Multiscale characterization of Solito seamount: a unique ecosystem with high conservation value

Solito seamount is a volcanic seamount rising more than 3,500 m from the abyssal plain off northern Chile, located at a biogeographic transition between the Nazca–Desventuradas and Juan Fernández systems in the southeastern Pacific Ocean. Here, we present the first integrated ecological characterization of this previously unexplored seamount using high-resolution bathymetric mapping, remotely operated vehicle surveys, and hydrographic profiling. Solito exhibited a heterogeneous benthic landscape composed of volcanic rocky outcrops, coral rubble fields, and soft-sediment habitats distributed across distinct depth strata. Hydrographic analyses revealed the influence of Subtropical Water, Equatorial Subsurface Water, and an Oxygen Minimum Zone, generating pronounced vertical gradients in temperature, salinity, and dissolved oxygen. A total of 131 morphotaxa across eight phyla were recorded, predominated by cnidarians, echinoderms, and crustaceans. Community composition varied significantly with depth and substrate type, with hard substrates and habitat-forming taxa supporting higher faunal density and structural complexity than soft-bottom habitats. The occurrence of vulnerable habitat-forming taxa, including cold-water corals and sponges, together with commercially important species such as Chaceon chilensis, Beryx splendens, and Hoplostethus atlanticus, highlights the ecological importance of this ecosystem. Regional faunal comparisons suggest biogeographic affinities with neighboring ridge systems. Visual surveys documented limited evidence of recent anthropogenic disturbance. These findings establish the first ecological baseline for Solito seamount and highlight its potential relevance for biodiversity conservation and spatial management in the southeastern Pacific.