This study was carried out in the Yenisei estuary and in the adjacent part of the Kara Sea shelf. We analyzed and compared the distribution patterns of the different benthic taxa and size classes (micro-, meio-, macro- and megabenthos) along a pronounced gradient of environmental factors. Four ecological zones were distinguished based on certain environmental parameters, from the upper riverine area to the mouth of the estuary and the Kara Sea slope, which had normal marine conditions. The distribution of the metazoan assemblages generally corresponded to the divisions of these zones and represented a series of species assemblages with coincident boundaries that changed successively along the estuarine gradient. For all three size classes of metazoan benthos, we detected three main species assemblages: brackish-water, transitional and marine. Each taxon showed, however, its own particular spatial pattern and, therefore, has a set of environmental variables that is responsible for its fine-scale distribution. The distribution of unicellular organisms showed a worse match with the division of the estuary into environmental zones. Foraminifers established a single association in most of the estuary but were absent in the upper desalinated part. Diatom algae were patchily distributed, with a number of local communities and many rare species.

We conclude that the estuarine habitat appears to drive the distribution of the various benthic taxa in taxa-specific ways. The distribution of size classes (i.e., mega-, macro-, or meiofauna) that combine several high-level taxa demonstrates a better match with the multivariate environmental zonation than the distribution of the separate taxa. The role of different benthic taxa and size classes in biomonitoring studies is discussed.

这项研究是在叶尼塞河口和卡拉海陆架的相邻部分进行的。我们分析并比较了不同底栖生物分类和大小类别（微型，中型，大型和大型底栖动物）沿环境因子明显梯度的分布模式。根据某些环境参数，从河流上游地区到河口河口和卡拉海坡（具有正常海洋条件）区分了四个生态区。后生动物组合的分布通常对应于这些区域的划分，并代表一系列物种组合，其重合边界沿河口梯度连续变化。对于后生动物底栖动物的所有三个大小类别，我们检测到三个主要物种组合：微咸水，过渡性和海洋性。但是，每个分类单元都显示其自己的特定空间模式，因此具有一组环境变量，这些环境变量负责其精细的分布。单细胞生物的分布与河口划分为环境区的匹配较差。有孔虫在大多数河口建立了一个单一的协会，但在淡化的上部没有。硅藻藻类零星分布，有许多当地社区和许多稀有物种。有孔虫在大多数河口建立了一个单一的协会，但在淡化的上部没有。硅藻藻类零星分布，有许多当地社区和许多稀有物种。有孔虫在大多数河口建立了一个单一的协会，但在淡化的上部没有。硅藻藻类零星分布，有许多当地社区和许多稀有物种。

我们得出的结论是，河口栖息地似乎以特定于生物分类的方式驱动各种底栖生物分类的分布。结合了多个高级分类单元的规模类别（即大型，大型或小型动物）的分布与多元环境分区相比，比单独分类单元的分布具有更好的匹配性。讨论了不同底栖生物分类和大小类别在生物监测研究中的作用。