Waterbody heterogeneity structures appearance history of non-native aquatic species in a freshwater catchment

Freshwater ecosystems have long been exposed to multiple human-mediated stressors, including the introduction and spread of non-native species. Although invasion biology has produced numerous freshwater case studies, the role of waterbody heterogeneity in shaping the invasion history of freshwater catchments has rarely been assessed. To address this knowledge gap, we reconstructed the appearance history of non-native aquatic species in the catchment of the largest shallow lake in Central Europe. The catchment comprises a diverse mosaic of waterbodies, including a large shallow lake (Lake Balaton), a thermal lake (Lake Hévíz), fishponds, and several small watercourses. We found that the arrival of new species was strongly associated with waterbodies differing in environmental characteristics, intensity of human pressures, and pressure histories. Lake Balaton acted as the primary entry point for species introduced via shipping activity. In contrast, Lake Hévíz disproportionately contributed to the appearance of non-native species of Afrotropical origin, consistent with aquarium-mediated introductions. Fishponds represented the major source habitat for species introduced through unintentional releases linked to fish production. Overall, our results demonstrate that heterogeneity of waterbodies plays a substantial role in structuring invasion history in freshwater catchments and should be explicitly incorporated into invasion assessment and management.