A modified coralligenous bioconstructions quality index (CBQI) to improve the assessment of the ecological status of coralligenous cliffs through the STAR protocol

CBQI is an index developed to assess the quality status of different types of coralligenous habitats (cliffs and banks) on a large scale using photographic images obtained from ROV footage. This study aims to propose the use of the CBQI index to assess the ecological quality of coralligenous cliffs on a small scale, through a modified protocol involving sampling by SCUBA divers. Twelve sites were sampled in the north-western Mediterranean Sea using the STAR standardized method specifically developed for monitoring coralligenous cliffs by SCUBA diving and the CBQI implemented together with STAR indices (ESCA and COARSE). The results of the study showed that the new CBQI sampling protocol, applied by SCUBA divers on coralligenous cliffs, is effective in detecting differences among localities, coherently to STAR indices. The CBQI adds to STAR indices important information on the impact of fishing activity. Therefore, the complementary use of ESCA, COARSE, and CBQI allowed for a more refined assessment of the ecological quality of coralligenous cliffs, as each index provides different and complementary information about the effects of environmental alterations on this type of coralligenous habitat. • CBQI index assess the ecological quality of coralligenous cliffs on a small scale. • a modified CBQI protocol involving sampling by SCUBA divers was proposed. • CBQI was implemented together with STAR indices (ESCA and COARSE). • the new protocol detects differences between unprotected and protected sites. • CBQI adds to STAR indices important information on the impact of fishing activity. • each index offers distinct and complementary insights into environmental alteration.