Biological invasions are threatening aquatic biodiversity, fisheries resources and coastal economies. However, we still lack the basic information associated with the mechanisms underlying aquatic invasions, as well as their existing impacts and future risks. Here, we fill the knowledge gap by performing global-scale research targeting both marine and freshwater invaders.
First, we quantified changes in environments niche of marine invaders between native and introduced ranges. Across taxa, marine invaders showed limited niche expansion into novel environments, with more than 80% of invaders occupying broader native than introduced niches. Nevertheless, the magnitude of niche expansion increased with residence time, indicating that environmental occupancy increases with time after introduction.
Second, we proposed a framework that integrated the environmental niche and invasion process at both the species and the population level, and demonstrated how different dimensions of species niches can help in understanding the success and impact of non-native species. This framework was then applied to understand the invasion success of freshwater megafish: species with broader niches were more likely to be introduced, establish populations, and exert more severe impacts.
Third, based on environmental niche theory, we developed a risk framework for predicting invasion risks for 868 non-native marine animal species. We identified that invasion-risk hotspots across the Americas, Europe, the Middle East, East Asia and coastal Australia. Taken together, these findings can improve early warning, prioritization and management of aquatic biological invasions.