UVB Radiation Variably Affects n‐3 Fatty Acids but Elevated Temperature Reduces n‐3 Fatty Acids in Juvenile Atlantic Salmon (Salmo salar)

Abstract

Temperature and ultraviolet B radiation (UVB 290–320 nm) are inextricably linked to global climate change. These two variables may act separately, additively, or synergistically on specific aspects of fish biochemistry. We raised Atlantic Salmon (Salmo salar) parr for 54 days in outdoor tanks held at 12 and 19 °C and, at each temperature, we exposed them to three spectral treatments differing in UV radiation intensity. We quantified individual fatty acid (FA) mass fractions in four tissues (dorsal muscle, dorsal and ventral skin, and ocular tissue) at each temperature × UV combination. FA composition of dorsal muscle and dorsal and ventral skin was not affected by UV exposure. Mass fractions of 16:0, 18:0, and saturated fatty acids (SFA) were greater in dorsal muscle of warm‐reared fish whereas 18:3n‐3, 20:2, 20:4n‐6, 22:5n‐3, 22:6n‐3, n‐3, n‐6, polyunsaturated fatty acids (PUFA), and total FA were significantly higher in cold‐reared fish. Mass fractions of most of the FA were greater in the dorsal and ventral skin of warm‐reared fish. Cold‐reared salmon exposed to enhanced UVB had higher ocular tissue mass fractions of 20:2, 20:4n‐6, 22:6n‐3, n‐3, n‐6, and PUFA compared to fish in which UV had been removed. These observations forecast a host of ensuing physiological and ecological responses of juvenile Atlantic Salmon to increasing temperatures and UVB levels in native streams and rivers where they mature before smolting and returning to the sea.

Diet, size and location as determinants of n-3 long-chain polyunsaturated fatty acid content in farmed Atlantic Salmon (Salmo salar )

“…Although temperature is known to influence Atlantic Salmon PUFA uptake and retention in experimental studies (Arts et al . ), often in a diet‐dependent manner (Jobling & Bendiksen ), the large variability in n‐3 LC‐PUFA levels within and among salmon feeds observed in the present study (Fig. b) likely precluded the detection of any subtle effects on salmon flesh quality arising from environmental differences (e.g.…”

“…Arts et al . ), suggests that the acquisition of sufficient n‐3 LC‐PUFA early in life could significantly affect maximum n‐3 LC‐PUFA accumulation later in life, which could reconcile these apparently conflicting findings.…”

“…) influence fish nutrient requirements. It has also been suggested that dietary and environmental conditions experienced by juvenile salmon could influence resultant n‐3 LC‐PUFA levels of older fish at harvest size (Arts, Palmer, Skiftesvik, Jokinen & Browman ) and that the influence of temperature on fish n‐3 LC‐PUFA content depends on dietary PUFA sources (Olsen & Henderson ; Bendiksen et al . ).…”

“…In addition, both temperature and salmon size (Torstensen et al 2005) influence fish nutrient requirements. It has also been suggested that dietary and environmental conditions experienced by juvenile salmon could influence resultant n-3 LC-PUFA levels of older fish at harvest size (Arts, Palmer, Skiftesvik, Jokinen & Browman 2012) and that the influence of temperature on fish n-3 LC-PUFA content depends on dietary PUFA sources (Olsen & Henderson 1997;Bendiksen et al 2003). Thus, the dietary uptake and flesh deposition of n-3 LC-PUFA by farmed Atlantic Salmon depends on the independent as well as the interactive effects of diet, temperature and fish size Torstensen et al 2005;Bendiksen, Johnsen, Olsen & Jobling 2011;Bowyer, Qin & Stone 2013).…”

Reproductive life-history strategies in lake whitefish (Coregonus clupeaformis) from the Laurentian Great Lakes

“…Total lipid (dry mass basis) and a standard suite of 37 fatty acid methyl esters (g FAME·mg dry mass −1 ) of females and their eggs were analyzed in three steps: gravimetric extraction, derivitization, and quantification on a gas chromatograph. The specific methods used for total lipid and FA analyses are given by Zellmer et al (2004) and Arts et al (2012), respectively.…”