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Elasmobranchs play crucial roles as predators in marine ecosystems. Understanding their trophic strategies and interactions is necessary for comprehending food web dynamics and developing ecosystem-based management strategies. Although, feeding strategies can change depending on several factors, including fluctuations in prey availability throughout the year. In this study, we investigated the trophic ecology of the pelagic stingray, Pteroplatytrygon violacea , the only stingray inhabiting the pelagic environment in the western Mediterranean Sea. We found significant temporal differences in diet composition, mostly consuming pelagic zooplankton in spring, whereas benthopelagic teleosts in autumn. After contrasting different studies, P. violacea appears to have a generalist and opportunistic diet consisting of a broad spectrum of pelagic and benthopelagic species, and trophic plasticity in response to environmental fluctuations. Our findings suggest that P. violacea can present different feeding strategies, mainly pelagic, with a relatively low trophic position for a mesopredator compared to other batoids. • Understanding feeding ecology is essential for effective conservation management. • The diet composition of P. violacea changes in time according to prey availability. • Pteroplatytrygon violacea has a generalist and opportunistic feeding behaviour. • Pteroplatytrygon violacea presents different feeding strategies, mainly pelagic. [ABSTRACT FROM AUTHOR]

Studying the feeding ecology of an organism is essential to understanding its ecological role in the ecosystem. Although the small-spotted catshark ( Scyliorhinus canicula ) is widely studied, most feeding studies have been conducted using invasive techniques, such as the analysis of stomach contents. Moreover, information from the Mediterranean Sea is surprisingly scarce and not up to date. Here, we studied the feeding ecology of the small-spotted catshark in the northwestern Mediterranean Sea using stable isotopes (nitrogen and carbon isotopic values) from blood samples, with individuals released alive in the area of capture after sampling. In overall for the population of small-spotted catshark, the isotopic values were −19.01 ± 1.12‰ and 8.03 ± 0.61‰ for δ 13 C and for δ 15 N, respectively. Results reveal a diet mainly composed of euphausiids, with sex and size variations. Results confirm the ecological role of the small-spotted catshark as a mesopredator, which holds a trophic position similar to skates and rays in the study area, but lower than the other demersal and pelagic sharks analysed. The trophic behaviour of the small-spotted catshark indicates its high trophic plasticity, which could allow this species to thrive in highly exploited environments. Our methodological approach, which did not damage the target species, presents new possibilities for conducting ecological studies with other elasmobranchs in the Mediterranean Sea, a highly exploited area that hosts many threatened and rare species. [ABSTRACT FROM AUTHOR]

Knowledge of marine predator trophic ecology is essential for defining their ecological role and trophic position in ecosystems. Based on their trophic habits, sharks and batoids occupy higher and medium trophic levels in the food webs, although differences in the trophic preferences exist between species. They are important organisms in marine ecosystems by maintaining the species below them in the food chain and serving as an indicator for ocean health. In comparison to sharks, batoids usually receive less research attention, with very little diet information available. This is true of the speckled ray (Raja polystigma), one of the three endemic batoids in Mediterranean waters. Here, by combining analyses of stomach contents and stable isotopes, we examined the trophic ecology (dietary composition and trophic position) of this ray in the north-western Mediterranean Sea. We also compared its trophic niche with the trophic position of other sympatric elasmobranchs present in same marine ecosystem. The results revealed that R. polystigma mainly consumes shrimps and to a lesser extent crabs, fin-fish, cephalopods, polychaetes and, surprisingly, small demersal sharks. We also found that R. polystigma shows similar trophic position to other crustacean-consumer elasmobranchs such rays and small demersal sharks. The results of this study provide new insights into the ecological role of this endemic ray species in the Mediterranean Sea. • Batoids are important organisms in marine ecosystems. • Little information exists about the trophic role of batoids. • The trophic ecology of an endemic ray was examined. • Speckled rays arecrustacean-specialists. • Speckled rays exhibit share trophic positions with other sympatric crustacean-consumer elasmobranchs. [ABSTRACT FROM AUTHOR]

The study of the feeding ecology of marine organisms is crucial to understanding their ecological roles and advancing our knowledge of marine ecosystem functioning. The aim of this study was to analyse the trophic ecology of two demersal predator species, black anglerfish ( Lophius budegassa ) and white anglerfish ( L. piscatorius ), in the northwestern Mediterranean Sea. Both species are important in the study area due to their high abundance and economic value, but information about their feeding behaviour is scarce. Here, we described the diet composition and ecological role of these two species, investigating whether trophic segregation exists between them and amongst fish of different sizes. In addition, by using experimental survey data we described the spatial distribution of both species to help us interpret trophic behaviour patterns. We gathered samples of two different sizes (small individuals of a total length <30 cm and large individuals ≥30 cm) of both species and combined stomach content analyses (SCA) and stable isotope analyses (SIA) of nitrogen and carbon with isotopic mixing models. Our results revealed that both anglerfish species are opportunistic predators, showing a diet composed mainly of fishes and, to a lesser extent, of crustaceans, with a small proportion of cephalopods, gastropods, bivalves and echinoderms. We found trophic segregation between the two species and the two sizes, indicating that they feed on different prey, in line with differences in their spatial distribution within the study area. This partial partition of food resources could also be explained by the differences in rhythms of activity that were reported in previous studies. In addition, although both species occupied a high position within the food web, our results showed that white anglerfish individuals and the large-sized fish of both species held higher trophic positions. This study demonstrates the usefulness of complementary approaches for trophic studies and confirms that both anglerfish species play an important role as predators in the northwestern Mediterranean Sea food web. [ABSTRACT FROM AUTHOR]