Optimizing coral reef monitoring: species traits and habitat factors predict visual census performance

Accurate underwater visual census (UVC) of fish community structure is essential for monitoring ecosystem health, managing fisheries, and evaluating response to stressors on coral reefs. However, comparisons between survey methods often reveal significant differences in species detection and estimated density. The authors of this study evaluated the extent to which generalizable species traits (nocturnality, water column position, aggregation, crypsis, coloration, shape, size) alongside habitat characteristics and survey area influence the relative performance of three UVC methods: stationary visual censuses (SVCs), belt transects, and REEF roving surveys. By comparing density estimates for 165 fish species gathered simultaneously via these methods at 42 reef sites in the Florida Keys, USA, the authors demonstrated that multiple fish traits and coral cover signficantly influence density differences among survey types. Data from the REEF Volunteer Fish Survey Project database were used in the analysis. The study highlights the importance of considering the traits of focal taxa alongside management objectives when selecting monitoring techniques.