Comparative Diplectanum aequans (Monogenea) infestations in cultured European seabass (Dicentrarchus labrax) in the Black Sea and the Aegean Sea

In the present study, monogenean infestations were investigated on the gills of the European seabass Dicentrarchus labrax grown in culture cages located at Yakakent coast of the Black Sea and Milas coast of the Aegean Sea. Parasitological investigations were conducted simultaneously at both localities during September 2014, February and April 2015. While a total of 100 fish specimens were examined from Yakakent samples whose average length was 19.37 cm, a total of 88 fish specimens were examined from Milas samples whose length was 22.67 cm in average. Only one monogenean species Diplectanum aequans was recovered from investigated fish specimens at both sampling localities. Infestation prevalence (%) and mean intensity values of D. aequans were 89.0% and 9.6 ± 0.8 in Yakakent samples while those infestation indices were 90.9% and 13.3 ± 1.2 in Milas samples, respectively. The difference between the infestation prevalence (%) values of D. aequans at both sampling localities was not statistically significant, on the other hand, the difference was statistically significant in the mean intensity values at both locations. Diplectanum aequans showed a homogeneous distribution in all gill arches of fish without any statistically significant difference. This is the first comparative study on the infestation of D. aequans on the gills of European sea bass D. labrax cultured in the Black Sea and the Aegean Sea