In the coastal environment, a large amount of microplastics (MPs) can accumulate in the sediments of seagrass beds. However, the potential impact these pollutants have on seagrasses and associated organisms is currently unknown. In this study, we investigated the differences in MPs abundance and composition (i.e., shape, colour and polymer type) in marine sediments collected at different depths (-5 m, -15 m, -20 m) at two sites characterized by the presence of Posidonia oceanica meadows and at one unvegetated site. In the vegetated sites, sediment samples were collected respectively above and below the upper and lower limits of the meadow (-5 m and -20 m), out of the P. oceanica meadow, and in the central portion of the meadow (-15 m). By focusing on the central part of the meadow, we investigated if the structural features (i.e. shoots density and leaf surface) can affect the amount of MPs retained within the underlying sediment and if these, in turn, can affect the associated benthic communities. Results showed that the number of MPs retained by P. oceanica meadows was higher than that found at the unvegetated site, showing also a different composition. In particular, at vegetated sites, we observed that MPs particles were more abundant within the meadow (at - 15 m), compared to the other depths, on unvegetated sediment, with a dominance of transparent fragments of polypropylene (PP). We observed that MPs entrapment by P. oceanica was accentuated by the higher shoots density, while the seagrass leaf surface did not appear to have any effect. Both the abundance and richness of macrofauna associated with P. oceanica rhizomes appear to be negatively influenced by the MPs abundance in the sediment. Overall, this study increases knowledge of the potential risks of MPs accumulation in important coastal habitats such as the Posidonia oceanica meadows.

Subadult flathead grey mullets (Mugil cephalus) were fed three experimental diets containing increasing percentages of partially defatted black soldier fly (Hermetia illucens, BSF) that proportionally replaced the protein sources in the reference diet. At the end of the feeding trial, fish growth and gut, liver and spleen histology were evaluated. BSF inclusion did not significantly affect growth performances in any dietary groups. However, Fulton’s condition factor was lower in fish who were fed diets with the highest replacement levels (15% and 20%; BSF15 and BSF20) compared to those fed the 10% replacement (BSF10) and the control diet (BSF0). Histological analyses revealed increased villi thickness and mucous cell proliferation in the intestine of fish from BSF10 and BSF15 groups. A significant worsening of intestinal condition was observed in fish from the BSF20 group. Liver histology was not affected, while a dose-dependent effect on spleen was observed in fish fed BSF inclusions. Despite the absence of enteritis signs, an increase in macrophages/like TNF-α+ cells in the intestine mucosa indicated immune stimulation in the BSF10 group. Results indicate, for the first time, a threshold for BSF meal inclusion in diets specifically formulated for flathead grey mullets. The BSF10 diet was optimal, as growth performance was not affected and intestine health improved at both morphological and innate immune system levels.

Ocean warming poses significant threats to coastal ecosystems. This study investigates the impact of thermal effluents from power plants, as proxies for climate-driven temperatures increase, on Posidonia oceanica meadows and associated fish communities. Using a gradient-based approach, we analyzed environmental variables, seagrass indicators, fish assemblages, and functional group (FG) dynamics across a thermal gradient extending from the effluent outfall itself. Results indicate that temperature is the dominant factor influencing P. oceanica, with reduced leaf length, shoot density, and rhizome weight characterizing samples closest to the effluent. Despite compensatory mechanisms, the overall photosynthetic biomass and resilience declined under thermal stress. Fish assemblages exhibited reduced species richness and biodiversity close to the thermal effluent, with opportunistic and thermophilic species dominating. An FG analysis revealed disrupted seasonal patterns, shifts in trophic dynamics, and functional compensation among species, highlighting potential ecological imbalances. Notably, transient predators thrived near the effluent, while more sedentary and temperate species were displaced. These findings underscore the cascading effects of rising temperatures on coastal habitats such as P. oceanica meadows and their associated communities, emphasizing the urgency for conservation measures. By identifying critical thresholds and adaptive responses, this study contributes valuable insights into the consequences of localized impacts of thermal stress on coastal biodiversity and ecosystem services.

