ENVIRONMENTAL DISEQUILIBRIUM IN CANADIAN FRESHWATER BIOINDICATOR COMMUNITIES

Freshwater monitoring programs worldwide rely on tracking shifts in the abundances of macroinvertebrate bioindicator species, whose populations are thought to reflect freshwater ecosystem health. However, extensive evidence has demonstrated that ecological communities frequently exhibit environmental disequilibrium, where lagged responses to environmental change result in communities composed of species that are mismatched to the observed environment. Here, we use the Canadian Aquatic Biomonitoring Network (CABIN) data, which provides long-term hydrological, chemical, nutrient, and macroinvertebrate measurements, to investigate freshwater macroinvertebrate communities across 100 Canadian watersheds for environmental disequilibrium. Our preliminary results reveal spatial patterns: bioindicator communities in eastern Canadian watersheds are exhibiting environmental disequilibrium, whereas northern and western communities appear closer to environmental equilibrium. Further, using Latent Variable Models, we find that environmental disequilibrium significantly alters the relationships between macroinvertebrate bioindicator taxa and local water chemistry, challenging the reliability of bioindicator-based environmental assessments. Our findings highlight the need for adaptive strategies that incorporate community-environment mismatches, providing insights for more reliable ecosystem monitoring under ongoing environmental change.

Presentation Preference: Standard Oral (12 Minutes)

Primary Presenter: Cindy Gao, McGill University (cindy.gao@mail.mcgill.ca)

Authors:

Cindy Gao, McGill University  (cindy.gao@mail.mcgill.ca)

Zofia Taranu, Environment and Climate Change Canada  (zofia.taranu@ec.gc.ca)

Lars Iversen, McGill University  (lars.iversen@mcgill.ca)