Table 1. The threshold of motion for each caddisfly treatment in the experiment.

Treatment	Crtitical Shear Stress (Pa)	Critical Shields Stress	Proportional increaseabove control
Control	11.0±0.5	0.034	0.00
Ceratopsyche	17.3±1.1	0.053	0.57
Arctopsyche	23.0±1.4	0.071	1.10
Polyculture expected	20.4±0.7	0.063	0.86
Polyculture observed	27.8±1.3	0.086	1.50

The critical shear stress, non-dimensional Shields stress, and proportional increase over the control are given. Critical shears stress values are means ±1 SE. The Shields stress corresponds well to values measured in nature ranging between 0.03–0.08.