Macrobenthic metacommunity stability increases with species asynchrony not species richness

Climate change and other anthropogenic pressures are impacting biodiversity and altering the structure, function, and stability of ecosystems worldwide. Understanding the drivers of coastal ecosystem stability amid environmental change remains a global challenge. Here, we investigated temporal (30 years) and spatial (region, estuary, and site) stability dynamics of estuarine macrobenthic communities to elucidate how community stability is affected by environmental variables and biodiversity metrics. Our study provides insights into the mechanisms underpinning community stability in estuarine ecosystems, showing that asynchronous fluctuations in species abundances, arising from spatial heterogeneity among sites and temporal variability, reduce species synchrony and thereby increase stability in heterogeneous estuarine tidal flat systems. Across estuaries and spatial scales, species synchrony consistently exhibited the strongest association with community stability, while effects of species richness on macrobenthic community stability were not detected. Overall, the inverse correlation between species synchrony and community stability across space and time suggested that compensatory dynamics are crucial to maintaining estuarine ecosystem functions and services.