Time waits for no one: a long-term study of the dynamics of nematode metacommunities in newly formed ponds

Abstract Understanding how ecological communities assemble through time requires integrating temporal dynamics with species’ life-history and functional traits. Here, we investigated long-term dynamics of nematode communities inhabiting the sediment of eight newly created ponds. We measured abundance, species richness, and community composition monthly over 3 years in all ponds and over 10 years in one pond, representing approximately 10–100 generations for most free-living nematode species. Abundances increased, reaching peak densities within 3 years, while local species richness was highest during the first 2 months and declined thereafter. Across ponds, dominant species diverged in relative abundance, indicating parallel colonization followed by idiosyncratic successional trajectories. Early communities were dominated by fast-reproducing, opportunistic species, suggesting trait-based filtering during colonization. Positive temporal covariation among species abundances indicated that dynamics were primarily driven by shared environmental constraints rather than compensatory interactions. Long-term data revealed dramatic community shifts following anoxic events, highlighting how disturbance can reset successional trajectories and favor taxa with contrasting ecological strategies. Our results demonstrate that extended temporal analyses integrating species’ life-history traits are essential for understanding the balance between neutral colonization and niche-based filtering during community assembly. Short-term studies would have missed initial colonization and subsequent community reorganization under realistic disturbance regimes.