Assessing the Robustness of Participatory Science for Tracking Spatio-Temporal Changes in Marine Benthic Biocenoses on Artificial Reefs

Participatory science programs involving recreational divers are increasingly used to monitor subtidal marine environments. These programs employ simplified protocols to encourage participation, yet their effectiveness as surrogates for conventional monitoring remains insufficiently evaluated and persistent concerns about data quality also limit the broader use in ecological research. To address these issues, we used surveys of artificial reef benthic colonization conducted by non-professional and professional scientists using a restricted taxa list including macroalgae, fish and epifauna. Agreement metrics and linear mixed models were used to investigate agreement between and within diver groups, while taxon-specific agreement provided insights into sources of variability. In addition, we compared the trajectories of community composition from participatory science data over two years with those from an independent image-based monitoring to evaluate the ability of participatory science to capture changes in community composition. High and consistent levels of agreement were found within and between diver groups (average Percent Agreement ~ 0.8; Gwet’s AC1 ~ 0.7), meeting the criteria for high data quality. Although taxon-specific agreement was generally moderate to high (AC1 > 0.4), variation among taxa suggested volunteer preference for charismatic taxa, giving opportunities to improve protocols and training. Furthermore, significant concordance was found between participatory science and image-based monitoring (Procrustes correlation = 0.85, p < 0.01), demonstrating the reliability of simplified protocols for detecting spatio-temporal trends in community composition. Overall, this study supports the high quality of data produced by well trained non-professional scientists, and emphasizes the value of structured yet straightforward approaches for monitoring underwater benthic biodiversity.