Declining diversity and abundance of High Arctic fly assemblages over two decades of rapid climate warming

Abstract

Insects are particularly vulnerable to rapid environmental changes, which are disproportionally affecting high latitudes. Increased temperature could influence insect species differentially and reshape assemblages over time. We quantified temporal assemblage turnover of Arctic Diptera (flies) in the Muscidae, one of the most diverse and abundant families of Arctic insects, using time series data from Zackenberg, north‐east Greenland. We measured temporal patterns of abundance, diversity, and composition of muscid assemblages in wet fen, mesic and arid heath habitats from yearly collections spanning 1996–2014 and tested their relationship to climate. A total of 18 385 individuals representing 16 species of muscid flies were identified. A significant decrease of 80% of total muscid abundance was observed during the study period. Species richness declined in each habitat type but this trend was not significant across habitats. The number of common and abundant species also decreased significantly over time across habitats revealing a temporal modification of species evenness. Significant temporal changes in composition observed in the wet fen and across habitats were mainly driven by a change in relative abundance of certain species rather than by species replacement. Shift in composition in each habitat and decline in muscid abundance across habitats were associated with summer temperature, which has significantly increased over the study period. However, relationships between temperature and muscid abundance at the species level were noticeable for a few species only. Significant directional change in composition was documented in the wet fen but no biotic homogenization across habitats was observed. As one of the few studies of species‐level changes in abundance, diversity and composition of an insect taxon in the Arctic over the past two decades, our study shows that habitat types may modulate insect species responses to recent climate change and that contrasting species responses can alter species assemblages within a few decades.

Spatiotemporal snowmelt patterns within a high Arctic landscape, with implications for flora and fauna

“…A strong imprint of snowmelt date was also observed in the phenological timing of many dipteran pollinator groups, in line with previous studies (Iler et al 2013). Muscid flies at Zackenberg show a general decline in abundance during the past two decades, but patterns among individual species are highly dissimilar (Loboda et al 2017). Our species-level data (Wirta et al 2016) from the area suggest that individual muscid fly species differ substantially in phenology.…”

Assessing changes in arthropod predator–prey interactions through DNA‐based gut content analysis—variable environment, stable diet

“…At higher elevation and plots with low vegetation mass, however, the community is increasingly dominated by flower visitors such as muscid flies and chironomid midges. Diptera in general, and muscid flies in particular, are increasingly dominant northwards along a latitudinal gradient in the Arctic (Böcher et al., )—and have declined with warming conditions over time (Høye et al., ; Loboda et al., ). These parallel observations support the interpretation that spatial clines in prey availability seen along our local environmental gradient at Zackenberg may be similar to temporal changes associated with ongoing climate change.…”

“…In contrast to other areas of high‐arctic tundra, vegetation structure at our study area of Zackenberg has been relatively stable so far (IPCC, ; Schmidt, Kristensen, Michelsen, & Bay, ). Yet, the area has experienced changes in flower phenology, soil moisture and air temperature in the last 19 years, leading to a decline in muscid flies and Collembola but to an increase in Hemiptera and parasitoid wasps (Høye et al., ; Koltz et al., ; Loboda et al., ). The availability of the most important prey of Pardosa —chironomid and culicid midges—may perhaps be less affected by climate change due to the buffered, aquatic habitat of their larvae.…”

Tundra arthropods provide key insights into ecological responses to environmental change

“…Tundra arthropods exhibit significant phenological responses to these changes (Høye and Forchhammer 2008;Tulp and Schekkerman 2008;Høye et al 2014). Their body sizes (Høye et al 2009;Bowden et al 2015) and abundances (Koltz et al 2018b;Loboda et al 2018) reflect short-and long-term changes in their abiotic and biotic environments. However, working in remote Arctic, Antarctic, and alpine locations has drawbacks.…”