Diversity and community structure of kinorhynchs around Svalbard: First insights into spatial patterns and environmental drivers

Abstract

Kinorhyncha is usually one of the more neglected groups in meiofauna ecology. Although their presence is frequently reported in a number of ecological meiofaunal studies, knowledge on their taxonomic composition and distribution at the local and regional scale is very limited. Particularly for the Arctic region, no comprehensive ecological description of kinorhynch communities has yet existed. To address this gap in our knowledge, we compared kinorhynch community structure in different localities: in the region north of Svalbard, in the Barents Sea and four Spitsbergen fjords. Sample locations covered a wide depth gradient from 300 up to 2200 m and different environmental regimes. We analyzed over 4000 individuals among which 18 species belonging to 4 genera and 2 families were identified. The most common species were Echinoderes drogoni and Echinoderes angustus, while the most dominant species was Echinoderes eximus. Patterns of species abundance and shift in their occurrence across the stations were pronounced, with notable distinctions between regions. Three distinct kinorhynch assemblages were observed: ‘fjord assemblage’ dominated by E. eximus and characterized by the highest standing stock and diversity; ‘open water assemblage’ with Echinoderes arlis as dominant species and ‘north of Svalbard assemblage’ characterized by the presence of E. drogoni and Echinoderes peterseni, but at the same time, by the lowest abundance and diversity. We found sediment particle size diversity as the most important explanatory variable. Variation in kinorhynch community structures and diversity was also explained by water depth, but this factor was less important in comparison to sediment characteristics. Surprisingly, food-related variables did not contribute significantly to the model, which could suggest that food partitioning did not influence on promoting diversity. However, it is the first study of arctic kinorhynch ecology and further research is needed to get a more comprehensive understanding of the environmental drivers for turnover in Arctic kinorhynch diversity and distribution.