Data from: Characterization of the synoptic-scale diversity, biogeography and size distribution of diatoms in the North Pacific

The diversity, biogeography, and size distribution of diatoms in the North Pacific and underlying mechanisms shaping those patterns have little been characterized despite their importance in marine ecosystems. Here, we examined the community structure of diatoms in the surface and subsurface chlorophyll a maximum (SCM) layers of the North Pacific using light and scanning electron microscopy. Diatom carbon biomass in both the subarctic and temperate coastal regions was higher than that in the open subtropical and tropical waters. Species density was high in the temperate coastal region and certain open ocean stations where coastal water could be intruded. Diversity was generally higher in the SCM layer than that in the surface layer without a clear latitudinal trend. All diatom species in the open subtropical waters were observed in the temperate coastal waters, suggesting that the coastal regions act as a species bank. Certain indigenous species in the subarctic waters were considered as cryophilic species. We found that the general patterns of the size spectrum were nearly identical among different geographical regions of the North Pacific, irrespective of the species composition, environmental conditions, and seasonality. Our results provide mechanistic insights indicating that the diatom biodiversity in the species bank around the coastal region and the following current systems from the coastal to oceanic regions could principally determine biodiversity patterns in the North Pacific. The species-specific ecophysiological traits of diatoms and environmental conditions may further modify the biodiversity patterns and size distribution of diatoms.

尽管硅藻在海洋生态系统中发挥着关键作用，但北太平洋海域硅藻的多样性、生物地理学特征与粒径分布，以及塑造这些分布格局的潜在调控机制，目前仍鲜有系统性研究。本研究依托光学显微镜与扫描电子显微镜，对北太平洋表层及次表层叶绿素a最大值（subsurface chlorophyll a maximum, SCM）层中的硅藻群落结构展开了解析。亚北极与温带近岸海域的硅藻碳生物量，均高于亚热带开阔海域与热带海域。温带近岸海域及部分可受近岸水团侵入的远洋观测站位，物种密度较高。整体而言，SCM层中的硅藻多样性高于表层，但未呈现显著的纬度分布趋势。亚热带开阔海域检出的所有硅藻物种，均在温带近岸海域被观测到，这表明近岸海域可作为物种库（species bank）。亚北极海域的部分土著物种被认定为嗜冷物种（cryophilic species）。本研究发现，无论物种组成、环境条件与季节变化如何，北太平洋不同地理区域的硅藻粒径谱整体格局均高度相似。本研究结果揭示了潜在调控机制：北太平洋近岸海域及其沿岸至远洋的洋流系统所构成的物种库内的硅藻生物多样性，可在本质上决定北太平洋的硅藻生物多样性分布格局。而硅藻的物种特异性生理生态特征与环境条件，可进一步调控硅藻的生物多样性分布格局与粒径分布特征。