Effects of turbidity on foraging of juvenile black and white crappies

Abstract

AbstractTurbidity can fluctuate rapidly during the early life of fishes, impacting foraging behaviours. For piscivores, turbidity may hinder foraging, whereas planktivores and juvenile fishes may increase foraging activity and decrease antipredator behaviours in moderate levels of turbidity. Black crappie (Pomoxis nigromaculatus) and white crappie (P. annularis) population trends are often related to changes in turbidity. Yet effects of turbidity on juvenile foraging of these species are unknown and may differ between species. To evaluate effects of three turbidity levels (0, 25 and 50 NTU) on juvenile crappie foraging, controlled experiments compared (a) consumption and size selection for a single prey and (b) selection, total consumption and energetic value of diets when offered three distinct prey options. Overall, black crappies exhibited universally greater diet biomass than white crappies. Black crappies displayed higher prey consumption and were more size selective of a single‐prey type, whereas white crappies were less size selective and maintained uniform consumption as turbidity increased. Selection patterns for three prey types were similar among species and turbidity levels, with Chaoborus preferred and Chironomus avoided. However, black crappies also avoided Daphnia, whereas white crappies consumed them neutrally. Overall, turbidity did not impair foraging of juvenile crappies. Turbidity‐driven fluctuations in prey base paired with predator interactions likely also contribute to observed growth and abundance fluctuations in natural systems.