Abstract

This study was carried out to address how hydrodynamic dispersal and local geochemical features shape marine sediment microbiomes across geographic distance. The work follows a study that investigated how regional water masses, their stratification, and physical properties shape surface sediment microbiomes on continental shelves. This project focused on two groups of sediment samples from the Alaska Beaufort Shelf, and the Hikurangi Margin of New Zealand. The cores were selected based on geochemical profiles of pore-water sulfate, chloride, and dissolved inorganic carbon concentration, and sediment methane concentration. Cores were pair matched with a geochemically analogous core. The study tested the hypothesis that in geochemically analogous environments separated by geographic distance, but within the same ocean mass, the same communities would be present in similar relative abundance at different geochemical horizons down core: consequently, the same biogeochemical functions would be performed by like taxonomic groups. The study used a computational approach to extract functional data from tag-sequence data. The analysis demonstrated in samples near the sediment-water interface there was covariance in terms of taxonomic composition and metabolic function across sites. However, in general, down core, in geochemically analogous settings from different locations, metabolic functions were carried out by different taxonomic groups. The work identified limitations with current databases to extract functional information from sequence data, but provides a potential framework for extracting information from archived datasets, where real-time functional analyses are not possible.