Evidence for permanent population differences in the annual cycle of plasma "antifreeze" levels of winter flounder

• Published in: Canadian Journal of Zoology
• Main Authors: Fletcher, G. L., Smith, J. C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1980
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Newfoundland
• Online Access: http://dx.doi.org/10.1139/z80-070; http://www.nrcresearchpress.com/doi/pdf/10.1139/z80-070

Seasonal changes in plasma freezing point depression and Cl − concentration in a population of Nova Scotian winter flounder were compared with the seasonal changes which occurred in a population of Newfoundland flounder. The plasma protein "antifreeze" component of the freezing point depression was computed by subtracting the freezing point depression due to the concentration of plasma electrolytes from the total plasma freezing point depression.In Nova Scotian flounder the plasma "antifreeze" level increased approximately 1 month later and declined 2 months earlier than it did in Newfoundland flounder. These differences between the two populations of fish correlated with the regional differences in seawater temperature.When Nova Scotian flounder were transferred to Newfoundland and maintained under Newfoundland conditions of water temperature and photoperiod they retained their plasma "antifreeze" cycle for the duration of the study (approximately 1 year).These results suggest that the timing of the annual plasma "antifreeze" cycle may be a permanent feature of the flounder's physiology and that water temperature does not directly control it. It is hypothesized that some aspects of the annual antifreeze cycle may be endogenous and that if photoperiod plays a role in its regulation the differences between Newfoundland and Nova Scotia are too slight for the cycle to be adjusted in 1 year.