Multidisciplinary surveys conducted on-board RV Dr Fridtjof Nansen in the northwest Africa region during November 2011 and June 2012 allowed exploration for the first time of seasonal variations in diversity and structure of decapod communities inhabiting the changing hydrological scenario of the shelf and upper slope off Mauritania (20–750 m depth). Decapods were gathered with a commercial bottom trawl at 95 stations, 39 of which were visited in both surveys. In addition, 249 oceanographic profiles and 95 sediment samples were collected. Shelf and slope assemblages, respectively characterized by the dominance of benthic (63 species) and swimming decapods (37 species), were segregated at 100–150 m depth, coinciding with the shelf-break and the hydrological frontier separating the surface mixed layer from the deeper water masses. The assemblages showed a certain stability in their structure but significant seasonal differences in their composition. Abundance and biomass, and in particular specific richness, were strongly correlated with depth in the case of swimming decapods, which were clearly dominant during the warm season, especially in the southern zone. The most significant seasonal variations were mainly due to the Penaeidae family and its associated species,  Parapenaeus longirostris (Lucas, 1846). The latitudinal decreasing trend in upwelling permanence and productivity toward the south, responding to the strength and displacement of trade winds along the Mauritanian coast, which are observable at the surface and sea-bottom, were the main reason explaining the seasonal variations observed in the distribution patterns and assemblages structure of Mauritania decapods.

中文翻译：

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在西北非洲上升流的水文情景变化中，十足动物群落的多样性和结构的季节性变化

房车RV Fridtjof Nansen博士进行的多学科调查在2011年11月至2012年6月期间，对西北非洲地区的首次捕捞活动使十足动物群落的多样性和结构出现了季节性变化，这些动物居住在毛里塔尼亚外陆架和上坡（水深20-750 m）不断变化的水文情景中。十足动物用商业底拖网收集了95个站，在两次调查中都对其中的39个进行了访问。此外，还收集了249个海洋剖面和95个沉积物样本。架子和斜坡组合分别以底栖动物（63种）和游泳十足动物（37种）的优势为特征，在100-150 m深度处被隔离，这与架子断裂和水文边界将表层混合层与更深的水团。这些组合物在结构上显示出一定的稳定性，但是在组成上存在明显的季节性差异。游泳十足动物的丰度和生物量，尤其是特定的丰富度与深度密切相关，在温暖的季节，尤其是在南部地区，十足动物明显占优势。最显着的季节变化主要归因于对虾科及其相关物种， Parapenaeus longirostris（卢卡斯，1846年）。响应于毛里塔尼亚海岸沿面和海底观察到的贸易风的强度和位移，向南持续上升和生产力的纬度下降趋势是解释分布中观测到的季节性变化的主要原因十足动物的模式和组合结构。