I am marine ecologist working on infralittoral rocky reef in the Mediterranean Sea.

I am studying 'Cystoseira forests', that is an assemblage of macroalgae dominated by Cystoseira species (around 20 ind./m²), a brown algae whose 'branches' form dense canopy from 5cm to 20 cm up to the substrate. Below this canopy, i.e. around the tronks of Cystoseira individuals, some sponges, calcareous algae and other sessile sciaphilic organisms are dwelling. (BTW, I doubt we can call it a shrub strata, since most of them are encrusting organisms, i.e. 'confounded with the substrate')

Within 0 and 5 cm from the substrate, i.e. up the sessile sciaphilic organisms (among the only few non-encrusting organisms) and below the canopy, some small bodied fishes are living there. May I call it understory, considering this microhabitat is less complex than the canopy?

I am studying other macroalgae assemblages (Dictyotales- , Sphacelariales-, articulated Corallinales- dominated assemblages) that don't present a canopy. In these habitat, dominant erect macroalgae are usually