Understorey benthic microalgae and their consumers depend on habitat complexity and light in a microtidal coastal ecosystem

- We experimentally tested the role of coastal habitat complexity across trophic levels.
- We manipulated the presence of macroalgal canopy, propagules, light and nutrients.
- Periphyton biomass and richness was strongly reduced by canopy presence and shading.
- Invertebrate density and richness strongly increased with canopy presence.
- Microalgal species richness and biomass decreased with increasing invertebrate richness and density.