Table 1 Colonization ratios based on the number of individuals/m^{2} and based on taxa.Colonization ratio for number of individuals was calculated as the number of individuals/m^{2} found in trays retrieved after 3 months divided by the number of individuals/m^{2} found in the donor system at the start of the experiment. For taxa, this was performed similarly, i.e., the number of taxa in trays after 3 months divided by the number of taxa at start. Means ± SD correspond to *n* = 4, except for 0.05 and 0.5% (3 months), where *n* = 3; and transects, where *n* = 2.