Community Synchrony in Aquatic Macroinvertebrates Is Unrelated to Environmental Variability but Differs Among Functional Feeding Groups.

Environments are becoming increasingly more variable, as a function of climate change. As this occurs, species may be exposed to conditions outside their preferred range. Such variability in the environment can influence community abundance as individual species respond either similarly (synchronous dynamics) or differently (asynchronous dynamics) to each other. These fluctuations in abundances are important for understanding the impact of environmental variability on species temporal fluctuations in aquatic macroinvertebrates. This group of organisms is species-rich and highly sensitive to environmental fluctuations. We analyzed 18 stream macroinvertebrate communities sampled by the National Ecological Observatory Network between 2014 and 2022 to understand how community synchrony is related to stream temperature variability, discharge variability, and species turnover. We then quantified individual species contributions to community synchrony. These contributions were aggregated by functional feeding group to understand how resource acquisition strategies influenced species contributions. Species with higher contributions are often more synchronous with many other species. Here, community synchrony was expected to be negatively related to increasing environmental variability and turnover. Opposite our expectation, temperature variability, turnover, and discharge variability were unrelated to community synchrony. Contributions to community synchrony significantly varied among functional feeding groups. Scrapers had the highest proportion of taxa with significant positive contributions, followed by filterers. Shredders had the lowest proportion of species contributing to synchrony. Scrapers and shredders were significantly less synchronous than other functional feeding groups. This suggests that functional feeding group may explain patterns of community synchrony. Using a standardized, long-term dataset, we demonstrated how temperature variability, turnover, and functional feeding groups relate to community synchrony. While identifying the drivers of community synchrony remains challenging, integrating functional groupings provides an approach to identify species that drive community dynamics.