Fig. 3. Conductivity data representing the number of stimulus peaks detected per second (open circles) and the relative peak concentrations (closed circles) for (A) the three fastest unobstructed flows and (B) the three flow treatments having a free-stream velocity of 5 cm s^–1. Values for the smooth condition (U=5 cm s^–1) are included in both graphs for the sake of comparison. Data points represent an average of three replicates (±S.E.M.) in which conductivity was recorded for 30 s at a frequency of 10 Hz. Peaks were identified as bursts of concentration above a baseline that was established from background measurements collected prior to each trial. Peak concentrations (C) include all measurements that exceeded baseline and are normalized to source concentration (C₀).