Microbiological Survey of the San Pedro Basin Subseafloor

Marine subseafloor sediments host extensive microbial communities that drive global biogeochemical processes. Despite its proximity to one of the most densely populated and economically important coastal regions in the world, the sub-benthic ecology of the San Pedro Channel, the waterway separating Los Angeles County from Santa Catalina Island, remains largely uncharacterized. To establish the foundational knowledge required for future impact assessment studies, we initiated a sediment coring survey that generated a water and sediment depth standardized transect across the sloping flanks of the San Pedro Basin. Here, we describe the early development of an integrated subseafloor microbiological catalogue for this region of intense maritime activity incorporating molecular ecology, microbial isolation and cultivation, and physiological assays. This initial effort is designed not as a direct comparison between basin flanks, but as a baseline assessment that captures ecological and microbiological variation across paired sides matched in water column depth and sediment depth beneath seafloor. Accordingly, we provide a cross-channel coordinated dataset of subseafloor microbial communities and cultivated representatives from San Pedro Basin sediment, offering a critical starting point for understanding natural variability and for detecting potential signatures of environmental or anthropogenic disturbance. Ultimately, this baseline will support long-term monitoring efforts and supply a curated collection of isolates for future experimental microbiology and comparative genomics research.