Inducible heat tolerance in Antarctic notothenioid fishes

Significant increases in heat tolerance (time of survival at 14 degrees C) were observed for some, but not all, species of notothenioid fishes collected from McMurdo Sound, Antarctica (77 degrees 51'S) following acclimation to 4 degrees C. The increase in thermal tolerance was rapid in Trematomus bernacchii, developing within 1-2 days of acclimation to 4 degrees C. Long-term (6-8 weeks) acclimation to 4 degrees C led to greater heat tolerance in Trematomus pennellii than in T. bernacchii. Unlike its demersal congeners, the cryopelagic notothenioid Pagothenia borchgrevinki did not increase heat tolerance during warm acclimation. A deep-living zoarcid fish, Lycodichthys dearborni, also failed to increase heat tolerance, but survived significantly (> threefold) longer at 14 degrees C than the notothenioids.