COMPARATIVE STUDIES ON THE METABOLISM OF SHALLOW-WATER AND DEEP-SEA MARINE FISHES .5. EFFECTS OF TEMPERATURE AND HYDROSTATIC-PRESSURE ON OXYGEN-CONSUMPTION IN THE MESOPELAGIC ZOARCID MELANOSTIGMA-PAMMELAS

Measurements were made of routine O2 consumption rates (.ovrhdot.VO2) of the mesopelagic deep-sea zoarcid fish M. pammelas. Determinations were made over ecologically relevant ranges of 3 variables; temperature (3-10.degree. C), hydrostatic pressure (1-170 atm) and O2 partial pressure [PO2] (1-160 mm Hg). Weight-specific .ovrhdot.VO2 were uniformly low. Of the 3 test variables, only temperature had significant metabolic effects within the ranges studied. Q10 was 6.75 between 3-5.degree. C, 1.47 between 5-7.degree. C and 17.4 between 7-10.degree. C. These Q10 were constant over the hydrostatic pressure range studied. Between 3-7.degree. C the fish regulated their rates of O2 consumption down to PO2 comparable to those occurring in their natural environments (6-12 mm Hg). They showed no capacity to tolerate anoxic conditions. The physiological and ecological significance was discussed, particularly with reference to thermal effects and to the basis of survival of this fish in the O2 minimum layers of the eastern Pacific Ocean. Since it is possible to maintain M. pammelas in the laboratory for extended periods of time (over 12 mo.) it could be used for studies of deep-sea fish biology.