In most cases invasive species are responsible for doing great damage to native species, even taking some of native species to the very brink of the extinction. But there are also some positive cases, where invasive species can coexist with native species, and one of these cases was discussed in a paper in "Ecology".
In order to prove that not all invasive species cause harm to native species researchers studied the Asian shore crab, which has proliferated along the Atlantic shore. The invasive Asian shore crab population has experienced significant growth in the last few decades.
Scientists have concluded that Asian shore crab has found a hospitable niche in its new habitat, and different to all expectations gets along with native species. While the crab has exploited the conditions set up by the native cordgrass and ribbed mussels that dominate the cobbled beach ecosystem, it does not appear to do so at the expense of other native species that call the shoreline home.
Still, this case is only an exception because very few environments will offer enough room for new invasive species without harming invasive species in the process. Many invasive species are predatory, and thus doing significant damage to native species, especially in environments where native species didn't have any natural predators until these species came.
Invasive species are not causing only huge environmental damage but also big economic damage, and according to WWF's estimates invasive species have cost marine and coastal activities including fisheries, aquaculture, industrial infrastructure and harbors around £31 billion in the last five years.
World still lacks global action to tackle this serious problem, and many native habitats with unique plants and animals are in danger of going extinct. The worst thing in this story is the fact that many people still fail to take this problem seriously.