Climate change facilitated range expansion of the non-native angular crab Goneplax rhomboides into the North Sea

The angular crab Goneplax rhomboides is native to the north-eastern Atlantic and Mediterranean Sea. It has rarely been reported from the North Sea, with no evidence of sustain- able populations. Compiled survey data, however, revealed an increasing abundance of this spe- cies in the North Sea since 2000. The data were used to (1) describe the range expansion of the angular crab into the North Sea; and (2) to apply species distribution modeling (maximum entropy approach-MAXENT) to predict the potential habitats of this species. Habitats of species with a similar ecology were modeled to analyse habitat overlap and potential competition. The spatial and temporal patterns of records revealed that the expansion of the angular crab into the North Sea is due to natural larval dispersal rather than anthropogenic vectors. Modeled habitats of the angular crab showed a core distribution area along the Scottish coastline and in the southern North Sea. Sea bottom temperatures in February had the highest influence on the model results. We concluded that the angular crab has extended its distribution range from the north-eastern Atlantic to the North Sea, which was facilitated by an increase in water temperature and the pre- vailing hydrodynamics over the last decade. This was the first time that a benthic range expansion was observed in quasi real time for the North Sea. Habitats of the angular crab overlapped those of possible competitors to a large extent. However, co-existence of the species is expected rather than any negative effects resulting from the range expansion of the angular crab.