Seafloor‐image analysis techniques to highlight the role of substrate as a driver of benthic community structure in Arctic cold seep areas

Cold seeps are biodiversity hotspots that significantly affect sediment geochemistry in marine environments. Although seepage-driven substrate modifications are ecologically significant, their interactions with benthic community structure remain poorly understood. This knowledge gap largely reflects the challenge of obtaining high-resolution seafloor data to capture the fine-scale organisms-substrate relationships. Here, we used high-resolution seafloor imagery to investigate a seepage area offshore northern Svalbard (~ 150 m of water depth). Two orthomosaics (spanning ~ 2261 m2 and generated through photogrammetry applied to underwater videos collected using a remotely operated vehicle) were analyzed to classify visible epibenthic fauna and describe seafloor substrate changes. Epibenthic fauna was annotated to the lowest possible taxonomic level, while object-based image analysis facilitated a quantitative and repeatable classification of substrates into four distinct classes. Integrating faunal and substrate data allowed us to quantify community patterns relative to seafloor morphometric parameters. The network plot revealed substrate class similarities and faunal colonization preferences, particularly where methane-derived authigenic carbonates are present. Our results demonstrate that seep-associated substrates play a crucial role in shaping benthic community structure. However, methane-derived authigenic carbonate formation further amplifies these effects, although its relationship with specific sediment types (e.g., coarse- or fine-grained) remains unclear. This study demonstrates a robust framework for future ecological assessments of seep environments, emphasizing the interplay between gas seepage, sedimentological attributes, and their combined impact on benthic community structure.