Effects of the gill monogenean Zeuxapta seriolae (Meserve, 1938) and treatment with hydrogen peroxide on pathophysiology of kingfish, Seriola lalandi Valenciennes, 1833.
Infections by the gill fluke Zeuxapta seriolae are a serious concern for sea cage aquaculture of kingfish, Seriola lalandi. The present study aimed to determine the pathophysiological effects of a progressive infection with Z. seriolae and the effects of treatment with hydrogen peroxide. For the progression of infection study, infected fish were taken from a sea cage farm, treated to remove parasites and then infected by cohabitation with heavily infected fish. Samples were taken at 2-week intervals for 8 weeks. Infection intensity peaked at 4 weeks post-infection (mean intensity 565.9) and the number of mature worms (2 mm fixed length or larger) peaked at 6 weeks post-infection. Attachment of Z. seriolae appeared to cause little localized pathology; however, the occurrence of hyperplastic lamellae increased as the infection progressed. Haemoglobin concentrations were negatively correlated with Z. seriolae intensity and were lower than controls at 4 weeks (35.8% decrease) and 6 weeks (57.4% decrease) post-infection. Blood lactate concentration and plasma osmolality increased throughout the course of infection. For the effect of treatment experiment, groups of infected and non-infected fish were sampled either before or after treatment with hydrogen peroxide. Treated fish from both infected and uninfected groups had increased plasma lactate, osmolality and pH compared with pre-treatment groups. Treatment with hydrogen peroxide appeared to have acute effects on fish health but the magnitude (e.g. lactate, osmolality) and extent of the effects (e.g. haemoglobin) was much less than that caused by chronic infection with Z. seriolae.
Mansell
B
B
Tasmanian Aquaculture and Fisheries Institute, School of Aquaculture, University of Tasmania, Launceston, Tasmania, Australia.
Powell
M D
MD
Ernst
I
I
Nowak
B F
BF
D000704:Analysis of Variance; D000818:Animals; D017756:Aquaculture; D005393:Fish Diseases / Q000188:drug therapy* / Q000469:parasitology* / Q000503:physiopathology; D005880:Gills / Q000469:parasitology / Q000473:pathology; D006374:Helminthiasis, Animal / Q000188:drug therapy / Q000503:physiopathology*; D006454:Hemoglobins / Q000378:metabolism; D006652:Histological Techniques / Q000662:veterinary; D006861:Hydrogen Peroxide / Q000627:therapeutic use*; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000097:blood; D009994:Osmolar Concentration; D010473:Perciformes; D010986:Platyhelminths
D006454:Hemoglobins; D019344:Lactic Acid; D006861:Hydrogen Peroxide