Reef

In the strict sense of the term, a reef is a constructed structure of organic origin, normally in shallow water, whose constituents build a rigid frame capable of resisting the action of the waves and currents. In the broad sense of the term, a reef is an organic structure. The Belgian Frasnian “reefs” are constructions whose deepest part was under the area of the waves.

In general, several phases can be distinguished in the construction of such structures. First of all, there is a stabilisation phase: a certain number of species fix the substrate. This is then colonised by other species that have a constructive action (colonisation phase). Then comes the diversification phase: the number of species increases significantly. The majority of structures are formed during this phase. The domination of certain species – only a limited number – constitutes the final phase.