Chapter Effects of Abiotic (Salinity) and Biotic (Ectoparasite) Stressors on Coris julis (Linnaeus, 1758) in Ibiza, Balearic Islands: A Biomarker Analysis

Abstract

Stressful situations include abiotic factors such as exposure to hypersaline waters derived from desalination plants and biotic factors such as infection by new parasites introduced by human activities. The aim was to study the effects of an abiotic factor (salinity) and a biotic factor (ectoparasite) on the small coastal wrasse Coris julis (Linnaeus, 1758). Specimens were obtained in three areas of the Island of Ibiza (Balearic Islands): control area, area influenced by the desalination plant and area with high levels of parasite infection. Biomarkers of oxidative stress in the gills, liver and epithelial mucus were analysed, as well as immunological markers in the mucus. The two stress factors induced a differential response, with a greater effect of salinity on the gills and a greater effect of the parasite on the liver and mucus. Innate immunity increased in the mucus of fish under both stressors, and immunoglobulin levels increased only in the presence of parasite. In conclusion, C. julis specimens affected by salinity and an ectoparasite respond with an increase in antioxidant and immunological defence mechanisms.