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Sharks are threatened by several human activities that impact their distribution and abundance. A great proportion of shark captures happen as incidental capture (bycatch) by fisheries and in beach nets. Recent studies have focused on reducing these captures by exploiting technologies that target the sharks' electrosensory system, obtaining contrasting results. This study investigates the effect of a strong neodymium magnet and pulsed magnetic fields (PMFs) on captive sand tiger sharks (Carcharias taurus) through the analysis of their behavioural responses. Firstly, individuals were presented with the magnet in combination with different types of food. The magnet did not influence the sharks' behaviours, while an effect of the food type emerged. Secondly, PMFs were generated through a pulsed electric current induced within a solenoid associated with a PVC structure. The PMFs affected some of the sharks' behaviours, both near (<2 m) and at a distance (>2 m) from the source. The results suggest that strong magnets are inefficient in deterring sand tiger sharks, while PMFs could be a promising alternative. This study confirms how the efficacy of shark repellents may be affected by factors such as the type of electrosensory stimuli, the species involved, and the context in which the interaction takes place. [ABSTRACT FROM AUTHOR]

Aurelia is a jellyfish genus common in coastal and estuarine habitats, that are typically affected by human pressures such as heavy metals contamination. Mercury is one of the most dangerous due to its high toxicity, persistence and bioaccumulation. In this paper, we tested for the first time the independent and combined effects of a level of mercury allowable by European regulation in force and hyposalinity on the asexual reproduction of Aurelia sp. polyps, mirroring a realistic scenario. Both mercury (0.07 µg/L, Maximum Allowable Concentration) and salinity (18 and 23 PSU) and the combination of the two factors stimulated the asexual reproduction increasing the number of polyps and buds during the 41 days of experiments. The increment of the asexual reproduction and the absence of suffering and mortality suggest that levels of mercury below the concentration fixed by the law and hyposalinity conditions could promote jellyfish proliferations, according to the hormesis hypothesis. [ABSTRACT FROM AUTHOR]

Sharks are globally exposed to several anthropogenic threats, which, in many cases, have severely reduced their distribution and have impacted populations. In the Mediterranean Sea, because of its long history of exploitation and the relatively short span of scientific monitoring, reconstructing shark baselines is challenging. Many vulnerable species declined in population abundance and geographic distribution before it was possible to adequately track these changes. Consequently, for many of these species, current conservation assessments are now suffering from a severe case of shifting baseline syndrome, whereby their historical occurrence in the area is questioned.The sand tiger shark (Carcharias taurus) is one of these cases. Characterized by high philopatry, restricted home range, and low interchange between populations, its Mediterranean population may have been severely impacted by the high historical fishing pressure in the region before scientific monitoring began.In this study, the history of the abundance and distribution of C. taurus in the Mediterranean Sea was reconstructed through a comprehensive search of occurrence records in the literature and in museum collections. Between 1810 and 2008, 31 occurrence records and 54 publications provided information on the presence of the species in the area. These records were sparse but systematic over time and indicated occurrence hot spots in the south‐western Mediterranean Sea and in the eastern Adriatic Sea.The presence of ten sightings of juveniles from a total of 18 sightings with length information suggested local parturition. Habitat and extinction models indicate that the area has suitable oceanographic conditions for the occurrence of the species and that the species cannot be considered extinct in the Mediterranean Sea. Our study suggests that there is still hope for the recovery of the species and underlines the crucial role of historical investigations to reconstruct the history of large elasmobranchs in the Mediterranean Sea. [ABSTRACT FROM AUTHOR]

Rare earth elements (REEs), also called lanthanides, are emerging contaminants worldwide, due to their unique physical and chemical characteristics that make them essential in a variety of industrial applications. However, there is still a gap in the knowledge of occurrence and accumulation of REEs in biota, and no investigations have yet been performed in penguin feathers, which have already been widely utilized as a non-invasive tool for the biomonitoring of trace elements. The concentrations of 16 REEs were investigated in a colony of Humboldt penguins (Spheniscus humboldti) housed at the Acquario di Cattolica (Italy). Multielement determination of REEs was performed by an Inductively Coupled Plasma-Mass Spectrometer after a microwave digestion of feathers. As this colony lives indoors in a controlled environment, it was the ideal choice for studying lanthanide occurrence in penguin feathers. Since there is a strict link between metal levels in feathers and the diet of penguins, their food (capelin) was also tested for REEs. Chondrite normalized values revealed the same pattern for REEs in feathers and fish, but REE concentrations were an order of magnitude higher in penguin feathers, demonstrating the suitability of this tissue as a bioindicator of REEs. Unlabelled Image • The levels of 16 REE were investigated in Spheniscus humboldti feathers and food. • REE concentrations were order of magnitude higher in penguin feathers than in food. • Feathers are a suitable tool to biomonitor the presence of REE in the environment. • REE levels were strictly related to penguins' diet. [ABSTRACT FROM AUTHOR]