Ultraviolet vision and foraging in juvenile bluegill (Lepomis macrochirus)

Abstract

Ultraviolet (UV) photoreceptors have been reported in a wide variety of freshwater and marine organisms, suggesting that UV vision is prominent in aquatic ecosystems. However, its adaptive significance remains speculative. The present study tested whether the foraging of juvenile bluegill (Lepomis macrochirus) is enhanced in the presence of UV radiation (UVR). Laboratory feeding trials were conducted in a laminar flow tank in which L. macrochirus juveniles between 2.3 and 3.5 cm standard length were fed the cladoceran Daphnia magna. Sighting and striking distances, as well as capture success, were measured in the presence and absence of UVR. Mean sighting and striking distances and capture success did not differ significantly between the two light treatments. There were also no significant differences in the frequency distributions of sighting and striking distance. These results suggest that UV vision may not be used to enhance foraging in L. macrochirus on Daphnia within the size class tested.