Diel pattern of plasma T 3 and T 4 levels in Baltic salmon parr ( Salmo salar L.) during two seasons
In March (sunrise at 0530, sunset at 1800, water temperature 0.04 °C, and the fish not feeding) plasma T 3 showed no diel variation and plasma T 4 varied only slightly. In May (sunrise at 0200, sunset at 2120, water temperature 9.0 °C, and the fish feeding) plasma T 4 showed a pronounced diel variat...
| Published in: | Canadian Journal of Zoology |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Canadian Science Publishing
1984
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1139/z84-095 http://www.nrcresearchpress.com/doi/pdf/10.1139/z84-095 |
| Summary: | In March (sunrise at 0530, sunset at 1800, water temperature 0.04 °C, and the fish not feeding) plasma T 3 showed no diel variation and plasma T 4 varied only slightly. In May (sunrise at 0200, sunset at 2120, water temperature 9.0 °C, and the fish feeding) plasma T 4 showed a pronounced diel variation with its peak value appearing just before sunset and its nadir occurring at 0800. The plasma T 3 level varied slightly with its peak value at 0400. The constant or slightly varying diel levels of plasma T 3 suggests an efficient regulatory mechanism that maintains the plasma T 3 concentration relatively stable throughout the 24 h. It is concluded that the diel patterns of T 4 and T 3 are dependent on factors related to the season. The influence of photoperiod and feeding on the diel pattern of T 4 is discussed. |
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