Free Pass Through the Pillars of Hercules? Genetic and Historical Insights Into the Recent Expansion of the Atlantic Blue Crab Callinectes sapidus to the West and the East of the Strait of Gibraltar

Abstract

The invasive Atlantic blue crab Callinectes sapidus has considerably extended its distribution along the Gulf of Cadiz and Moroccan coasts in the northeast Atlantic. This could indicate a new introduction event in the Gulf of Cadiz from the native area, in case of detectable genetic differences from the Mediterranean Sea populations. To test this and reconstruct the invasion, we assessed the genetic structure of crabs in the Gulf of Cadiz and Alboran Sea. We used sequences of the mitochondrial gene cytochrome c oxidase subunit I (COI), in almost its full length (1511 basepairs), of 149 individuals from three sites along the Spanish Mediterranean coast, two in the Alboran Sea, and two in the Gulf of Cadiz. Our data reveal low genetic variability, with only two haplotypes (here referred to as CSWM1 and CSWM2), compared to its known high genetic diversity in the native range, indicating a strong founder effect in the study region. Here we document an inversion of haplotype predominance between regions, haplotype CSWM2 being dominant in most of the Spanish Mediterranean coast, but less frequent in the Gulf of Cadiz and Alboran Sea. This suggests a secondary introduction of propagules into the investigated area, rather than a new introduction from the native area, nor a natural westward expansion with environmental selection of one haplotype over the other. Further studies with additional populations would help to better unveil the history of yet another invasive species in the Gulf of Cadiz.

New Records of Callinectes sapidus (Crustacea, Portunidae) from Malta and the San Leonardo River Estuary in Sicily (Central Mediterranean)

“…This BOLD BIN has an average p-distance of 1.57%, with the maximum p-distance within the BIN being 5.52%. The haplotype identified in this study matched 100% with the specimens from lineage 1, as identified in Rodrigues et al [51] and Windsor et al [52] in its native range, while matching to CSWM1, which is the most common haplotype for the specimens in Spain, along its Atlantic and Mediterranean coast, as identified by González-Ortegón et al [53], as well as other regions of the Mediterranean Sea, including Albania, Italy and Turkey, as identified in Schubart et al [33] (Figure 3). CSWM1 and CSWM2 are the two main haplotypes identified in the Mediterranean and represent various specimens from the region [33,46].…”

“…Another lineage is mainly found in the Caribbean Sea, with some overlapping at the southern regions of the first lineage, while the third lineage is restricted to Brazil [51,52]. These two studies show that in its native range, C. sapidus is characterised by a high level of genetic diversity; however, in the Mediterranean and the Black Sea, it is characterised by low genetic diversity, with all recorded COI haplotypes being related to the first lineage [33,53,70]. These observations indicate that introductions into the Mediterranean and the Black Sea are of North Atlantic origin or from the Gulf of Mexico.…”

“…These observations indicate that introductions into the Mediterranean and the Black Sea are of North Atlantic origin or from the Gulf of Mexico. In the Mediterranean Sea, almost all specimens of C. sapidus genetically group within two haplotypes, CSWM1 and CSWM2 [33,53], except for the specimens from Turkey, which tend to exhibit different haplotypes and have a higher level of genetic diversity, possibly linked to stocking events [33]. In our study, we only found specimens belonging to CSWM1, which is the most common haplotype for the Mediterranean Sea [33,53], thus showing that the specimens analysed in this study are unlikely to be new reintroductions into the Mediterranean Sea but rather range from the expansion of already present populations in the region.…”

Diet of the Invasive Atlantic Blue Crab Callinectes sapidus Rathbun, 1896 (Decapoda, Portunidae) in the Guadalquivir Estuary (Spain)

“…Invasive species disrupt the functioning of ecosystems and the trophic processes in which they rank the most significant disruptors of established ecological networks (Wainright et al 2021). The invasive Atlantic blue crab Callinectes sapidus Rathbun 1896, (Decapoda, Portunidae), native to the east coast of North and South America, has rapidly dispersed along the western Euro-African area since the mid-2010s (Mancinelli et al 2021;Encarnação et al 2021;González-Ortegón et al 2022;Chairi and González-Ortegón 2022) and is known for multiple ecological impacts in areas of the Mediterranean Sea where they have been established for a long time (Mancinelli et al 2017b).…”

Aquatic species shows asymmetric distribution range shifts in native and non-native areas

“…Nevertheless, at higher abundances, the Atlantic blue crab may be able to limit the invasion of the European green crab in North America (DeRivera et al, 2005). In Europe, and particularly in the Gulf of Cadiz, the native European green crab does not seem to represent a threat to the Atlantic blue crab because it has become a successful invader in locations where native crabs are abundant (Rodrıǵuez et al, 1997;Oliveira et al, 2000;Sprung, 2001;Encarnacão et al, 2013;Morais et al, 2019;Gonzaĺez-Ortegoń et al, 2022). The Atlantic blue crab has also become a profitable fishery in local fishing communities in Portugal, Spain, Greece, Turkey, and Tunisia (Nehring, 2011;Mancinelli et al, 2017;Vasconcelos et al, 2019;Encarnacão et al, 2021a;Clavero et al, 2022).…”