The "lessepsian invasion" - A case study revisited

A case study of the Lessepsian invasion of the Mediterranean Sea was carried out during the 1970s by a Hebrew University of Jerusalem team that included Uzi Ritte and his research students. The study zoomed on two mollusk "trios" of mytilid bivalves and cerithiid gastropods, each including an invader, a closely related and ecologically similar indigenous Red Sea species and a Mediterranean indigenous competitor. This paper revisits the results, conclusions and projections made by the 1970s study in the context of a recent unified invasion biology framework, and in the view of the dynamic development of the Lessepsian invasion and research into it throughout the more than 30 years since the case study took place. The approach of studying "trios" to detect potential invaders and project the course of invasions has not been repeated in the Lessepsian system since the 1970s case study. But the findings that opportunistic life history traits linked with a match of habitat in the invaded range to a species ecological niche make this species a potential invader and enable it to coexist with an encountered competitor remain robust. Recent human-induced and other environmental changes in the Mediterranean have however highlighted a potential significance of propagule pressure in intensifying competitive exclusion and resource monopolization by the invader, to the point of potentially impacting the invaded ecosystem.