The “Quality of Rocky Bottoms” index (CFR by its Spanish acronym) is a multimetric method used for the assessment of macroalgae communities in intertidal and subtidal areas.

It was developed according to the basic requirements of the European Water Framework Directive (WFD; 2000/60/EC) in order to carry out general management and monitoring works.

The method is based on a community approach which avoids exhaustive taxonomical identifications, thus allowing its easy and fast application over extensive coastal areas.

The CFR index has been successfully intercalibrated for the Northeast Atlantic region and therefore validated by the European Commission for its use in the implementation of the WFD (Commission Decision 2013/480/EU).

At the National level, the index has been accepted by the Spanish Government for the assessment of macroalgae in the Atlantic coasts (BOE 2013a; BOE 2013b).