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The diet of juvenile specimens of Raja radula from the Ionian Sea was investigated. The stomach contents of 43 specimens were analysed in order to evaluate composite index (IRI Index of Relative Importance). To assess feeding strategy and trophic niche width, prey-specific biomass plotted against frequency of occurrence and Levins index were used, respectively. The diet of juvenile specimens of R. radula consisted mainly of crustacean decapods followed by algae, polychaetes and molluscs. Among crustaceans, Liocarcinus spp. were the most important prey items, with four species with relatively high IRI values. Most specimens had been feeding on L. pusillus, L. depurator and polychaetes, but the variation of prey-specific biomass indicates that there is not a clear dominance of any prey and the value of niche width indicates a high variability in R. radula diet. Differences between sexes exists only in % IRI values related to Liocarcinus spp. The results indicate that R. radula feeds on a wide range of prey items, although crustaceans were the favoured food source. [ABSTRACT FROM AUTHOR]

The deep-sea can act as a sink for legacy contaminants such as organochlorines (OCs), causing damages in its inhabitants for their persistence and their prolonged effects in the organisms. HCB, DDT and its isomers, and 28 PCBs congeners were detected in muscle and embryonic tissues of three deep-sea chondrichthyes Chimaera monstrosa (n = 16), Dalatias licha (n = 12) and Etmopterus spinax (n = 51) sampled in Ligurian and Tyrrhenian Sea (Mediterranean Sea). Contaminant distribution in E. spinax and C. monstrosa was PCBs > DDTs ≫ HCB while in D. licha was DDTs > PCBs ≫ HCB. Statistically significant differences were highlighted in OC levels among the species, but no such differences were found among sexes. Ratios between DDT isomers highlighted an historical input of the pesticide in the environment. For the first time was also demonstrated maternal transfer in deep water chondrichthyes, specifically in E. spinax where was highlighted that transfer of contaminants increases with increasing compound's Log Kow., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Very little information is reported for parasites of cnidarians, therefore, the present work aimed to investigate parasitic infections in one of the most widespread jellyfish in the Mediterranean Sea, Rhizostoma pulmo. The goals were to determine prevalence and intensity of parasites in R. pulmo, identify the species involved through morphological and molecular analysis, test whether infection parameters differ in different body parts and in relation to jellyfish size. 58 individuals were collected, 100% of them infected with digenean metacercariae. Intensity varied between 18.7 ± 6.7 per individual in 0-2 cm diameter jellyfish up to 505 ± 50.6 in 14 cm ones. Morphological and molecular analyses suggest that the metacercariae belonged to the family Lepocreadiidae and could be possibly assigned to the genus Clavogalea. Prevalence values of 100% suggest that R. pulmo is an important intermediate host in the life cycle of lepocreadiids in the region. Our findings also support the hypothesis that R. pulmo is an important part in the diet of teleost fish, which are reported as definitive hosts of lepocreadiids, since trophic transmission is necessary for these parasites to complete their life cycles. Parasitological data may therefore be useful to investigate fish-jellyfish predation, integrating traditional methods such as gut contents analysis., (© 2023. The Author(s).)