Age and environment are the main drivers shaping the wild common sole (Solea solea) microbiota.

Microbiota plays an essential role in fish growth and health and may be influenced by the changing environmental conditions. Here, we explored the microbiota of wild common sole, one of the most important fishery resources in the Mediterranean Sea, collected from different areas in the North Adriatic Sea. Our results show that the sole microbiota differs from that of the surrounding environment and among the different body sites (gill, skin and gut). Gut microbiota composition showed to be strongly related to fish age, rather than maturity, sex or sampling site. Age-related shifts in gut microbial communities were identified, with increased abundances of Bacteroidia and Desulfobacteria, unveiling potential microbial proxies for age estimation crucial for fisheries management. Our results expand the limited knowledge of the wild common sole microbiota, also in the light of the potential usefulness of the fish microbiota as a tool for future stock identification and connectivity studies.

Occurrence of the Leech, Pontobdella muricata Linnaeus, on Elasmobranch Species in the Northern and Central Adriatic Sea.

This study provides a parasitological analysis of the elasmobranch species caught in the northern and central Adriatic Sea. Sixty-two marine leeches were recorded on 747 individuals of Raja clavata Linnaeus, 1758 (thornback ray), Myliobatis aquila Linnaeus, 1758 (common eagle ray), and Torpedo marmorata Risso, 1810 (marbled torpedo ray) caught in 56 hauls over a 5 yr period. All leeches were identified as Pontobdella muricata, which is a typical ectoparasite of benthic elasmobranchs. The prevalence of infection ranged from 7.11% on R. clavata to 12.00% on M. aquila. The intensity of infection, the preferential sites of attachment to the host, and the periodicity of infection were evaluated.