The Impact of Turbidity on Sunfish Foraging Efficiencies
Jon DeCoste '05, Doug Morin '07, Jorie Pollak '04 and Conor Taff '05

Turbidity is a measure of water clarity, and increased turbidity due to accelerated algal growth and erosion is a widespread environmental issue. As waters become more turbid, water clarity decreases, and the visual environment for aquatic organisms is altered. While most studies of turbidity have focused on the turbidity thresholds that result in the death of various aquatic organisms, community interactions are most likely altered at lower turbidity levels. We conducted a series of experiments to evaluate the impact of various turbidity levels on juvenile bluegill sunfish foraging efficiencies. We found that foraging efficiencies are highest at intermediate turbidity levels (e.g., 10-20 NTUs), and drop significantly at low (3.5-6 NTUs) and high turbidity levels (22-25 NTUs). We hypothesize that the decrease in foraging efficiencies in clearer water is due to predator avoidance, while the decrease in foraging efficiencies at higher turbidity levels is due to the poor visual environment.

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