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

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  • Toke T. Høye
  • Sarah Loboda, McGill University
  • ,
  • Amanda M. Koltz, Washington University in St Louis
  • ,
  • Mark A. K. Gillespie, Western Norway University of Applied Sciences
  • ,
  • Joseph J. Bowden, Natural Resources Canada
  • ,
  • Niels M. Schmidt
Arthropods are excellent indicators for studying global change in the rapidly changing climate of the Arctic. We used the most comprehensive standardized dataset on Arctic arthropods to quantify diversity and abundance variation over 24 y in an area that is warming rapidly. Overall arthropod abundance and diversity showed opposing nonlinear trends, with a sharp increase in overall abundance in recent years. However, trends varied substantially among taxa and habitats and several groups declined in abundance. We found strong evidence of conditions outside the growing season and density-dependent feedbacks affecting abundance. Our results emphasize the need for a more integrated approach to investigating arthropod responses to environmental stressors at finer taxonomic resolution and by incorporating time-lagged effects.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.Species records and climate data reported in this paper have been retrieved from the Greenland Ecosystem Monitoring Database (https://doi.org/10.17897/V285-Z265).
Original languageEnglish
Article numbere2002557117
JournalProceedings of the National Academy of Sciences of the United States of America
Number of pages8
Publication statusPublished - 2021

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