Biomes are geographical units that can be defined based on biological communities sharing specific environmental and climatic requirements. Contemporary ocean biomes have been constructed based on various approaches. These included the biogeographic patterns of higher trophic level organisms, physical and biogeochemical properties, or bulk biological properties such as chlorophyll-a, but none considered the biogeographic patterns of the first trophic level explicitly, i.e. phytoplankton biogeography. A global description of marine biomes based on phytoplankton and defined in analogy to terrestrial vegetation biomes is still lacking. A bioregionalization based on phytoplankton appears particularly timely, as phytoplankton have a high sensitivity to climatic changes and fuel marine productivity. Here, we partition the global ocean into biomes by using self-organizing maps and hierarchical clustering, drawing on the biogeographic patterns of 536 phytoplankton species predicted from empirical evidence. Our approach reveals eight different biomes at the seasonal scale, and seven at the annual scale. The biomes host characteristic phytoplankton species compositions, and differ in their prevailing environmental conditions. The largest differences in phytoplankton composition are found between a Pacific equatorial biome and other tropical biomes, and between subtropical and high latitude biomes. The Pacific equatorial biome is characterized by species with narrower ecological niches, the tropical and subtropical biomes by cosmopolitan generalists, and the high latitudes by species with a heterogeneous biogeography. The strongest differences between biomes are found along gradients of temperature and macronutrient availability, associated with latitude. We test whether our biomes can be reproduced based on indicator species, or potential co-occurrence networks of species determined from the predicted species distributions that are wide-spread in some but rare in other biomes. We find that our biomes can be reproduced by the 51 species identified, which together form significant species co-occurrences. This suggests that species co-occurrences, rather than individual indicator species drive oceanic biome partitioning at the first trophic level. Our biome partitioning may be especially useful for comparative analyses on the functional implications of phytoplankton organization, and impacts on zoogeographical partitionings. Furthermore, it provides a framework for predicting large-scale changes in phytoplankton community structure due to anthropogenic climate and environmental change.

生物群落是可以基于共享特定环境和气候要求的生物群落来定义的地理单位。当代海洋生物群落已经基于各种方法构建。这些包括较高营养级生物的生物地理模式，物理和生物地球化学特性或大量生物特性（例如叶绿素-a），但没有一个人明确考虑第一个营养级的生物地理模式，即浮游植物生物地理。仍然缺乏对以浮游植物为基础并类似于陆生植被生物群落的海洋生物群落的全球描述。基于浮游植物的生物区划似乎特别及时，因为浮游植物对气候变化和燃料海洋生产力具有高度敏感性。这里，我们利用自组织图和层次聚类，将全球海洋划分为生物群落，并根据经验证据预测了536种浮游植物的生物地理格局。我们的方法在季节性尺度上揭示了八个不同的生物群落，在年度尺度上揭示了七个。该生物群落具有特征性的浮游植物物种组成，并且在其主要环境条件方面存在差异。在太平洋赤道生物群落和其他热带生物群落之间，以及在亚热带和高纬度生物群落之间，浮游植物组成的最大差异被发现。太平洋赤道生物群系的特征是生态位较窄的物种，国际通才的热带和亚热带生物群系，以及具有异质生物地理学的物种具有较高的纬度。生物群落之间的最强差异是沿着温度和大量营养素可利用性（与纬度相关）的梯度发现的。我们测试是否可以根据指示物种或根据潜在物种的共生网络来繁殖我们的生物群落，这些物种是根据某些物种中普遍存在但在其他生物群落中很少见的预测物种分布确定的。我们发现，我们的生物群系可以由所确定的51个物种复制，它们共同构成重要的物种共现。这表明，物种共生，而不是单个指示物种，在第一营养级推动了海洋生物群落的分区。我们的生物群落分区可能对浮游植物组织的功能影响以及对动物地理分区的影响进行比较分析特别有用。此外，