Stability of macroinvertebrate communities in vernal ponds following natural drying and refilling events

Abstract Vernal ponds are vital components of forest ecosystems in the eastern United States, providing biodiversity support, water filtration, and flood regulation. Climate change may exacerbate hydrological fluctuations, altering the communities these seasonal wetlands support. This study examines the effects of drying disturbances on macroinvertebrate communities in vernal ponds, focusing on comparing biodiversity metrics before and after hydrological drawdown. We conducted weekly monitoring of pond inundation and macroinvertebrate sampling in five vernal ponds in Central Pennsylvania during 2023. We measured alpha diversity using species richness and Shannon diversity, and calculated temporal beta diversity with Jaccard’s dissimilarity index, examining turnover and nestedness. We found no significant changes in alpha diversity metrics between pre- and post-drying periods. However, we observed a trend toward greater species loss (77% of dissimilarity) compared to gains (23%). Beta diversity patterns of turnover and nestedness were stable across temporal and spatial scales, suggesting that drying disturbances did not significantly affect community structure. These findings contrast with previous studies reporting significant shifts in community composition, potentially due to the adaptive strategies of macroinvertebrates. This research highlights the need for long-term studies to assess drying intensity and informs conservation strategies for vernal pond ecosystems in the context of climate change.