Population genetic structure of the Atlantic blue crab Callinectes sapidus indicates multiple introductions into Moroccan coastal lagoons

Abstract

The Atlantic blue crab, Callinectes sapidus, is globally recognized as one of the world's most important invasive marine species, with substantial ecological and economic impacts across Mediterranean and eastern Atlantic coasts. This study presents the first genetic characterization of C. sapidus populations along the Mediterranean and eastern Atlantic. It integrates newly collected mitochondrial COI (cytochrome c oxidase subunit I) sequences with global datasets to clarify its population structure and invasion pathways. A total of 110 specimens were collected from four Moroccan lagoons (Marchica, Merja Zerga, Oualidia, and Sidi Moussa) and analyzed alongside 599 sequences retrieved from GenBank. Moroccan populations exhibited high genetic diversity (Hd = 0.80-0.84; pi = 0.004-0.007; 8-11 haplotypes per site). Demographic reconstruction analysis revealed signatures consistent with recent population expansion in the invasive range along the Morrocan coastlines. Comparative analyses of native and other non-native populations highlight complex invasion dynamics suggesting multiple introduction events from the native range specifically from the North American coastline. The pronounced genetic differentiation of C. sapidus in its native range across the North and South American coasts is consistent with patterns observed in other widely distributed marine crustaceans.