Hidden under ice and mud: diversity of shell-bearing microgastropods in the eastern Arctic seas

The arctic environment continues to undergo a rapid transformation due to climatic shifts, human activities, and invasive species. Revealing ecosystem responses to these stressors requires extensive knowledge about the diversity of the Arctic fauna and flora. Gastropoda is one of the most diverse invertebrate groups within the marine benthos. Shell-bearing microgastropods (snails no larger than 5 mm) represent a significant part of gastropod diversity but remain among the most poorly studied marine animals worldwide. The aim of the present review is to summarize the existing data on diversity and distribution of shell-bearing microgastropods in the eastern Arctic seas. Currently, 66 species of shell-bearing microgastropods belonging to 17 families are known from the region. The taxonomy of snails is still based mainly on shell characters. Molecular phylogenetic analysis still has not been used in the taxonomy of microgastropods from the eastern Arctic. The Barents Sea is the most species-rich region with 51 microgastropod species. The diversity in the other seas is significantly lower, from 10–20 species, and only 9 species in the case of the open Arctic basin. Analysis of functional traits revealed three groups of microgastropods: coastal species feeding on algae and detritus, shelf species feeding on foraminiferans, and parasitic/symbiotic species. Abundance of shell-bearing microgastropods can be high, especially in coastal environments, where micromolluscs may be the most numerous among all the macroinvertebrates. Some limitations for studies of microgastropods in the Arctic are reviewed.

受气候变化、人类活动与外来物种入侵影响，北极环境正经历快速演变。阐明生态系统对这些胁迫因子的响应，需全面掌握北极动植物区系的多样性信息。腹足纲（Gastropoda）是海洋底栖生物中多样性最高的无脊椎动物类群之一。具壳微型腹足类（个体尺寸不超过5毫米的螺类）是腹足纲多样性的重要组成部分，却是全球范围内研究程度最低的海洋动物类群之一。本综述旨在梳理现有关于北极东部海域具壳微型腹足类的多样性与分布的相关数据。目前该区域已记录到隶属于17个科的66种具壳微型腹足类。当前此类螺类的分类仍主要依据壳体形态特征，北极东部海域微型腹足类的分类研究尚未应用分子系统发育分析手段。巴伦支海是物种丰富度最高的区域，共记录有51种微型腹足类；其他海域的多样性显著偏低，仅记录有10至20种，而北极开阔海盆仅记录到9种。功能性状分析将微型腹足类划分为三大类群：以藻类和碎屑为食的近岸类群、以有孔虫（foraminiferans）为食的陆架类群，以及寄生/共生类群。具壳微型腹足类的丰度可达到较高水平，尤其在近岸生境中，微型软体动物可能是所有大型无脊椎动物中数量最多的类群。本综述同时梳理了北极微型腹足类研究面临的若干局限。