In the Mediterranean Sea, fish assemblages associated with seagrasses host a significant percentage of the total fish biodiversity and have been extensively studied. However, an overview of species richness and functional diversity at the Mediterranean scale was lacking, hindering the study of scale-dependent mechanisms related to fish habitat use and, ultimately, structuring ecological communities.

An exhaustive literature search was therefore implemented to build up a specific data base that includes the presence and the life stages of fish in the various seagrass habitats, along with specific functional traits known to be associated with fish habitat use and reproduction. The aim was to explore the extent to which fish species’ traits drive the functional composition of fish assemblages associated with seagrass habitats and to determine if differences in seagrass structural complexity may influence the functional strategies of associated fauna.

The meta-analytic approach es applied revealed that the high species richness of fish in seagrass meadows is unevenly distributed among different habitats, showing a nested structure. Almost all the observed species present in Posidonia oceanica, with progressively smaller subsets found in Cymodocea nodosa and Zostera sp.

The characterization of the functional space and structure of fish assemblages across the various seagrass habitats showed that Mediterranean seagrasses host a vast array of functionally similar fish species characterized by r-like reproductive strategies and low-to-intermediate trophic levels, but differ for the traits exhibited by the associated predators.

Our findings reinforce the view that the predominant use of seagrass habitats by fish might be driven by the trade-off between different reproductive and feeding strategies.

Elasmobranchs face significant threats from intensive fishing and by-catch, particularly in the Mediterranean Sea, where 53% of sharks and rays are at risk of extinction. Understanding their biology and ecological roles is crucial to develop conservation strategies. In the current study the trophic ecology of the blackspotted smooth-hound Mustelus punctulatus, listed as vulnerable by the International Union for the Conservation of Nature, has been studied in three areas of the North-central Adriatic Sea, the Gulf of Trieste (named zone A), Venice Lagoon (zone B), and Emilia-Marche (zone C), by means of stomach content (SCA) and stable isotope analyses (SIA). SIA were carried out on both muscle and vertebrae. Our results showed that Mustelus punctulatus feed mostly on crustanceans and bony fishes, especially small pelagics, and to a lesser extent polychaetes and molluscs, with significant differences in diet composition among specimens collected in the zone A and those from zone C. Concerning SIA, while the δ¹³C values in muscle tissue aligned with existing literature, a slight depletion in δ¹⁵N was observed across all samples, which could be attributed to increased water intake from the Po River, exacerbated by the significant flood in May 2023, as fishing pressure in the area has decreased in the last years. Moreover, by comparing δ¹⁵N values in the core and outer portions of vertebrae, corresponding to the mother's isotopic signature and prey assimilated within the last year, respectively, a clear ontogenetic shift in diet was observed. Remarkably, δ¹⁵N values in the core varied significantly among samples from the three zones, suggesting the presence of at least two distinct nursery areas in the northern Adriatic Sea. These findings underscore the importance of considering regional variations and ontogenetic shifts in elasmobranch ecology for effective conservation and management strategies.

Coralligenous habitat is a biogenic temperate reef, representing one of the most important biodiversity hotspots in the Mediterranean Sea. The iconic species Paramuricea clavata is an ecosystem engineer which increases the spatial complexity of the habitat, developing animal forests that support the persistence of other species. In the last decade, P. clavata suffered the increase of multiple stressors which led to mass mortality events with substantially unknown consequences on associated benthic assemblages. We tested the hypothesis that P. clavata has the role of increasing local biodiversity. The study was carried out in the Gulf of Naples, where benthic communities inside vs outside the forests were compared in terms of β-diversity (partitioned in its two components nestedness and turnover) and functional richness. P. clavata forests are mainly represented by small size classes and show a wide range of both density (27 - 65 colonies/m²) and biomass (100 - 505 g dry weight/m²). The assessment of benthic assemblages reveals P. clavata forests support distinct communities, characterized by higher compositional and functional richness compared to the adjacent zones. The analysis of functional groups reveals that P. clavata prevents the spread of algal species, favouring the growth of sessile invertebrates. Comparing β-diversity, the turnover component is statistically significant at both taxonomical and functional level with higher values within the forest, highlighting the important role of P. clavata in modifying local environmental conditions and driving local species distribution. Our results provide new insights to the ecological relevance of this habitat and point out the importance of implementing its protection.

