The Westernmost Record of the Invasive Isopod Mesanthura romulea from the Moroccan Coast of the Mediterranean Sea: An Overview of Its Spread

The expansion of international maritime trade, commercial shipping, and cruise tourism over recent decades has significantly accelerated vector-mediated biological introductions into the Mediterranean Sea. Port infrastructures and recreational marinas act as critical regional hubs, driving the introduction dynamics and secondary stepping-stone node dispersal of non-indigenous species (NIS). During a field monitoring survey for alien marine fauna along the Mediterranean coast of Morocco, an anthurid isopod identified as Mesanthura romulea Poore & Lew Ton, 1986 was detected for the first time in the Marina of Saidia. This finding represents the first record of the species for Morocco and its westernmost occurrence along the southern Mediterranean coastline. This study compiles and evaluates the chronological and spatial expansion of M. romulea across the Mediterranean basin over a twenty-five-year timeline (2000–2025). Despite its rapid proliferation, quantitative assessments regarding the ecological and socio-economic impacts of M. romulea on native ecosystems remain starkly absent, constituting a critical knowledge gap for regional marine conservation. Consequently, future research must urgently transition from spatial tracking to impact quantification and functional ecology, utilizing field exclusion experiments and trophic niche analyses. Finally, monitoring programs should integrate targeted molecular approaches and optimize adaptive marine management strategies across the increasingly vulnerable North African coastline.