Distinguishing regions based on the geographic distribution of both abiotic factors and living organisms is an old but still actual central issue for biogeographers. In the Southern Ocean, the few existing regionalization studies have been carried out either at very large scales or on the relatively small region around the Sub-Antarctic islands of Kerguelen and the Crozet archipelagos. However, regionalization studies at meso-scales (100–300 km) covering the Indian part of the Southern Ocean and adjacent South Indian Ocean are scarce. These waters, ranging from the Subtropical to the polar region, are home to large populations of well-studied top predators that depend on the biomass of less known mid-trophic level species such as zooplankton. To fill those gaps, our study aims at conducting bioregional analyses of this transition area at the meso-scale based on the distribution of abiotic factors and chlorophyll-a, and to investigate how the abundance of zooplankton varies across the bioregions identified. To that end, we first characterized epipelagic bioregions 30°S in the South Indian Ocean to 65°S in the Southern Ocean and from 40° to 85°E including the islands of Crozet, Kerguelen, Saint-Paul and New Amsterdam. We then determined whether these bioregions correspond to variations in the abundance of zooplankton collected by a Continuous Plankton Recorder. Finally, we analyzed which environmental parameters influence zooplankton abundance. Our analyses evidenced six regions, providing a synthetic overview of a contrasting environment. The spatial variability of zooplankton abundance was explained by most of the environmental variables used in the bioregionalisation and, to a lesser extent, by the bioregions. Copepods are abundant in the colder and physically-energetic regions associated with the Antarctic Circumpolar Current (ACC). Limacina and euphausids are both abundant in regions characterized by a high concentration of chlorophyll-a, although euphausids are also abundant in the subtropical region. This work represents a crucial step forward in the integration of living organism distribution in the regionalization of the Indian part of Southern Ocean and adjacent South Indian Ocean. This can, ultimately contribute to the optimization of marine conservation strategies.

基于非生物因子和活生物体的地理分布来区分区域对于生物地理学家来说是一个古老但仍是实际的中心问题。在南大洋，很少进行现有的区域化研究，无论是在非常大的规模上，还是在南极亚克尔格伦群岛和克罗泽特群岛周围的相对较小的地区。但是，很少有关于中尺度（100-300 km）的区域化研究覆盖南洋的印度部分和邻近的南印度洋。这些水域的范围从亚热带到极地地区，是大量经过充分研究的顶级捕食者的家园，它们依赖于鲜为人知的中营养水平物种（例如浮游动物）的生物量。为了填补这些空白，-一种，并调查浮游动物的丰度在确定的生物区域之间如何变化。为此，我们首先对南印度洋30°S至南海65°S和40°至85°E的上层生物区进行了特征分析，包括克罗泽特岛，克格伦岛，圣保罗岛和新阿姆斯特丹岛。然后，我们确定这些生物区域是否对应于连续浮游生物记录仪收集的浮游动物丰度的变化。最后，我们分析了哪些环境参数影响浮游动物的丰度。我们的分析证明了六个区域，提供了对比环境的综合概述。浮游生物丰度的空间变异性是由生物分区中使用的大多数环境变量解释的，而在较小程度上是由生物区域解释的。在以高叶绿素-a浓度为特征的区域中，Limacina和euphausids都丰富，尽管在亚热带地区也有丰富的euphausids。这项工作代表了在南大洋印度部分和邻近的南印度洋区域化过程中，生物体分布整合迈出的关键一步。这最终可以有助于优化海洋保护策略。