Do I understand your question correct: you want to know if the season changes circadian clock gene expression even under 12 hours light 12 hours dark (=24 hour) period? In other words: is season perceived despite LD12/12?
I want to know is there any significant changes of circadian rhythm of clock gene expression on fish pineal on different seasons even under 12L-12D, shortday. longday, LL and also DD condition at 24 h time period.
i agree with your opinion, but if water temperature is fixed (i.e. 25 o C) under both season. Then how much significant changes observed on the clock gene expression of fish pineal under summer and winter season?