Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: December 13, 2005
Publication Date: February 3, 2006
Citation: Welker, T.L., Mcnulty, S.T., Klesius, P.H. 2006. Effect of hypoxia stress on blood glucose, plasma cortisol, and susceptibility to Edwardsiella ictaluri in channel catfish (Ictalurus punctatus Rafinesque). Aquaculture America Conference. Las Vegas. NV. p. 166. Technical Abstract: The effect of sublethal hypoxia exposure on plasma cortisol, blood glucose, and susceptibility to Edwardsiella ictaluri infection in juvenile channel catfish (Ictalurus punctatus Rafinesque) was determined. Fish were monitored for temporal changes in cortisol and glucose concentrations before, during, and after 2 h exposure to <2 mg L-1 dissolved oxygen (DO) and while maintained under normoxic conditions (~6.0 mg DO L-1) (Figure 1). Plasma cortisol increased significantly (P<0.001) in response to hypoxic conditions (Figure 2). Fish exposed to hypoxic or normoxic conditions were challenged with a high dose (1.3 x 107 CFU mL-1) or low dose (1.3 x 105 CFU mL-1) of E. ictaluri or sterile culture broth by 30 min immersion bath. One percent of fish in both the normoxic and hypoxic groups died when challenged with the E. ictaluri low dose (Table 1). However, when challenged with the high dose of E. ictaluri, catfish exposed to hypoxic conditions had significantly higher (P=0.02) cumulative mortality (36%) than fish maintained under normoxic conditions (12%). Increased susceptibility of channel catfish to E. ictaluri appears to be the result of the immunosuppressive effects of the stress response to hypoxia.