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

Vernal ponds are essential components of forested ecosystems in the eastern United States, providing crucial ecosystem services such as water filtration, biodiversity support, and flood regulation. Characterized by their seasonal drying, these ponds are increasingly affected by climate change, which may intensify hydrological fluctuations and impact the communities they support. This study investigates the effects of drying disturbances on macroinvertebrate communities in vernal ponds, focusing on biodiversity metrics before and after hydrological drawdown. Weekly monitoring of pond inundation and macroinvertebrate sampling was conducted in five vernal ponds in Central Pennsylvania during 2023. Alpha diversity was assessed using species richness and Shannon diversity, while temporal beta diversity was analyzed with Jaccard’s dissimilarity index, examining turnover and nestedness components. Our findings indicate no significant changes in alpha diversity metrics between pre- and post-drying periods. However, there was a trend toward greater species losses (77% of dissimilarity) compared to gains (23%), though the evidence for this difference was weak. Beta diversity analyses demonstrated stable patterns of turnover and nestedness across temporal and spatial scales, suggesting that drying disturbances did not significantly disrupt macroinvertebrate community structure. These results contrast with previous studies reporting significant shifts in community composition following similar disturbances. This discrepancy may be due to the adaptive strategies of macroinvertebrates or the influence of metacommunity dynamics in species reestablishment. This research underscores the necessity of long-term studies and detailed assessments of drying intensity to better understand climate change impacts on vernal pond ecosystems. The insights gained can inform effective conservation strategies, making these findings relevant to an international audience interested in wetland ecology and biodiversity preservation.