Effects of Diet and Ultraviolet Radiation on the Predator-Prey Behavior and Metabolic Rates of the Juvenile Reef Fish Patagonotothen Sp

VALIÑAS, M.S.; HELBLING, E.W.

Córdoba

Congreso; 16th International Congress on Photobiology; 2014

International Union of Photobiology- Universidad Nacional de Mar del Plata

The deleterious effects of ultraviolet radiation (UVR) on survival of aquatic organisms have been documented for a wide range of taxa and ecosystems [1,2]. However, UVR affects factors other than mortality, and many studies have demonstrated subtle responses to UVR [2]. UV-absorbing compounds (UVAC) are the most common UV-sunscreens synthetised by primary producers [3,4], and it had been demonstrated that several aquatic organisms can counteract the detrimental effects of UVR by consuming food rich in these compounds [5,6]. In this study we investigated the combined effect of UVR and diet on predator-prey behavior (prey capture time; PCT) and metabolic rates (respiratory frequency; RF) of juveniles of the marine reef fish Patagonotothen sp. collected from Patagonian rocky Shores. Fish were exposed to two radiation treatments: PAB (>280 nm) and P (>400 nm), and fed, 3 days before to the beginning of the experiment and until its end (12 days after), with two diets: a) poor in UVAC (amphipods fed with Ulva rigida), and b) rich in UVAC (amphipods fed with Porphyra columbina). The PCT (time in seconds since the prey was thrown to the chamber until the fish caught them) was affected by UVR but not by diet. Independently of the diet, under UVR, fish took more time to capture their prey than those not exposed to UVR. This seems to indicate that fish did not obtain benefits from UV absorbing compounds. The RF (number of operculum movements per minute) was significantly affected both by UVR and diet. Higher RF was observed in individuals exposed to UVR and fed with the poor-UVAC diet. The higher RF under UVR could reflect energetic costs related to the repair of cellular components damaged by UVR, which could reduce energetic reserves necessary for the growth of this fish species, especially during periods of high UVR levels.