Colonization of the Mediterranean Sea by the Lessepsian invasive jellyfish Cassiopea andromeda (Forskål, 1775) – a systematic review

The colonization of the Mediterranean Sea by Cassiopea andromeda underscores the complex interaction of biological, environmental, and anthropogenic factors influencing the spread of invasive species. This study describes the dispersal of C. andromeda across the Mediterranean basin and updates its current distribution. Starting from the initial introduction via the Suez Canal, we uncovered key stages of colonization across the Mediterranean, and discussed the role that salinity, dispersal vectors, and local genetic adaptations might have had in shaping its distribution. Through a comprehensive review of historical records, environmental parameters, and life cycle constraints, we identify three distinct colonization periods: a slow initial colonization, a rapid expansion phase, and a restricted westward spread, culminating in its appearance in the Mar Menor coastal lagoon in southwestern Mediterranean. Our findings suggest that salinity could have acted as a modulator of the spread velocity, delaying colonization in suboptimal conditions and potentially driving local adaptations. This work highlights the synergistic effects of anthropogenic activities and environmental stressors on the spread of marine invasives, providing insights to develop management strategies for C. andromeda and other invasive species in coastal ecosystems.