Biological invasion of the non-indigenous Atlantic blue crab Callinectes sapidus and its symbionts in Moroccan coastal environments

Abstract

Crustaceans are a well-represented group in coastal environments. Their health is often linked to that of humans and together they are linked to the health of the environment. Such interconnection is the basis of the 'One Health' concept. Invasive non-native species may carry invasive parasites and/or enhance native parasites, leading to a loss of native biodiversity and to disease/mortality of indigenous species as well as risks to human health and the economy. The Atlantic crab Callinectes sapidus Rathbun, 1896, native to the western Atlantic, has been established in various Moroccan coastal ecosystems since 2017. It hosts several parasites both in native and introduced areas. As such, it constitutes a good model for understanding biological invasions in the context of the 'One Health' concept. The main objective of this study is to determine the origin and structure of Moroccan populations of C. sapidus, track their introduction pathways, and investigate the diversity of parasites. Knowledge about the symbionts associated with these populations will enable us to assess their effects on native biodiversity, associated marine diseases, and risks to human health. Overall, 110 specimens of C. sapidus from Morocco were analyzed, including 30 from the Marchica Lagoon (Mediterranean coast), and 80 specimens from the Atlantic coast (30 from Merja Zerga Lagoon, 30 from Sidi Moussa Lagoon, and 20 from Oualidia Lagoon). Molecular analyses were performed to investigated the genetic structure of C. sapidus populations from four Moroccan lagoons (Merja Zerga, Oualidia, Marchica, and Sidi Moussa). A 572bp fragment of the Cytochrome oxidase subunit 1 (COI) marker was sequenced, generating a total of 110 sequences. Haplotype network analysis, revealed a complex genetic structure among the Moroccan C. sapidus populations, and showed that Moroccan C. sapidus predominantly originates from populations along the eastern coast of the United States. Understanding these genetic patterns is crucial to assess the risk of future introductions, to evaluate the potential co-introduction of parasites, and to develop appropriate management strategies to mitigate the ecological and economic impacts of this ongoing invasion. The results also revealed the presence of the dinoflagellate Hematodinium perezi, a potential disease threat to native crustacean species.