In addition to their historical relevance, underwater sites of cultural heritage (e.g., shipwrecks, archeological sites) represent secondary habitats for marine life. However, despite a growing interest in their ecological role, studies focusing on these artificial environments remain limited. In this study, we performed the first systematic assessment of the marine biodiversity associated with the submerged structures of the ancient roman port of Egnazia. In particular, we conducted a seasonal (summer 2022 and winter 2023) comparative analysis of the qualitative and quantitative variations in the observed nektonic and benthic taxa between the submerged piers and two surrounding control areas. For benthopelagic and vagile benthic taxa, two seasonal samplings with four transects (of 10 m × 4 m) and three replicates per transect were conducted to analyze taxon diversity, abundance, and variability of individual size. The photo-quadrat method was employed to characterize sessile benthic taxa, using PVC frames measuring 40 cm × 40 cm, randomly placed on the study substrates with 20 replicates for each pier and the two controls. Our results highlight the occurrence of 75 taxa (67 associated with the submerged piers and 63 with the surrounding control areas), including 17 benthopelagic species, 26 vagile benthic and 32 sessile benthic taxa. Overall, our findings highlight that the submerged ancient structures of Egnazia represent a stable and functional marine habitat, promoting an increase in the local biodiversity and abundance of individuals of different species.

Strobilurin fungicides are among the most widely used agrochemicals worldwide. Dimoxystrobin has been shown to induce hepatic injury in adult zebrafish; however, whether this damage also involves early extracellular matrix remodelling and hepatobiliary remodelling remains unknown. Here, we investigated early remodelling of the extracellular matrix, focusing on initial collagen deposition and glycosaminoglycan redistribution after a short-term exposure (96 h) to two environmentally relevant concentrations of dimoxystrobin (6.56 and 13.13 µg/L) on the liver of Danio rerio using an integrated histological, histochemical, and semi-quantitative approach. The results showed a progressive dose-dependent alteration of hepatic architecture, accompanied by a significant increase in bile pigment-like deposits and collagen deposition. Exposure also induced a significant increase in the deposition of acidic glycosaminoglycans and a severe depletion of glycogen-dependent Periodic Acid–Schiff positivity components, accompanied by an increase in amylase-resistant Periodic Acid–Schiff reactive components. Overall, these findings indicate that dimoxystrobin-induced hepatotoxicity extends beyond parenchymal degeneration to encompass coordinated stromal and hepatobiliary remodelling. The present study also indicates that the periductal microenvironment may represent a sensitive target of dimoxystrobin toxicity and supports the use of histochemical and semi-quantitative analyses as sensitive tools for detecting sublethal pesticide-induced early extracellular matrix remodelling in fish liver.

Interspecific associations between fishes can generate complex behavioural interactions, yet their occurrence and functional significance in temperate marine systems remain poorly documented. Here we describe a previously unreported case of host‐associated behaviour involving juvenile Caranx crysos and schools of juvenile Sarpa salpa in coastal Mediterranean habitats. Associations were recorded exclusively in C. crysos individuals ≤ 15 cm TL, suggesting a size‐ and context‐dependent pattern of association with the host schools. Juvenile C. crysos integrated into S. salpa schools by adopting spatial positioning and behavioural patterns consistent with social mimicry. This association may provide antipredator advantages through group integration, while also allowing opportunistic foraging on benthic organisms and resuspended organic particles generated during host grazing activity. In rare cases, multiple individuals of C. crysos co‐occurred within the same school, producing aggressive interactions and indicating intraspecific competition for access to the host aggregation. From the host perspective, S. salpa exhibited only brief and limited behavioural responses, with no evidence of persistent exclusion or disruption of schooling behaviour, suggesting a low‐cost, largely tolerated interaction. Overall, our observations suggest the occurrence of a host‐related behavioural strategy in juvenile C. crysos that combines group integration, commensalistic and opportunistic feeding and intraspecific competition, likely shaped by ontogenetic constraints. These results highlight a previously overlooked level of behavioural complexity in temperate fish assemblages and suggest that fine‐scale interspecific interactions in Mediterranean coastal ecosystems may be more widespread than currently recognised.