7.4.3 The question
Here we discuss two central questions addressed by the model. First, how do the proportion and spatial patchiness of obstacles in a stream reach affect the mean distance travelled by drifting animals? We fixed the proportion of obstacles at either 5% or 15%, and at each of these proportions we varied the size (mean ± SD) of individual DWZs from 2 ± 1 to 6± 1 square cells (Figure 7.4). We hypothesized that both of these factors