Ecological drivers of subseafloor microbiomes of the Puerto Rico Trench

Hadal ecosystems belong to the least understood environments on Earth. It is commonly thought that microbial communities in hadal trenches are composed of pressure-tolerant taxa that are remnants of shallower surface communities and piezophilic taxa that are specifically adapted to high pressure. However, few studies have conducted systematic comparisons of microbial communities across the full depth range of a hadal trench. In this project we combined 16S rRNA amplicon and metagenomic sequencing to investigate the composition and functional potential of sediment communities inhabiting the Puerto Rico Trench from shallow (<500 m) to hadal depths (>8300 m) in up to 20 meters below the seafloor. Our results indicate that subseafloor communities in this region are distinct from overlying seawater communities and are shaped by both water depth and sediment geochemistry. These data advance our fundamental understanding of hadal microbiomes and provide insights into their adaptation to this extreme environment.