Influence of Turbidity on the Foraging of Largemouth Bass

Water turbidity has the capacity to influence fish foraging success and behavior. The largemouth bass Micropterus salmoides is a popular sport fish in the southeastern United States that is primarily a visual predator. The high turbidity in many systems can be attributed to sediment loading from agricultural lands, and it can reduce the availability of light in the water column and have direct impacts on largemouth bass foraging success. We investigated the effect of different turbidity levels (0, 10, 25, 50, 100, and 250 nephelometric turbidity units [NTU]) on largemouth bass foraging in aquaria by testing the hypothesis that turbidity has no effect on the time required to locate tethered prey (fathead minnow Pimephales promelas and golden shiner Notemigonus crysoleucas) or ultimate capture success. The percentages of prey captured that were derived from aggregated data in multiple trials at the different treatment levels differed significantly. One-hundred percent of the largemouth bass in the 0-NTU treatments captured the prey. Conversely, only 15% of the largemouth bass in the 250-NTU treatments captured the prey throughout all trials. The average time taken to capture the prey also was significantly different between treatment combinations, with time to interaction increasing as turbidity increased. The results from this study suggest that greater turbidity levels reduce the ability of largemouth bass to capture prey and increase the time taken to locate and interact with prey. Thus, turbidity may impact individual fitness and management strategies.