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The contribution of non-indigenous species to the transfer of contaminants in invaded food webs represents an active research area. Here we measured trace metals and CN stable isotopes in five populations of the invasive Atlantic blue crab Callinectes sapidus and in baseline bivalve species from Spain, Italy and Greece. They were used to estimate trophic transfer effects and the trophic position and isotopic niche of C. sapidus. Maximum trophic transfer effects occurred where the crab showed the largest isotopic niches and highest trophic positions; furthermore, the consistency of trace metal profiles between bivalves and crabs co-varied with the trophic position of the latters. Omnivory may influence the success of an invasive species, but also limit its effectiveness for biomonitoring. However, our results indicated that stable isotopes analysis provides a clarifying background where to cast patterns of contamination of the blue crab as well as of other omnivorous biomonitor species., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The Atlantic blue crab Callinectes sapidus is a portunid native to the western Atlantic, from New England to Uruguay. The species was introduced in Europe in 1901 where it has become invasive; additionally, a significant northward expansion has been emphasized in its native range. Here we present a harmonized global compilation of C. sapidus occurrences from native and non-native distribution ranges derived from online databases (GBIF, BISON, OBIS, and iNaturalist) as well as from unpublished and published sources. The dataset consists of 40,388 geo-referenced occurrences, 39,824 from native and 564 from non-native ranges, recorded in 53 countries. The implementation of quality controls imposed a severe reduction, in particular from online databases, of the records selected for inclusion in the dataset. In addition, a technical validation procedure was used to flag entries showing identical coordinates but different year of record, in-land occurrences and those located close to the coast. Similarly, a flagging system identified entries outside the known distribution of the species, or associated with unsuccessful introductions.

This study provides a baseline assessment of cadmium, copper, iron, manganese, lead, and zinc concentrations in muscles, gills, and exoskeleton of the Lessepsian blue swimming crab Portunus segnis captured in the Gulf of Gabès (Southern Mediterranean Sea, Tunisia) in November 2015. Furthermore, the species' trophic position is estimated using CN stable isotope analysis. The exoskeleton showed the lowest metal contents; in soft tissues, the essential Cu, Fe, and Zn and the non-essential Cd, Mn, and Pb showed the highest and lowest concentrations, respectively. The crab was characterized by a trophic position of 3.32, confirming its carnivorous trophic habits. Compared with literature data on invertebrate and fish species from the same area, Cd and Pb resulted remarkably low in the crab's soft tissues, while a food web-scale dilution effect was indicated. The need of a comprehensive assessment of the ecological impact of Portunus segnis in invaded Mediterranean waters is discussed., (Copyright © 2018 Elsevier Ltd. All rights reserved.)