Calibration of Community-based Coral Reef Monitoring Protocols: Tanzanian Case Study

Coral reef monitoring (CRM) has been recognised as an important management tool and has consequently been incorporated in Integrated Coastal Area Management (ICAM) programmes in the Western Indian Ocean (WIO). Community-based coral reef monitoring (CB-CRM), which uses simplified procedures suitable for local conditions, was introduced in Tanzania in 1996. Despite its widespread use, the method has not been calibrated and the validity of merging CB-CRM results with those gained using other techniques has not been determined. In this study, CB-CRM protocols adopted by the Tanga Coastal Zone Conservation and Development Programme (TCZCDP) were tested against SCUBA-based coral reef monitoring (SB-CRM) as practiced by the Institute of Marine Sciences, University of Dar es Salaam. Calibration showed no significant differences in measuring percent cover of live hard corals, sponges, dead corals and substrata (non-biotic cover). However, CB-CRM monitors recorded higher soft coral and lower fleshy algal cover. Larger differences were observed in deeper (>6 m) transects. Counts of sea cucumbers, clams, gastropods and bivalves categories were not significantly different. However, CB-CRM underestimated the abundance of sea urchins, starfish and younger macro-invertebrates in crevices or under overhangs. There were no differences in the identification of reef fish categories but CB-CRM recorded slightly higher reef fish densities than SB-CRM. If properly trained, CB-CRM monitors can generate results that are comparable to those obtained from SB-CRM on shallow reefs. Although a powerful tool which engenders community involvement and a sense of ownership in the sustainable use of coastal resources, CB-CRM has limitations of which managers need to be aware.