Seamount seascape composition and configuration shape Southwest Indian Ridge fish assemblages

Seamounts are commercially important fishing grounds. Yet, little is known about their physical characteristics as fish habitat, for informing conservation and ecosystem-based management. This study examines how multiscale seabed spatial heterogeneity influences families at three Southwest Indian Ridge seamounts (Coral Seamount, Melville Bank Atlantis Bank). We quantified seascape from bathymetry geomorphological habitat maps identified 15 focal video data. Fish-habitat associations were examined using pattern metrics that measured terrain morphology, composition (variety relative abundance of patch types) configuration (spatial arrangement patches). Broader context was characterised by geographic location water depth. Multivariate regression trees random forests modelled fish-habitat the most influential explanatory variables. Assemblage individual strongly influenced depth, finer scales (500 m buffers) helped explain associations. Spatially continuous summit complex shaped ridge features supported high diversity commercial families. Metrics (i.e., size, shape structural connectivity) had higher predictive power than commonly used in developing proxies deep-water species biodiversity. These outcomes indicate metrics, applied on land shallow marine environments, also relevant environmental predictors distributions deep-sea environments. highlight strong dependency depth-specific hinder attempts to draw wider generalisations fish-seascape linkages seamounts. • Fish assemblages mainly driven Landscape ecology assemblages. Metric combinations ecological patterns, with similarities between co-occurring Main drivers proportion continuity shape.