Addressing the challenges posed by Non Indigenous Species (NIS) demands coordinated efforts across terrestrial, freshwater, and marine ecosystems. In this study, we used the Italian research network as a case study to identify and evaluate measures designed to enhance NIS research through a structured, interactive, and expert-driven strategy. The process began with a comprehensive evaluation of ongoing activities, research methodologies, and specific needs. This assessment informed the development of an initial set of proposals, which were collectively discussed and refined, leading to the identification of six good practices identified by the acronym TRACKS and described as: i) Tracking NIS in data collections; ii) Reference protocols for NIS data collection; iii) Active participation through citizen science and local ecological knowledge; iv) Collaboration in data sharing according to the FAIR principles; v) Knowledge Hub as centralized data repository for NIS data; vi) Strategic communication to raise public awareness and support public engagement. A SWOT framework was then applied to analyze the internal and external factors influencing the Strengths, Weaknesses, Opportunities, and Threats associated with each practice. Consensus-building techniques were used throughout the evaluation process to ensure the robustness of outcomes. Finally, a quantitative assessment of the SWOT analysis was conducted with 90 NIS experts working in terrestrial, marine, and freshwater ecosystems. This approach provided valuable insights into differing perceptions and enabled a clear presentation of six good practices to be consistently applied across NIS research systems.

Seahorses (Hippocampus spp.) are among the most popular marine species for wildlife tourism, being highly sought by divers and underwater photographers. Due to their unique morphology and behaviour, seahorses are particularly vulnerable to the visual and acoustic disturbances caused by underwater photographers, who often use flash photography to compensate for the seahorses' cryptic appearance. The present study utilises Opercular Beat Rate (OBR) as a non-invasive method to evaluate the stress induced by underwater tourism activities on Mediterranean seahorses, specifically the long-snouted Hippocampus guttulatus and the short-snouted H. hippocampus. In-situ experiments were conducted on both species, which are commonly found at dive sites throughout the Mar Piccolo of Taranto (MPT) in Apulia, Italy. The OBR was assessed across all four seasons and in both sexes, under both natural and stress-inducing conditions. The results indicate that stress from underwater photography affects both Mediterranean seahorse species, as evidenced by acute alterations in their ventilation rates. Unlike the behaviour exhibited by other seahorse species, the opercular beat rate of Mediterranean seahorses decreases during periods of stress. In H. guttulatus, this decrease may serve as a defensive mechanism, leading to instances where ventilation rates cease completely, resembling thanatosis.

Rising sea temperatures, driven by climate change, pose significant threats to coastal ecosystems. This study investigates the impact of thermal effluents from power plants, as proxies for climate-driven temperature increases, on Posidonia oceanica meadows and associated fish communities. Using a gradient-based approach, we analyzed environmental variables, seagrass indicators, fish assemblages, and functional group (FG) dynamics across a thermal gradient extending from the effluent outfall itself. Results indicate that temperature is the dominant factor influencing P. oceanica, with reduced leaf length, shoot density, and rhizome weight characterising samples closest to the effluent. Despite compensatory mechanisms, the overall photosynthetic biomass and resilience declined under thermal stress. Fish assemblages exhibited reduced species richness and biodiversity close to the thermal effluent, with opportunistic and thermophilic species dominating. FG analysis revealed disrupted seasonal patterns, shifts in trophic dynamics, and functional compensation among species, highlighting potential ecological imbalances. Notably, transient predators thrived near the effluent, while more sedentary and temperate species were displaced. These findings underscore the cascading effects of rising temperatures on coastal habitats such as P. oceanica meadows and on their associated communities, emphasizing the urgency for conservation measures. By identifying critical thresholds and adaptive responses, this study contributes valuable insights into the consequences of localized impacts of thermal stress on coastal biodiversity and ecosystem services.