We studied the possible metal offloading onto the progeny of three pregnant female ragged-tooth sharks (Carcharias taurus) (C. taurus). The presences of five metals, i.e. aluminium (Al), arsenic (As), cadmium (Cd), lead (Pb) and selenium (Se) were validated by mass spectrometry in the maternal plasma as well as the intracapsular and uterine fluids (UF) in which embryos develop. Metals were ranked in a decreasing concentration as follows: Plasma: As > Al > Se > Pb > Cd; ICF: As > Se > Al > Cd > Pb and UF: As > Se > Al > Cd > Pb. As was present in the highest concentration in all three sharks. Al, Pb and Cd were found to be the highest within the plasma, while concentrations of Se were similar in all three fluids. These results indicate that C. taurus embryos are exposed to metals during early development, but the impact of this exposure remains unknown. To the best of our knowledge, this is the first investigation to confirm the presence of metals in the fluids that surround the developing C. taurus embryos, a species that is already listed as vulnerable.

Blubber is a highly specialized and dynamic tissue unique to marine mammals and presents a reflection of the individuals' nutrition, environment, and life history traits.Few studies have investigated the histomorphology of cetacean blubber in subtropical environments. The aim of this study was to investigate the blubber histomorphology of three different dolphin species off the subtropical KwaZulu-Natal coast, South Africa, using adipocyte cell size, number, and density. Blubber tissue samples from the saddle area of 43 incidentally bycaught animals (four Sousa plumbea, 36 Tursiops aduncus, and three Delphinus delphis) were used to compare cell parameters between blubber layers. Samples were divided into the upper third (corresponding to the superficial layer closest to the epidermis), middle third, and lower third (corresponding to the deep layer). For T. aduncus, factors potentially affecting blubber histomorphology, such as sex, age class, and season, were also assessed. Our results showed that no stratification was present in S. plumbea, which could be ascribed to the species' warmer inshore habitat, large body size, and apparent lower mobility. For T. aduncus and D. capensis, however, blubber stratification was determined, characterized by a gradual transition of cell size, number, and density between layers rather than clearly defined layers. Significant differences in adipocyte cell number and density were found for different sexes and age classes of T. aduncus. However, there were no significant differences between seasons, which was attributed to the small temperature differences between seasons. This study represents the first investigation of odontocete blubber histomorphology in subtropical waters. It is recommended that future studies investigate blubber lipid content, while also taking into consideration the reproductive status of the females and the temperature range of their study area.It is hoped that our results, in conjunction with histopathology and other health indicators, could assist in assessing health and body condition.

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The extreme sparsity of collection efforts in many parts of the word, including southern Africa, leaves a vast hidden diversity of marine cestode species, such as species of Phoreiobothrium. The investigation of a common South African coastal-pelagic species, the spinner shark Carcharhinus brevipinna (Valenciennes) resulted in the discovery of a new species of Phoreiobothrium Linton, 1889. Phoreiobothrium martini n. sp. is undoubtedly different from all other congeners in several morphological characteristics, however, it is most easily distinguished from other species by the size of its hooks.Furthermore, this species is peculiar in the sense of its microthrix pattern. It only possesses litriches on its proximal bothridial surface. Additionally, P. martini n. sp. also displays a scarcity of gladiate spinitriches on its cephalic peduncle. This has not been recorded in any other congener within this genus and could resemble a new, generic characteristic. The addition of P. martini n. sp. increases the total number of valid species of Phoreiobothrium to 18 worldwide. Furthermore, P. martini n. sp. marks the description of representatives of only the second onchoproteocephalidean genus from southern Africa, therefore expanding the generic biogeographical representation and introducing new host associations.Apart from the description of this new species of cestode, the discovery of P. martini n. sp. as well as additional species of Phoreiobothrium is bene cial regarding future ecological investigations. With the high degree of host-speci city found amongst species of Phoreiobothrium, species such as P. martini n. sp. could be used as sentinel species for the accurate identi cation, separation and diagnosis of commonly misidenti ed shark species, such as C. brevipinna and C. limbatus (Valenciennes).host species (Caira et al. 2017; Alijanpour Darvishsi & Haseli 2019). Species of Phoreiobothrium are known to explicitly parasitise sharks, with the majority (11/17) infecting sharks of the family Carcharhinidae, whilst the remainder (6/17) infect sharks from the family Sphyrnidae Caira et al. 2021). Information regarding the life-cycles of cestodes belonging to this genus is however still insu cient (Caira & Reyda 2005;Jensen 2005). This is due to the fact that these cestodes often mature in their relevant elasmobranch hosts species (Jensen & Bullard 2010). Larval Phoreiobothrium found to parasitise the intermediate hosts, such as teleost shes, do not resemble the morphology of their adult stages (Caira & Reyda 2005;Jensen & Bullard 2010). Consequently, larval cestodes of this genus cannot accurately be assigned to species-level without the aid of molecular sequence data.Given that the de nitive hosts of the 17 currently accepted species of Phoreiobothrium only represent 21% (11/52) of recognised carcharhinid and 66% (6/9) of sphyrnid shark species (Froese & Pauly 2021;Caira et al. 2021), several species await scienti c discovery. There are also sparse collection efforts of speci c hosts for parasitic research in many part...