Pelagic Sargassum macroalgal rafts in the North Atlantic support sessile and motile epifauna that attract ecologically and economically important migratory organisms. Three prevalent pelagic Sargassum morphotypes vary in their degree of branching and foliation, and thus have different structural complexities that can influence their respective value as motile epifauna habitat. Sargassum fluitans III and S. natans I have denser foliation, creating a complex habitat; in contrast, S. natans VIII is more open and architecturally simple. In 2015/2016, 373 dip net samples of algae were collected from the Tropical Atlantic, Greater Caribbean, Gulf of Mexico, Gulf Stream, and Sargasso Sea. 20,975 individual motile epifauna from 32 taxa were recorded. Sargassum fluitans III supported higher densities of individuals and greater numbers of taxa than S. natans VIII or S. natans I, a pattern attributed to its more complex architecture and consistent with communities on benthic and floating macroalgae. Most assemblages comprised a few dominant and many rare motile epifauna; when compared to historical studies, dominant motile epifauna had shifted. These findings suggest important differences in ecological value between pelagic Sargassum morphotypes with implications for coastal and pelagic conservation strategies, which warrant consideration given recent shifts in morphotype distribution and recurring pelagic Sargassum inundation events.

北大西洋中的远洋马尾藻大型藻筏支持无柄和能动的表层动物群，吸引在生态和经济上具有重要意义的迁徙生物。三种流行的远洋马尾藻形态类型的分枝和叶状程度各不相同，因此具有不同的结构复杂性，可以影响它们作为活动表层动物栖息地的各自价值。Sargassum fluitans III和S. natans I有更密集的叶子，创造了一个复杂的栖息地；相比之下，S. natans VIII更开放，架构更简单。2015/2016 年，从热带大西洋、大加勒比海、墨西哥湾、墨西哥湾流和马尾藻海收集了 373 个藻类浸网样本。记录了来自 32 个分类群的 20,975 个个体活动表皮动物。Sargassum fluitans III比S. natans VIII或S. natans I支持更高的个体密度和更多的分类群，这种模式归因于其更复杂的结构并且与底栖和漂浮的大型藻类群落一致。大多数组合包括少数占优势的和许多稀有的活动表皮动物群；与历史研究相比，占主导地位的活动表层动物群发生了变化。这些发现表明远洋马尾藻之间生态价值的重要差异对沿海和远洋保护战略有影响的形态类型，考虑到最近形态类型分布的变化和反复出现的远洋马尾藻淹没事件，值得考虑。