Biological invasions occur when a species enters and spreads into areas beyond its natural range of distribution. Every single day thousands of marine species are transported by human activities around the world far away from their native range to new areas where they become non-indigenous species (NIS). However, whether this introduced species will be successful in its new host habitat is a dynamic, very complex process entailing several transitional stages. When successful, invasions may be among the greatest threats to global biodiversity