A critical assessment of data derived from coral cay conservation volunteers

Since 1986, Coral Cay Conservation (CCC) has utilized a workforce of over 900 specially-trained volunteer divers to collect detailed topographic, bathymetric and biological data for the establishment of management plans for selected areas of the Belize barrier reef. The biological data recorded are ordinal and reflect the abundance of reef organisms including fish, macroalgae and hermatypic corals on a scale of 0-5. Substrate composition and the coverage of principal biotic classes are also visually assessed using an ordinal scale of 0-5. An exercise was carried out to assess the accuracy and consistency of data recorded by volunteers. Transects were laid in each of the major reef zones and in lagoon habitats. Each transect was surveyed independently by six teams of trained volunteers and compared to a reference obtained by experienced CCC staff. Analyses were carried out to test the accuracy and consistency of the coral, macroalgal and habitat data. Further analyses sought to quantify the proportion of species correctly identified, the frequency of erroneous species recordings and the variation of abundance ratings. The overall accuracy of coral surveys varied from 52-70% with the poorer values obtained in deeper outer and inner drop-off reef zones. The trend of reduced surveyor performance in deeper water is discussed in terms of physical, physiological and psychological phenomena. Inter-group consistency exhibited a similar bathymetric trend to that found for coral accuracy. Macroalgae were generally accurately and consistently recorded. No clear trend of improved accuracy and consistency following greater survey experience was apparent. Substrate composition and biological cover were recorded with an accuracy exceeding 90% in seagrass habitats and 70-90% in reef sites. A number of recommendations are made to improve survey methodology and volunteer training