Structure‐from‐motion photogrammetry demonstrates that fine‐scale seascape heterogeneity is essential in shaping mesophotic fish assemblages

Benthic components of tropical mesophotic coral ecosystems (MCEs) are home to diverse fish assemblages, but the effect multiscale spatial benthic characteristics on MCE is not well understood. To investigate influence fine-scale seascape structure and broad-scale environmental fish, we surveyed assemblages in Seychelles at 30, 60 120 m depth using submersible video transects. Spatial pattern metrics from ecology were applied quantify composition, configuration terrain morphology structure-from-motion photogrammetry multibeam echosounder bathymetry explore seascape–fish associations. Hierarchical clustering abundance biomass data identified four distinct separated by geographic location, also significantly influenced variations structure. Results further revealed variable responses assemblage (fish biomass, abundance, trophic group richness, Shannon diversity) heterogeneity different depths. Sites with steep slopes high complexity hosted higher shallower (30–60 m) positively associated aggregated patch mixtures coral, rubble, sediment macroalgae shapes. Deeper (120 relief structural local variability substratum cover. Our study demonstrates potential quantifying delineate fish–habitat Furthermore, incorporating a finer-scale perspective proved valuable explain compositional patterns assemblages. As developments marine surveying monitoring MCEs continue, suggest that future studies remotely sensed can provide insights will both ecologically meaningful operationally relevant conservation strategies.