Among coastal systems, river deltas are highly dynamic environments: they are hotspots of biodiversity, and they respond quickly to natural and human changes (Trincardi et al., 2023). In recent years, human impact on the Po River Delta (UNESCO heritage site and biodiversity hotspot) has significantly changed both the territory and the land use. Because of this, there have been major modifications in the type and amount of the ecosystem services that such area could offer to the local communities (Gaglio et al., 2017).

For five consecutive years (2015/2019) we sampled on a seasonal basis the macrozoobenthic community of the Po Delta (Emilia Romagna area) across all the microhabitats of the lagoons which responds optimally to natural and anthropogenic stressors (Mistri et al., 2000; Carvalho et al., 2011). We have demonstrated that the taxonomic and trophic-functional diversity of the same microhabitat (e.g., macroalgal beds, bare sediment, or Phragmites roots) is not comparable between different lagoons. Not only the macrozoobenthic communities are distinct, but the taxonomical and trophic biodiversity do not overlap either. The findings demonstrate the critical importance of conserving lagoon ecosystems in their microhabitat variability. Each lagoon system is unique, and preserving their distinct ecological characteristics is essential for maintaining their biodiversity and the ecosystem services they provide. Consequently, conservation strategies must prioritize the protection of these diverse microhabitats to ensure the long-term ecological integrity of the Po River Delta.

Bottom trawling is known to affect directly and indirectly the structure and functions of benthic ecosystems. Direct effects include the removal of benthic and benthopelagic species, whereas indirect effects include a wide range of impacts on the seabed and resident species. Among indirect effects, functional changes to benthic communities have also been reported, which in turn may affect the diet (i.e. food preferences and feeding habits) and the trophodynamics (i.e. trophic level in the food chain) of benthic-feeding fish. Here, we aimed to evaluate the impact of fishing pressure on the diet composition, trophic level and food source and lipid content of one of the most important commercial species of the Mediterranean Sea, the red mullet Mullus barbatus collected in three areas of the Central Adriatic Sea, characterized by different fishery pressure, according to Vessel Monitoring System data. Our results revealed significant differences in diet composition among areas, based on stomach contents analysis, suggesting that fishing activities influence the dietary preferences of red mullets, while δ¹³C and δ¹⁵N values did not reveal changes in carbon sources and trophic levels. Finally, significant differences were observed in the concentration of polyunsaturated fatty acids (PUFAs) and monounsaturated fatty acids (MUFAs) of specimen from the three areas and specifically areas with lower fishing pressure showed a higher concentration of healthy PUFAs, while areas with higher fishing pressure showed a higher concentration of MUFAs. The significant influence of this anthropogenic impact on the diet composition, stable isotopes contents and nutritional characteristics of M. barbatus underlines the importance of considering fishing pressure in fisheries management and also for maintaining a good nutritional quality of commercial marine species.

The Italian Spring Goby (Orsinigobius punctatissimus) is an endemic freshwater fish species considered Critically Endangered by the Italian IUCN committee. This species is closely associated with highly specific and isolated habitats, such as springs and oxbow lakes in the River Po plain, where Lombardy constitutes half of the species' range. Because of spring droughts, pollution, habitat loss and fragmentation, the species distribution in the freshwater ecosystems of Lombardy has been estimated being decreased by 70% in recent decades. However, information on the presence and ecology of this species is very limited because of the scarcity of monitoring activities in suitable habitats. For instance, the current knowledge about the habitat preferences of the species is outdated and based on past qualitative observations. Therefore, the aim of this study is to enlarge the knowledge on the ecology and distribution of the Italian Spring Goby in spring ecosystems of the Lombardy region. In spring-summer 2023 and 2024, we surveyed more than 130 springs spanned over a longitudinal gradient, collecting data on the presence of the species and fish community, as well as biotic and abiotic features of the spring. We found the species in 25 springs, corresponding to the 19% of the sampled sites. Results showed that the main predictive variables for the presence and abundance are morphological features such as substrate type, average depth, illumination, and retention of organic debris. This study provides novel insights into the habitat preferences of the Italian Spring Goby and its regional distribution.