Chapter Fish immune and oxidative stress reaction to emerging parasite in the balearic islands

Abstract

Global change has a deep impact on the distribution and prevalence of diseases in fish, leading to the emergence of new pathogens. A recent observation on Ibiza Island in the Balearic Islands highlighted the presence of black spot disease linked to a digenean fluke belonging to the genus Scaphanocephalus in Xyrichthys novacula specimens. The study aimed at assessing the antioxidant and immune responses in mucus and spleen of X. novacula, that are infected by Scaphanocephalus sp. Two sites were selected, one devoid of the parasite and other with its presence. Fish were divided by severity of infection (low or high). Weight and size were measured, and mucus and spleen samples were obtained. As the infection was increased, the body index was worst and antioxidant enzymes activities and immunological parameters in mucus increased. However, the systems could not prevent lipid peroxidation. Also increases in immunological determinations were observed in the spleen. In conclusion, Scaphanocephalus sp. in X. novacula triggers an immune response and oxidative stress in the mucus as the infection is more severe. These changes are accompanied by a decrease in their body condition.