Tackling bioinvasions through awareness and motivation: a case study on blue crabs in the Bizerte Lagoon (Tunisia, southern Mediterranean Sea)

The Mediterranean Sea is a well-known bioinvasion hotspot, with an increasing number of non-indigenous species spreading and becoming established. Among them, blue crabs of the species Callinectes sapidus and Portunus pelagicus have recently called the attention due to their notable ecosystem impacts but also potential economic importance. We hereby first tackled these species through interdisciplinary approaches along the Africa's Mediterranean coast (Bizerte Lagoon, Tunisia). Molecular analyses assigned C. sapidus specimens to the Lineage 1 sensu Windsor et al. (2019), while revealed uncertainties, mismatches, and low genetic distances within the P. pelagicus species complex, suggesting that multilocus or complete mitogenomes approaches are still needed to shed light on the taxonomy and distribution of these species worldwide. Replies to questionnaires and participatory monitoring confirmed the scattered literature data available and revealed that both species have already col- onized the Bizerte lagoon and showed similar distributions, although Portunus segnis is more abundant and is pre- sumably sustained by the presence of nursery grounds. Awareness campaigns strongly contributed to improve the level of engagement of the local community, with low catch discards and crab taste ranked as "good" to "ex- cellent" mostly during the second phase of the project. Crab abundances significantly affected the general perception of the fishermen in considering these species as new promising fishing targets, although educational background also played a main role among the other investigated variables. As the Bizerte Lagoon hosts a wide and native biological diversity that historically sustains local communities through small scale fishery activities and aquaculture, ecosystem-based management strategies are urged ahead of the proliferation of alien species.