Depth and substrate type influence community structure and diversity of wood and whale-bone habitats on the deep NE Pacific margin

Whale bones and wood on the deep-sea floor provide resource pulses that support characteristic faunal assemblages in an otherwise food-poor environment. To isolate role of bathymetric geographical drivers organic-fall diversity community structure, study organic-rich substrates similar sizes, qualities, seafloor durations is necessary. We used a comparative experimental approach to examine roles depth, location, substrate type structuring assemblages. Four free-vehicle landers containing replicate wood, whale-bone, inorganic hard (control) were deployed for 15 mo at depths ~1600 ~2800 m, spaced ~400 km along Washington-Oregon (USA) margin. The collected total ~84890 macrofaunal individuals 144 species. Wood, bone, control supported with different structures all landers. Community composition was significantly between locations depths, indicating variability regional scales. Wood blocks m heavily degraded by wood-boring xylophagaid bivalves. Xylophagaid colonisation lower deeper blocks, which we hypothesise results partly from propagule supply as falls decrease abundance distance terrestrial sources wood. Bone-eating Osedax colonised whale bones, but bone degradation low compared some NE Pacific duration; nonetheless, exhibited reducing conditions sulphophilic Our demonstrates quantitatively co-located highly distinct, species-rich thus promote biodiversity floor.