Canopy-forming macroalgae are known to act as ecosystem engineers, altering the physical parameters of the local environment, and as a result, driving changes in local biodiversity. Although a large body of evidence exists regarding macroalgal canopies on intertidal rocky shores, little is known regarding attached perennial species in soft sediment environments. The aim of this study was to assess whether the presence of an Ascophyllum nodosum canopy altered physical parameters, leading to the formation of different environmental conditions in the areas around the canopy and whether this led to changes in the local community. Sediment cores were taken in canopy-present and canopy-absent treatments at four sites over four sampling periods covering winter (November and January) through to spring (March and May) to assess modification of seven physical parameters: particle size, sand/silt/clay content, chlorophyll a, organic carbon, pore water content and temperature, as well as for macrofaunal diversity. Results revealed significant differences between treatments for all variables with the exception of clay content. Areas below the canopy were dominated by a high abundance of opportunistic species indicating a more disturbed environment, with increased levels of organic enrichment, anoxia and scouring found to be the principal sources of physical disturbance. In conclusion, differences in abiotic parameters between canopy and non-canopy areas in soft-sediment environments were driven both directly and indirectly by the presence of the algal canopy. This facilitated an alternative community composition that enhanced biodiversity within algal-sediment shores.

众所周知，形成树冠的大型藻类充当生态系统工程师，改变当地环境的物理参数，从而推动当地生物多样性的变化。尽管存在大量关于潮间带岩石海岸上的大型藻冠的证据，但对于软沉积物环境中附着的多年生物种却知之甚少。本研究的目的是评估泡叶藻冠层的存在是否改变了物理参数，导致冠层周围区域形成不同的环境条件，以及这是否导致当地社区的变化。在从冬季（11 月和 1 月）到春季（3 月和 5 月）的四个采样期内，在四个地点的有冠层和无冠层处理中采集了沉积物岩心，以评估七个物理参数的变化：颗粒大小、沙子/淤泥/粘土含量、叶绿素a 、有机碳、孔隙水含量和温度，以及大型动物多样性。结果显示，除粘土含量外，所有变量的处理之间存在显着差异。树冠以下的区域以大量机会性物种为主，表明环境受到更多干扰，有机富集水平增加、缺氧和冲刷被发现是物理干扰的主要来源。总之，软沉积物环境中冠层和非冠层区域之间非生物参数的差异是由藻冠层的存在直接和间接驱动的。这促进了替代的群落组成，增强了藻类沉积物海岸内的生物多样性。