CIRCADIAN AND SEASONAL RHYTHM OF TOTAL ANTIOXIDANT CAPACITY AND REACTIVE OXYGEN AND NITROGEN SPECIES IN ATLANTIC SALMON Salmo salar  

Nicholas C. Fargnoli* and Timothy J. Bowden
 
 School of marine sciences
 University of Maine
 Orono, ME 04469
 Nicholas.Fargnoli@maine.edu

Antioxidants in the serum of higher vertebrate mammals like mice and humans have been shown to fluctuate on a seasonal and circadian basis, but there is no evidence that this occurs in fish species.  Total antioxidant capacity and total reactive oxygen and nitrogen species from liver and serum were studied to assess how they fluctuate on seasonal and circadian cycles.  It was shown that antioxidant content peaked during the month of August and was lowest during the month of May.  Our study also shows that there was no definitive seasonal variation of reactive oxygen and nitrogen species, but fluctuates more on a circadian rhythm with reactive species being highest in the morning and lowest in the late afternoon and night.  For the last 20 years hydrogen peroxide has been one of the methods for controlling sea lice and amoebic gill disease. Understanding of the temporal variations in antioxidant activity may provide of valuable management tool for aquaculture farmers by indicating optimum treatments times, such as specific time of day or season that may allow for better success of the treatment, and thus minimize stress on the animals.