Figure 1.

Each meta-ecosystem was composed of two ecosystems with contrasting protist communities: one heterotrophic (white background) and one autotrophic community (green background). The two microcosms within each meta-ecosystem were either linked by diffusion alone (movement of the brown compartment; brown line), or diffusion and dispersal (movement of the blue compartment; blue line). The diffusion of detritus was generated by a gradient of perturbation intensity (0, 5, 30, 80%) and occurred by reciprocal transfer of medium without living organisms. With four replicates per treatment combination, the experiment was composed of 24 meta-ecosystems and four unconnected pairs as controls for a total of 56 microcosms. P, protist community; B, bacteria community; D, detritus; R, resource. (Online version in colour.)