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BackgroundThe blue shark (Prionace glauca, Linnaeus 1758) is one of the most abundant epipelagic shark inhabiting all the oceans except the poles, including the Mediterranean Sea, but its genetic structure has not been confirmed at basin and interoceanic distances. Past tagging programs in the Atlantic Ocean failed to find evidence of migration of blue sharks between the Mediterranean and the adjacent Atlantic, despite the extreme vagility of the species. Although the high rate of by-catch in the Mediterranean basin, to date no genetic study on Mediterranean blue shark was carried out, which constitutes a significant knowledge gap, considering that this population is classified as “Critically Endangered”, unlike its open-ocean counterpart.MethodsBlue shark phylogeography and demography in the Mediterranean Sea and North-Eastern Atlantic Ocean were inferred using two mitochondrial genes (Cytb and control region) amplified from 207 and 170 individuals respectively, collected from six localities across the Mediterranean and two from the North-Eastern Atlantic.ResultsAlthough no obvious pattern of geographical differentiation was apparent from the haplotype network, Φst analyses indicated significant genetic structure among four geographical groups. Demographic analyses suggest that these populations have experienced a constant population expansion in the last 0.4–0.1 million of years.DiscussionThe weak, but significant, differences in Mediterranean and adjacent North-eastern Atlantic blue sharks revealed a complex phylogeographic structure, which appears to reject the assumption of panmixia across the study area, but also supports a certain degree of population connectivity across the Strait of Gibraltar, despite the lack of evidence of migratory movements observed by tagging data. Analyses of spatial genetic structure in relation to sex-ratio and size could indicate some level of sex/stage biased migratory behaviour.

AIM:To estimate the prevalence of small intestine bacterial overgrowth (SIBO) among patients with an earlier diagnosis of irritable bowel disease (IBS) in our geographical area, and to collect information on the use of locally acting non-absorbable antibiotics in the management of SIBO.

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In this contribution the checklist of chondrichthyans of Calabria (Central Mediterranean, southern Italy) is reported. Data presented is derived from twenty years of opportunistic and active surveys from 2000 to 2020. A total of 55 species of chondrichthyans is present in Calabrian seas: 33 sharks, 20 rays, and 2 chimaeras. These species represent approximately 62% of the total reported for the Mediterranean. Approximately 71% of Calabrian species have been reported in the Tyrrhenian Sea, 49% in the Ionian Sea, and 33% in the Strait of Messina. According to IUCN criteria, new records of Endangered and Critically Endangered species (i.e., Carcahrodon carcharias [Linnaeus, 1758], Lamna nasus [Bonnaterre, 1788], Cetorhinus maximus [Gunnerus, 1765], Mobula mobular [Bonnaterre, 1788], Sphyrna zygaena [Linnaeus, 1758]) are reported, together with the first record of Raya brachyura Lafont, 1873 for the Ionian coasts and probably third confirmed record of the rare chimaera Hydrolagus mirabilis (Collett, 1904) for the Mediterranean.