Negligible native and significant alien colonization of artificial shoreline by macroinvertebrates in a large shallow lake (Lake Balaton, Hungary)

The aim of our study was to compare the richness and composition of macroinvertebrate assemblages in natural reed and artificial rip-rap habitats in a shallow lake 50+ years after shoreline modifications. Lake Balaton (Hungary) provided a unique study system as approximately half of its shoreline (c.105 km) has been modified. Littoral macroinvertebrates were collected in two habitat types (artificial rip-rap and natural reed) around the shoreline over two seasons. We found that native taxon richness of rip-rap habitat was only one-twentieth of the natural reed habitat. Rip-rap habitat harboured significantly more alien species. We found that the proportion of alien taxa was higher in rip-rap habitat (89.2%) than in reed habitat (16.7%). The composition of macroinvertebrate assemblages in the two habitats was also significantly different with limited to moderate overlap. Furthermore, all 8 indicator taxa of rip-rap habitat were alien, whilst all 28 indicator taxa were native in reed habitat. These results suggest that artificial engineering structure creates a novel ecosystem dominated by alien species.