30 mudflats in the Virginia Coast Reserve quantifying elevation and topography. Invertebrate and bird abundances were also quantified. Mudflat geomorphology ranged from smooth to hummocky and was correlated with invertebrate and shorebird abundance and interactions based on piecewise structural equation models. After accounting for geomorphology, Agarophyton had little effect on invertebrate abundance. Shorebird numbers were differentially influenced by mudflat topography, with positive correlations to invertebrates (worms) on smooth mudflats, and to macroalgae on hummocky mudflats. These differences are likely to be due to sediment properties in interaction with structural changes induced by Agarophyton mats that affect prey accessibility for birds. Even on apparently simple mudflats, geomorphic structure emerged as important, modifying invasive species impacts and differentially influencing consumers.

中文翻译：

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泥滩地貌决定了大型藻类对无脊椎动物猎物和水鸟捕食者的影响

由于不同的生态相互作用，入侵物种的影响通常因环境而异。宿主入侵者的环境的物理结构也可能很重要，但受到的关注有限。一种侵入性大型藻类Agarophyton vermiculophyllum已遍布北半球，对常驻物种产生了积极、中性和消极的混合影响。由于沉积物与水动力的相互作用，Agarophyton定居在地形变化的泥滩上。我们检验了泥滩地貌缓和Agarophyton影响的假设对水鸟和无脊椎动物。我们调查了弗吉尼亚海岸保护区的 30 个泥滩，以量化海拔和地形。无脊椎动物和鸟类的丰度也被量化。基于分段结构方程模型，泥滩地貌从光滑到丘状不等，与无脊椎动物和鸻鹬的丰度和相互作用相关。考虑到地貌后，Agarophyton对无脊椎动物的丰度影响不大。滨鸟数量受泥滩地形的不同影响，与光滑泥滩上的无脊椎动物（蠕虫）和丘状泥滩上的大型藻类呈正相关。这些差异可能是由于沉积物特性与Agarophyton引起的结构变化相互作用影响鸟类猎物可及性的垫子。即使在看似简单的泥滩上，地貌结构也很重要，它改变了入侵物种的影响，并对消费者产生了不同的影响。