Kelps are dominant primary producers in temperate coastal ecosystems. Large amounts of kelp biomass can be exported to the seafloor during the algal growth cycle or following storms, creating new ecological niches for the associated microbiota. Here, we investigated the bacterial community associated with the kelp Laminaria hyperborea during its accumulation and degradation on the seafloor. Kelp tissue, seawater and sediment were sampled during a 6‐month in situ experiment simulating kelp detritus accumulation. Evaluation of the epiphytic bacterial community abundance, structure, taxonomic composition and predicted functional profiles evidenced a biphasic succession. Initially, dominant genera (Hellea, Litorimonas, Granulosicoccus) showed a rapid and drastic decrease in sequence abundance, probably outcompeted by algal polysaccharide‐degraders such as Bacteroidia members which responded within 4 weeks. Acidimicrobiia, especially members of the Sva0996 marine group, colonized the degrading kelp biomass after 11 weeks. These secondary colonizers could act as opportunistic scavenger bacteria assimilating substrates exposed by early degraders. In parallel, kelp accumulation modified bacterial communities in the underlying sediment, notably favouring anaerobic taxa potentially involved in the sulfur and nitrogen cycles. Overall, this study provides insights into the bacterial degradation of algal biomass in situ, an important link in coastal trophic chains.

中文翻译：

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潮下温带沿海生态系统中分离海带生物量的积累诱导附生和沉积物细菌群落的演替


海带是温带沿海生态系统的主要初级生产者。在藻类生长周期或风暴过后，大量海带生物质可以出口到海底，为相关微生物群创造新的生态位。在这里，我们研究了与海带海带在海底积累和降解过程相关的细菌群落。在模拟海带碎屑堆积的为期 6 个月的原位实验中，对海带组织、海水和沉积物进行了采样。对附生细菌群落丰度、结构、分类组成和预测功能谱的评估证明了双相演替。最初，优势属（海藻属、滨单胞菌属、颗粒球菌属）的序列丰度迅速急剧下降，可能在 4 周内做出反应的拟杆菌属等藻类多糖降解菌的竞争中胜出。 11周后，酸性微生物，特别是Sva0996海洋群体的成员，在正在降解的海带生物量中定殖。这些次生定殖者可以充当机会性清道夫细菌，同化早期降解者暴露的底物。与此同时，海藻的积累改变了底层沉积物中的细菌群落，特别有利于可能参与硫和氮循环的厌氧类群。总体而言，这项研究提供了对藻类生物质原位细菌降解的见解，这是沿海营养链的重要环节。