Colonization Dynamics of Potential Stowaways Inhabiting Marinas: Lessons from Caprellid Crustaceans

Abstract

Despite the fact that stowaway transport is an increasingly common invasion pathway, its key ecological aspects, such as colonization dynamics of potential invaders on human transport vectors, are poorly understood. Considering that marinas may function as stepping-stone habitats for the spread of marine invaders, they provide a unique opportunity for understanding the first steps in the stowaway pathway. One of the dominant groups inhabiting marinas are caprellid crustaceans. These small invertebrates have demonstrated a high potential for introduction and establishment far beyond their distribution range. Here, we analyzed the colonization dynamics of caprellid species inhabiting marinas of Cadiz Bay (Spain) on plastic collectors and discussed their implications on invasion success. We found that collectors largely mirrored the resident caprellid community assemblages after just one month of deployment, showing that caprellid species inhabiting marina structures have a high capacity to colonize new artificial substrates. Moreover, the two non-indigenous species found, Caprella scaura and Paracaprella pusilla, successfully established dense and well-structured populations in the collectors (including all sex/age groups considered). We suggest a potential interplay between colonization ability and stowaway organisms' invasion success. Furthermore, collectors used are supported as a useful tool in the early detection of non-indigenous species and their monitoring in relation to resident species.