Nonlinear trends in abundance and diversity and complex responses to climate change in Arctic arthropods

Abstract

Time series data on arthropod populations are critical for understanding the magnitude, direction, and drivers of change. However, most arthropod monitoring programs are short-lived and restricted in taxonomic resolution. Monitoring data from the Arctic are especially underrepresented, yet critical to uncovering and understanding some of the earliest biological responses to rapid environmental change. Clear imprints of climate on the behavior and life history of some Arctic arthropods have been demonstrated, but a synthesis of population-level abundance changes across taxa is lacking. We utilized 24 y of abundance data from Zackenberg in High-Arctic Greenland to assess trends in abundance and diversity and identify potential climatic drivers of abundance changes. Unlike findings from temperate systems, we found a nonlinear pattern, with total arthropod abundance gradually declining during 1996 to 2014, followed by a sharp increase. Family-level diversity showed the opposite pattern, suggesting increasing dominance of a small number of taxa. Total abundance masked more complicated trajectories of family-level abundance, which also frequently varied among habitats. Contrary to expectation in this extreme polar environment, winter and fall conditions and positive density-dependent feedbacks were more common determinants of arthropod dynamics than summer temperature. Together, these data highlight the complexity of characterizing climate change responses even in relatively simple Arctic food webs. Our results underscore the need for data reporting beyond overall trends in biomass or abundance and for including basic research on life history and ecology to achieve a more nuanced understanding of the sensitivity of Arctic and other arthropods to global changes.

Recent trends in stream macroinvertebrates: warm-adapted and pesticide-tolerant taxa increase in richness

“…In recent years, many studies have reported declines in insect richness [1][2][3][4][5][6][7]. Nevertheless, it is difficult to generalize trends since regional, taxa-and ecosystem-specific patterns exist [8][9][10][11][12][13]. Although terrestrial insects appear to be declining in many areas, aquatic insects have more frequently been reported to be increasing [14].…”

Synergistic effects of insect herbivory and changing climate on plant volatile emissions in the subarctic tundra

“…While climate change has resulted in decreased abundance and diversity for many species (IPCC, 2014 ; Wagner et al, 2021 ), some insect species have increased their population sizes or range due to warmer temperatures. Thus, the damage by insect herbivores is growing, especially at higher elevations and latitudes (Høye et al, 2021 ; Jepsen et al, 2008 , 2011 ). For example, Barrio et al, ( 2017 ) found that 1.4% of leaf area of the circumpolar dwarf birch ( Betula glandulosa ‐ nana complex) is currently lost due to background insect herbivory, and that with a 1°C increase in summer temperatures, insect herbivory will likely increase by 6–7%.…”

Mismatch‐induced growth reductions in a clade of Arctic‐breeding shorebirds are rarely mitigated by increasing temperatures

“…Phenological advancements in arthropod emergence have nevertheless been shown in some time series (Høye et al, 2007; Rakhimberdiev et al, 2018, but see Meltofte et al, 2021) and predicted from climatic dependencies (Shaftel et al, 2021; Tulp & Schekkerman, 2008). How such advancements impact food available for shorebird chicks will also depend on climate‐induced changes in arthropod community composition (Høye et al, 2021; Koltz et al, 2018), body size (Tseng et al, 2018) activity (Høye & Forchhammer, 2008), and variation in abundance outside of the peak (Machín et al, 2018; Saalfeld et al, 2019). Therefore, whether the occurrence of trophic mismatches is increasing for Arctic‐nesting shorebirds is currently unclear.…”