Diplectanum sciaenae (Van Beneden & Hesse, 1863) (Monogenea) infecting meagre, Argyrosomus regius (Asso, 1801) broodstock in Catalonia, Spain. A case report

Recurrent infection of captive meagre, Argyrosomus regius, by a monogenean parasite has been observed in the broodstock facilities of Institut de Recerca i Tecnologia Agroalimentàries (IRTA) in Catalonia, Spain, between 2008 and 2015. Following handling procedures related with hormonal treatment for spawning induction, one fish died. Post-mortem examination and detailed microscopical examination using light microscopy, SEM, and histology revealed intense infection by Diplectanum sciaenae (Monogenea, Diplectanidae) which caused noteworthy gill pathology. In the present study, we provide detailed description of the parasite and the pathology caused to its host. This is the first report associating this parasite with disease and mortality in farmed meagre.

Ontogenesis of the HPI axis and molecular regulation of the cortisol stress response during early development in Dicentrarchus labrax

The cortisol stress response and the molecular programming of the corticoid axis were characterized for the first time during early ontogeny in a Mediterranean marine teleost, the European sea bass (Dicentrarchus labrax). Sea bass embryos, pre-larvae and larvae at specific points of development were exposed to acute stressors and the temporal patterns of cortisol whole body concentrations and the expression of genes involved in corticosteroid biosynthesis, degradation and signaling were determined. Expression of genes (gr1, gr2, mr, crf) involved into the corticoid response regulation combined with histological data indicated that, although a cortisol stress response is evident for the first time around first feeding, a pattern becomes established in larvae at flexion until the formation of all fins. Moreover, mRNA transcript levels of 11β-hydroxylase and 11β-hsd2 showed a strong correlation with the whole body cortisol concentrations. Concluding, our data reveal the presence of an adaptive mechanism in European sea bass at early ontogeny enabling to cope with external stressful stimuli and provide a better insight into the onset and regulation of the stress response in this species.

Chronic ulcerative dermatopathy in cultured marine fishes. Comparative study in sharpsnout sea bream, Diplodus puntazzo (Walbaum)

Chronic ulcerative dermatopathy (CUD) also known as chronic erosive dermatopathy, hole-in-the-head, head and lateral line erosion syndrome (HLLE) and lateral line depigmentation (LLD) is a chronic disease of unknown aetiology that affects the lateral line canals of the head and the trunk of various fish species. It has been described only in freshwater species although there are reports that it also affects marine fish. Here, we describe the disease in cultured sharpsnout sea bream using histology and scanning electron microscopy and identify several marine species as CUD sensitive. The results of this study correlate the development of the disease with the use of borehole water, indicating that the aetiology is probably associated with water quality rather than nutritional imbalance or infectious agents.