Oral Presentation Society for Freshwater Science 2025 Annual Meeting

Ecological stability of zooplankton communities in changing arctic lakes (117046)

Casey A Pennock 1 , Gary P Theide 2 , Phaedra Budy 2 3 4 , Anne Giblin 5 , Chris Leucke 2 4 , George W Kling 6
  1. Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus
  2. Department of Watershed Sciences, Utah State University, Logan
  3. U.S. Geological Survey, Utah Cooperative Fish and Wildlife Research Unit, Logan
  4. The Ecology Center, Utah State University, Logan
  5. The Ecosystems Center Marine Biological Laboratory, Woods Hole
  6. Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor

Understanding ecological stability, the ability of communities or ecosystems to maintain function and structure over time, is a major goal of ecology. Global climate change is altering disturbance regimes with the highest rates of warming occurring at northern latitudes. The Arctic has thousands of relatively pristine lakes that are experiencing both changing press disturbances and increased frequency and intensity of pulse disturbances. We analyzed long-term (14-39 years) data on zooplankton communities and environmental variables from 25 lakes in arctic Alaska. We characterized long-term change and tested the resistance and resilience of communities to natural or experimental press or pulse disturbances. We hypothesized that reference lakes would demonstrate gradual, nondirectional change over time. We also hypothesized that manipulated or disturbed lakes would show directional change with return to pre-disturbance conditions after the disturbance ceased (i.e., resilience). When subject to disturbance, arctic lake ecosystems displayed a mix of ecological stability and resistance, but little resilience. More lakes (15) were changing directionally in terms of environmental variables than in terms of zooplankton communities (10), and nearly twice as many manipulated lakes were changing directionally than were reference lakes for environmental variables. No lakes showed evidence of resilience, despite long recovery times in some manipulated lakes (2-28 years). Zooplankton communities and environmental variables displayed more interannual variation in shallow (<6 m) lakes than in deep lakes. Zooplankton communities and environmental variables were weakly, but significantly, concordant over time with concordance increasing with lake depth. Community changes were due to shifts in species relative abundance, rather than in species turnover. Overall, our results demonstrate that arctic zooplankton communities have low resilience but are changing in both minimally disturbed and experimentally manipulated or otherwise disturbed lakes as climate change continues to alter environmental conditions.