The use of Risk Incidence and Diversity Indices to evaluate water quality of semi-arid reservoirs

Local ecological knowledge of water quality indicators can be an important element in the management and conservation of aquatic ecosystems from a biocultural conservation perspective. We investigated the ecological indicators of water quality used by local communities that live around reservoirs in the semi-arid region of Brazil to compare their Risk Incidence Indices with their Diversity Indices. This research was undertaken at four reservoirs, and interviewed 126 members of human communities, using a semi-structured format. The macrobenthic fauna was sampled at 332 sites within the reservoirs for the bio-indicator analyses. Among the ecological indicators of water quality cited by the interviewees, the most notable were water color and odor. When the Risk Incidence Index was high, the Biodiversity Index was found to be low. Larger proportions of Oligochaete occurred in reservoirs with low biological diversity, indicating that local ecological knowledge reflected reservoir water quality. Our studies showed that local ecological knowledge of water quality indicators, in conjunction with traditional indicators such as the macrobenthic fauna, can be used for biocultural conservation purposes.