Temporal variation (mean ± 1 SD) of macroinvertebrates in (a) total taxonomic richness (number of families), (b) EPT richness (number of EPT families), (c) total density (ind m⁻²), (d) total biomass (mg m⁻²), (e) dominance (ind. dominant taxon/ind. total taxa) and (f) diversity (Margalef's index) sampled in the control (white), one-crayfish (grey) and two-crayfish (black) enclosures. For Graph b, crayfish density treatments that significantly differed from each other are denoted with different lowercase letters over the bars (a, b), and combinations of these letters (ab) indicate a lack of effects in relation to individual groups.