Evaluating the validity of a simple citizen science index for assessing the ecological status of urban drainage ponds

Citizen science approaches are valuable tools for biodiversity management and conservation, particularly in urban areas. The OPAL Water Survey is a citizen science approach to assessing water quality by recording the presence/absence of 13 easily identifiable freshwater invertebrate groups. The survey generates a score (the Pond Health Score) that can usefully inform urban freshwater wildlife conservation, as well as engaging urban residents with nature. The main aim of this study was to investigate the capability of the OPAL Pond Health Score to assess the overall ecological status of urban drainage ponds. We applied linear regression between the OPAL Score from 78 drainage ponds across Scotland and a measure of ecological status obtained by the dimension reduction (Principal Coordinate Analysis) of five widely-used ecological indicators: taxonomic richness of amphibians, macroinvertebrates and macrophytes, and adjacent terrestrial habitat richness and degree of urbanization. The OPAL Pond Health Score was strongly correlated with ponds' ecological status established using the five ecological indicators (Pearson's r = 0.86, P < 0.0001). Furthermore, this relationship was generally consistent, both across the entire range of OPAL Scores, and in relation to the different invertebrate groups involved. Thus, the OPAL Pond Health Score has great value as a quick stand-alone assessment method, and offers clear opportunities for collaboration between citizen scientists, government agencies and professional researchers.