The stress and metabolic responses of Atlantic cod Gadus morhua, L. to acute thermal challenge

From National Research Council Canada

DOIResolve DOI: https://doi.org/10.1111/j.1095-8649.2007.01763.x
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Name affiliation
  1. National Research Council of Canada. NRC Institute for Marine Biosciences
FormatText, Article
Journal titleJournal of Fish Biology
Volume72
Issue4
Pages899–916
Subjectstress; metabolic responses; Atlantic cod; Gadus morhua, L.; acute thermal stress
Abstract
Survival, oxygen consumption (inline image), total plasma cortisol and glucose levels and gill heat-shock protein 70 (hsp70) expression were measured in 10 and 50 g juvenile Atlantic cod Gadus morhua during an acute temperature increase (2° C h−1) to their critical thermal maximum. Ninety three per cent of the fish in both size classes survived to 24° C; however, mortality was 100% within 15 min of reaching this temperature. The inline image for both size classes increased significantly with temperature, reaching peak values at 22° C that were c. 2·8-fold those of control (10° C) fish. Resting plasma cortisol and glucose levels were lower in 10 g as compared to 50 g fish. Plasma glucose levels were highly variable in both size classes, and significant increases were only seen at >22° C for the 10 g fish. In contrast, plasma cortisol showed an exponential increase with temperature starting at 16° C in both size classes, and reached maximum levels at 22° C that were 19-fold (10 g fish) and 35-fold (50 g fish) higher than their respective control groups. Both the constitutive (73 kDa) and inducible (72 kDa) isoforms of hsp70 were detected in both size classes using the widely utilized mouse monoclonal antibody. Expression of these isoforms, however, did not change when Atlantic cod were exposed to elevated temperature, and the 72 kDa isoform was not detected using salmonid-specific antibodies. These results indicate that juvenile Atlantic cod are very sensitive to acute increases in water temperature. In addition, they (1) show that inline image and plasma cortisol, but not plasma glucose or gill hsp 70 levels, are sensitive indicators of thermal stress in Atlantic cod and (2) support previous reports that the upper critical temperature for this species is 16° C.
Publication date
PublisherWiley
LanguageEnglish
Peer reviewedYes
NRC numberNRCC 42722
1272
NPARC number3538235
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