The assemblage structure and spatial distribution patterns of macrobenthic communities according to environmental conditions were analysed through five samplings carried out at 14 intertidal soft sediment stations in the Oualidia lagoon (NW Morocco). A total of 89 macrobenthic taxa were collected, amounting to 55.188 specimens. Molluscs, polychaetes and arthropods were the most species‐rich groups. The snail Peringia ulvae was the most dominant species, especially abundant in the mid‐ and upper lagoon sections (nearly 64% of the total specimens gathered), followed by the mollusc Scrobicularia plana (10%). Diversity values were generally low (<3 bit) pointing out the high dominance by few species. Multivariate analyses clearly distinguished three distinct macrobenthic assemblages, successively distributed from lagoon inlets towards inner parts. Nevertheless, each assemblage was found in particular habitat types and had a specific species composition in response to different environmental characteristics. (a) The Scolelepis fuliginosa community occupied sandy substrates at the lower section of the lagoon with stronger marine influence and, (b) the P. ulvae community lived in sandy‐muddy substrates, including two sub‐communities dominated, respectively, by Cerastoderma edule, S. plana and Tritia pfeffeiri inhabiting the middle section and S. plana the upper section. The combination of salinity, temperature, pH and silt content was identified as the major environmental variable subset with the highest correlation with the observed macrofaunal patterns and silt fraction as the single best correlated variable. The results demonstrated significant spatial differences in macrobenthic assemblage structure and composition along environmental gradients in spite of the absence of direct freshwater river inflow.

中文翻译：

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没有河流排放的泻湖中大型动物的空间分布和群落结构（摩洛哥西北部的瓦利迪亚泻湖）

通过在Oualidia泻湖（西北摩洛哥）的14个潮间带软沉积物站进行的五次采样分析了根据环境条件的大型底栖动物群落的组成结构和空间分布模式。总共收集了89个大型底栖生物类群，共计55.188个标本。软体动物，多毛类和节肢动物是物种最多的群体。蜗牛的Peringia ulvae是最主要的物种，在泻湖中部和上部的泻湖中尤为丰富（占采集标本的近64％），其次是软体类Scrobicularia plana（10％）。多样性值通常较低（<3位），表明少数物种具有较高的优势。多变量分析清楚地区分了三个不同的大型底栖动物组合，它们从泻湖入口向内部依次分布。但是，每种组合都在特定的栖息地类型中发现，并且根据不同的环境特征具有特定的物种组成。（a）Scolelepis fuliginosa群落占据了泻湖下部的沙质底物，对海洋产生了较大的影响；（b）ul。P. ulvae群落生活在沙泥底质中，包括两个分别以角皮病为主的亚社区，S。Plana和Tritia pfeffeiri居住在中间部分和平坦的葡萄球菌的上部。盐度，温度，pH和淤泥含量的组合被确定为主要的环境变量子集，与观察到的大型动物群落模式具有最高的相关性，淤泥分数是唯一的最佳相关变量。结果表明，尽管没有直接的淡水河流入，大型底栖动物的组合结构和组成沿环境梯度仍存在明显的空间差异。