Metabolic and behavioral responses of the reef fish Patagonotothen cornucola to ultraviolet radiation: Influence of the diet

• Effects of UVR and diet on juvenile fishes were evaluated.
• UVR acted as a stress factor in fishes by increasing their respiratory frequency.
• UV-absorbing compounds in the diet counteracted the effects of UVR on respiration.
• Fishes exposed to UVR took more time to detect and capture their preys.

Most of the studies devoted to assess the effects of ultraviolet radiation (UVR) on fishes have been done with early life stages (i.e., eggs and larvae) as they are the most vulnerable to these wavelengths; however, the effects of UVR on juveniles or adults are less clear. This study evaluated the effects of UVR and diet (i.e., rich and poor in ultraviolet-absorbing compounds; UVAC) on the metabolic rates (respiratory frequency) and behavior (prey capture time) of juveniles of the reef fish Patagonotothen cornucola, a common species inhabiting the intertidal areas of the Patagonian coast. UVR was a significant stress factor for P. cornucola by increasing its respiratory frequency, which could be related to the costs of repairing any cellular components damaged during the exposure. Fish exposed to UVR took more time to detect and capture their prey, which could lead to a reduction in the prey capture rates, with the concomitant effects on growth. In addition, juveniles feeding on rich-UVAC diet had a significant lower respiratory frequency than those feeding on poor-UVAC diet. This differential response was not evident in the prey capture time. In their natural environment, P. cornucola could feed on a varied diet and could also partially avoid the exposure to UVR by hiding under the rocks or macroalgae. Future studies should consider the broad variety of diets that could be found in rocky intertidal areas, and how their qualities (in terms of UVAC content) could help to counteract the UVR effects on juvenile fish.