Massive infection of Cystidicoloides ephemeridarum in brown trout Salmo trutta with skeletal deformities.

We investigated the cause of skeletal deformities found in brown trout from the Aspromonte mountain area in Reggio Calabria, Italy. Toxicological, histopathological and parasitological analyses were carried out on 14 fish with evident macro-morphological alterations from 2 different locations in the same river, and 4 control fish without morphological alterations from a different river (far from the first river but still within the area under study). Histopathological and radiological observations confirmed severe skeletal deformities in the specimens investigated. Parasitological examinations highlighted the presence of the nematode Cystidicoloides ephemeridarum, found only within the gastrointestinal tract of specimens showing deformities. Moreover, a direct correlation between parasite number and fish size was found. Given the low heavy metal levels and the presence of a massive parasitosis in teleosts showing deformities, we postulate a correlation between skeletal deformities and nematode infestation: the parasites caused a serious vitamin and mineral deficiency in the fish, which led to a dysplastic vertebral column. The low calcium levels found in malformed specimens compared with negative controls effectively confirm this hypothesis.

Merkel cells immunohistochemical study in striped dolphin (Stenella coeruleoalba) skin.

Cetacean mechanical senses, such as hearing, echolocation, active touch and the perception of water movements, are essential for their survival. Dolphins skin possesses dense packing of dermal papillae associated with the cutaneous ridges that suggests a sensory function, furthermore they are well innervated and very sensitive to touch. This is mediated by mechanoreceptors, abundant in the region of the head and in the dorsal part of the body. Most odontocetes possess vibrissae (i.e., sensory hair) that have been well described in literature and present a microanatomy similar to that of terrestrial mammals. The aim of this study was to characterize Merkel cell through use of specific antibodies: Substance P, Anti-calbindin DK28, Anti-5HT, Leu- enkephalin, Protein Gene Product 9.5 (PGP9.5) and Anti-Human Neuronal Protein, for the first time. Merkel cells (MCs) in the dolphin skin are specialized skin receptors, characterized by their particular location and close association with nerve terminals. The presence of neuroendocrine markers and different neuropeptides confirms that MCs play also neuroendocrine function and are considered as part of the diffuse neuroendocrine system. Furthermore, the presence of Leu-enkephalin in Merkel cells could involve these cells in inflammatory responses in the skin.

Microplastics occurrence in the Tyrrhenian waters and in the gastrointestinal tract of two congener species of seabreams.

In this work it is reported for the first time the characterization of microplastics from sea water samples and in two congener species of seabreams: Pagellus erythrinus and P. bogaraveo, Mediterranean fish species of great commercial importance. An experimental survey was conducted on May-June 2017 in the southernmost part of the Tyrrhenian Sea. Microplastics found in the sea water and in the grastrointestinal tract of two teleosts were characterized by Raman and IR spectroscopies. Microplastics found in sea water samples appeared in the form of fragments made of plastics of low and high density (PVC and LPDE). All the microplastics found in fish belonged to Nylon 66, typical fibers used in industry and in fisheries. Our findings highlighted the importance of further studies along the food web chain for a better understanding of the diffusion and possible consequences of this terrible threat.

Immunohistochemical characterization of epidermal dendritic-like cells in giant mudskipper, Periophthalmodon schlosseri.

Giant Mudskipper, Periophthalmodon schlosseri (Pallas, 1770), is euryhaline, amphibious, and air-breathing fish. These fishes live in close association to mangrove forests and often spend over 90% of time out of water, in adjacent mudflats. They have developed morphological and physiological adaptations to satisfy their unique lifestyles. The skin is the primary interface between the body and the environment, and has a central role in host defence. The initiation of immune responses to antigens in the vertebrate skin has often been attributed to epidermal Langerhans'cells (LC) that are dendritic cells (DC), antigen-presenting cells (APC) which reside in the epidermis. Dendritic cells have been characterized morphologically and functionally in the teleost fish tissues such as rainbow trout, salmonids, medaka, African catfish and zebrafish. However, there is no evidence of the presence of DCs and their role in mudskippers immunity. The aim of this preliminary study was to characterize, through use of specific antibodies: Toll-like receptor 2, S100, serotonin (5-HT), and Vesicular acetylcholine transporter VAChT, a specific DC-like subpopulation in Pn. schlosseri's epidermis.

The effectiveness of fish feeding behaviour in mirroring trawling-induced patterns.

The ability to observe and predict trawling-induced patterns at spatial and temporal scales that are relevant to inform realistic management strategies is a challenge which scientists have consistently faced in recent decades. Here, we use fish feeding behaviour, a biological trait easily impaired by trawling disturbance, to depict alterations in fish condition (i.e. individual fitness) and feeding opportunities. The benthivorous fish Mullus barbatus barbatus was selected as a model species. The observed trends of responses to trawling in prey species confirmed the effectiveness of a non-trawled zone in sustaining higher levels of diet diversity (e.g. quantity and quality of ingested prey) and fish condition values (e.g. morphometric and physiological Condition Index). Changes observed in fish prey selection confirmed the role of trawling disturbance in modifying the local soft bottoms community, producing alterations of prey availability that trigger shifts in fish diet. Trawling-induced feeding patterns, mirrored through stomach contents, can positively or negatively affect fish condition, the main driver of population dynamics in maintaining carrying capacity levels. Due to the widespread socio-economic value of the red mullet fishery, and the current exploitation status, evidence gathered by the proposed bottom-up trait based approach might inform future trawling adaptation strategies, and tailor spatial conservation measures supporting an Ecosystem-Based Fisheries Management.

Diversity and antibacterial activity of the bacterial communities associated with two Mediterranean sea pens, Pennatula phosphorea and Pteroeides spinosum (Anthozoa: Octocorallia).

A description of the bacterial communities associated with the Mediterranean pennatulids (sea pens) Pennatula phosphorea and Pteroeides spinosum from the Straits of Messina (Italy) is reported. The automated ribosomal intergenic spacer analysis showed a marked difference between coral (tissues and mucus) and non-coral (underlying sediment and surrounding water) habitats. The diversity of the coral-associated communities was more deeply analysed by sequencing the 16S rRNA genes of bacterial clones. P. phosphorea and P. spinosum harbour distinct bacterial communities, indicating the occurrence of species-specific coral-associated bacteria. In addition, only few phylotypes were shared between mucus and tissues of the same pennatulid species, suggesting that there might be a sort of microhabitat partitioning between the associated microbial communities. The predominance of Alphaproteobacteria was observed for the communities associated with both tissues and mucus of P. phosphorea (84 and 58.2 % of total sequences, respectively). Conversely, the bacterial community in the mucus layer of P. spinosum was dominated by Alphaproteobacteria (74.2 %) as opposed to the tissue library that was dominated by the Gammaproteobacteria and Mollicutes (40.6 and 35.4 %, respectively). The antibacterial activity of 78 bacterial isolates against indicator organisms was assayed. Active isolates (15.4 %), which predominantly affiliated to Vibrio spp., were mainly obtained from coral mucus. Results from the present study enlarge our knowledge on the composition and antibacterial activity of coral-associated bacterial communities.

Scanning electron microscopy of the carapace of some Mediterranean crab species.

Observation by SEM of the carapace microstructure of crabs showed, in the past, numerous differences at a specific level (i.e. in the genus Ebalia and Liocarcinus) as described by Spanò et al. (1995, 1999). The aim of this study is to describe the carapace micromorphology of some crab species of very different genera and species. A critical analysis of ecological data and morphological parameters is carried out in order to determine if the differences have adaptive significance.