The Araneae of Svalbard: the relationships between specific environmental factors and spider assemblages in the High Arctic

As top predators in the Arctic invertebrate fauna, spiders in Svalbard are key components of the terrestrial ecosystem. However, most descriptions consist of observations of species occurrence and few repeated sampling campaigns investigating these heterogeneous assemblages, or the relationship between microhabitats and seasonality, exist. Spider assemblages were evaluated along four altitudinal transects (c. 10-300 m above mean sea level) on the west coast of Spitsbergen, Svalbard, throughout the summer of 2012. The slopes were selected to include most of the vegetation types typical for this region of Svalbard. Eleven of the known 15 native spider species were collected (10 Linyphiidae and 1 Gnaphosidae). We used Generalised Linear Models (GLM) for each spider species to identify the factors best explaining spider species abundance and distribution. The distribution of the majority of spider species was best described by vegetation or topography and none was accurately predicted by temperature. Only two species (Erigone arctica palaearctica and Hilaira glacialis) were common at all four sites and these two constituted 54% (1650 and 639 individuals, respectively) of the total spider individuals trapped. That assemblages of linyphiid spiders can differ greatly over small local and temporal scales further demonstrates the complexity of the Arctic terrestrial invertebrate community.