Ergasilid copepod infestation on some widely consumed fish species in Valaichchenai Lagoon, Batticaloa District, Sri Lanka

The present study was undertaken to find out the ergasilid copepod infestation on widely consumed fish species along three different locations in Valaichchenai lagoon during the Northeast monsoonal period from November 2019 to February 2020. The ergasilid copepod species namely Dermoergasilus amplectens, Ergasilus sieboldi, Ergasilus parvitergum and Sinergasilus major were recorded in the widely consumed fish species such as Etroplus suratensis, Mugil cephalus and Leiognathus fasciatus of Valaichchenai lagoon. The results revealed the prevalence and mean intensity in different gender of fish species for each ergasilid parasite in each location of the lagoon. Ergasilus parvitergum showed the maximum prevalence of 28.57%, 53.33% and 26.67% in each sampling locations of L1, L2 and L3 respectively. The highest mean intensity (14.5) was recorded in sampling location L1 for Ergasilus parvitergum which indicated that E. parvitergum is more adapted to their fish hosts when compared to other ergasilid copepod parasites found in Valaichchenai lagoon. Invasion of Sinergasilus major was recorded at polyhaline water (L1) in the present study. Spatial variation exists in the parasitic prevalence of Sinergasilus major (P = 0.00) and E. parvitergum (P=0.044) between sampling locations of the lagoon. However, spatial variations do not exist the in parasitic prevalence of Ergasilus sieboldi (P=0.124) and Dermoergasilus amplectens (P=0.749) between the sampling locations of the lagoon. Furthermore, the overall prevalence of parasites in the host fish values were 66.67% and 33.77% in females and males respectively which shows significant differences to each other. From the present study, it can be inferred that gender influences the degree of ergasilid parasitic infestation in fish during the northeast monsoonal period.