Functioning of deep-sea nano- and microfauna food webs fostered by sedimentation of organic matter

虽然深海构成了生物圈的大部分，但人们对其底栖微生物食物网的结构和功能知之甚少。这对于底栖生物中最小的真核生物部分，即原生生物（异养纳米鞭毛虫，裸变形虫和小型纤毛虫）尤其如此。这与微生物可能对深海全球碳通量的潜在重要性形成对比。在第一阶段取得的成果中，有以下成果，其中大部分是新的科学成果，并已在国际期刊上发表：1）我们发现深海沉积物中原生生物的多样性极高，这表明需要了解它们的功能; 2）多样性在小和大的空间尺度上是特定的;（3）在深海中，有过结肠动物、浮游动物和扁形鞭毛虫的特殊分布模式：（4）深海生物群落与半深海上部的生物群落有很大的不同，表明它们是孤立的; 5）大颗粒有机物的沉积改变了原生生物群落结构，尽管这是一个相对缓慢的过程。这里提出了一个更新建议，以阐明一个特定方面，即大型有机颗粒（以沉入海底的马尾藻为例）在深海食物网中的作用。我们假设，大型植物下沉作为一个潜在的重要组成部分的生物泵，结构化社区在深海。我们推测，马尾藻聚集体的殖民地的微生物，而仍然在途中到深海。此外，我们假设深海微型和微型底栖生物可以提高营养贫乏的褐藻的食物质量（例如，通过多不饱和脂肪酸富集），这可能为深海后生底栖动物提供合适的食物来源。我们推测，底栖巨型动物和大型动物被吸引到沉积的马尾藻聚集体的存在。为了解决这些研究问题，我们打算使用一个专用的小型微生物系统，随后对沉积的褐藻进行分子分析，以研究定殖;我们打算用第一阶段分离的深海原生生物和相关细菌培养物进行长期实验室实验，并在普通花园实验中将其添加到褐藻中;我们将对现有的高分辨率AUV海底照片进行重新分析，这些照片的特点是在5000米深处发生了强烈的马尾藻下沉事件，以研究微生物定殖的大型植物对底栖大型和巨型动物的潜在吸引力。

Although the deep sea makes up most of the biosphere, little is known about the structure and function of its benthic microbial food webs. This is especially true for the smallest eukaryote fraction of the benthos, the protists (heterotrophic nanoflagellates, naked amoebae, and small ciliates). This contrasts with the potential importance that microorganisms may have on global carbon fluxes in the deep sea. Among the results obtained in the first phase were the following results, most of which are new to science and have been published in international journals: 1) We found an extremely high diversity of protists in deep-sea sediments, indicating the need to understand their function; 2) Diversity is specific at small and large spatial scales; 3) Specific distribution patterns were exemplified for percolocoans, cafeteriaceans, and placidid flagellates; 4) Deep-sea communities differ significantly from upper bathyal regions, indicating their isolation; 5) Sedimentation of large organic particles alters protist community structure, albeit in a relatively slow process. A renewal proposal is made here to shed light on a particular aspect, namely the role of sinking of large organic particles (exemplified by Sargassum brown algae sunk to the seafloor) on the deep-sea food web. We hypothesize that macrophyte sinking acts as a potentially important part of the biological pump, structuring communities in the deep sea. We hypothesize that Sargassum aggregates are colonized by microorganisms while still en route to the deep sea. Furthermore, we hypothesize that the deep-sea nano- and microbenthos may enhance the food quality of nutrient-poor brown algae (e.g., through PUFA enrichment), which may then provide a suitable food source for the deep-sea metazoobenthos. And we hypothesize that benthic megafauna and macrofauna are attracted to the presence of sedimented Sargassum aggregates. To address these research questions, we intend to use a dedicated small ROV system and subsequent molecular analyses of sedimented brown algae to study colonization; we intend to conduct long-term laboratory experiments with cultures of deep-sea protists and associated bacteria isolated in the first phase and added to the brown algae in common garden experiments; and we will undertake a re-analysis of existing high-resolution AUV seafloor photos of regions characterized by strong Sargassum sinking events at 5000 m depth to study the potential attraction of microbial-colonized macrophytes to benthic large macro- and megafauna.