Abstract Preference by juvenile plaice for vegetated or unvegetated substratum was investigated in laboratory experiments to study the impact of recent changes in vegetation structure in shallow nursery areas on the recruitment of plaice. The experiments were done in circular tanks with filtered flow-through sea-water. The tanks were divided into two parts, one with bare sediment and the other with mat-forming benthic microalgae or patches of filamentous macroalgae ( Enteromorpha intestinalis and Rhizoclonium spp.) attached to small cobbles. Substratum preference were tested for different size-classes of juvenile plaice, ranging in size from 11 to 50 mm. Recently metamorphosed (11–15 mm) and post-settlement (16–26 mm) juveniles showed a significant preference for bare sediment compared with areas containing patches of filamentous algae. Post-settlement juveniles (16–26 mm) also exhibited a significant preference for bare sediment compared with sediment covered with mat-forming benthic microalgae. The differences in substratum selection disappeared 6 to 8 weeks after settlement in individuals that were 35 to 50 mm in total length. Field sampling verified that density of plaice (17–34 mm) was significantly lower in vegetation patches than in areas of bare sediment.