Seafloor topography structures subseafloor microbial communities in the Puerto Rico Trench
- 1University of Rhode Island
Abstract
The influence of seafloor topography on subseafloor microbial communities is poorly understood. In this study, we systematically sampled subseafloor sedimentary microbial communities and pore-water geochemistry at bathyal, abyssal, and hadal water depths of the Puerto Rico Trench. The Puerto Rico Trench exhibits vertical relief of over 8 km with seafloor topography shaped by active plate tectonics and characterized by a very steep southern wall and active mass wasting. Sampling across these features, we find that subseafloor microbial communities are influenced by topography in the following two ways. First, subseafloor sediment in the deepest part of the trench is anoxic, enriched in organic matter due to mass transport of sediment from shallower water depths, and contains an anaerobic subseafloor community that is quite distinct from the anaerobic subseafloor community in anoxic sediment at bathyal depths. The difference between these bathyal and hadal subseafloor anaerobic communities is consistent with influence of water-depth-related physical properties on subseafloor community composition. Second, subseafloor sediment remains oxygenated for meters below seafloor on steep slopes within the bathyal zone, an abyssal topographic high within the trench, and the abyssal plain seaward of the trench subseafloor, likely due to limited sediment accumulation, which selects for the presence of aerobic microbial communities. The difference between these bathyal and abyssal aerobic subseafloor communities and the anaerobic communities at bathyal and hadal depths reflects the role of seafloor topography in structuring subseafloor availability of redox reactants, which in turn drives the activities and composition of subseafloor microbial communities.
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BibTeX
@misc{breusing2026seafloor,
title = {{Seafloor topography structures subseafloor microbial communities in the Puerto Rico Trench}},
author = {C. Breusing and W. D. Orsi and M. Desmarais and A. M. Plominsky and I. Aylward and D. Graham and R. Pockalny and S. Rivera Soto and B. Saucedo and D. C. Smith and E. A. Solomon and J. J. Sostre-Cortes and A. J. Spivack and T. Walton and L. M. Wehrmann and Y. Zhang and D. H. Bartlett and S. D'Hondt},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.13.758824},
url = {https://www.biorxiv.org/content/10.64898/2026.10.13.758824v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Seafloor topography structures subseafloor microbial communities in the Puerto Rico Trench
AU - C. Breusing
AU - W. D. Orsi
AU - M. Desmarais
AU - A. M. Plominsky
AU - I. Aylward
AU - D. Graham
AU - R. Pockalny
AU - S. Rivera Soto
AU - B. Saucedo
AU - D. C. Smith
AU - E. A. Solomon
AU - J. J. Sostre-Cortes
AU - A. J. Spivack
AU - T. Walton
AU - L. M. Wehrmann
AU - Y. Zhang
AU - D. H. Bartlett
AU - S. D'Hondt
PY - 2026
DA - 2026/10/13
PB - bioRxiv
DO - 10.64898/2026.10.13.758824
UR - https://www.biorxiv.org/content/10.64898/2026.10.13.758824v1
AB - The influence of seafloor topography on subseafloor microbial communities is poorly understood. In this study, we systematically sampled subseafloor sedimentary microbial communities and pore-water geochemistry at bathyal, abyssal, and hadal water depths of the Puerto Rico Trench. The Puerto Rico Trench exhibits vertical relief of over 8 km with seafloor topography shaped by active plate tectonics and characterized by a very steep southern wall and active mass wasting. Sampling across these features, we find that subseafloor microbial communities are influenced by topography in the following two ways. First, subseafloor sediment in the deepest part of the trench is anoxic, enriched in organic matter due to mass transport of sediment from shallower water depths, and contains an anaerobic subseafloor community that is quite distinct from the anaerobic subseafloor community in anoxic sediment at bathyal depths. The difference between these bathyal and hadal subseafloor anaerobic communities is consistent with influence of water-depth-related physical properties on subseafloor community composition. Second, subseafloor sediment remains oxygenated for meters below seafloor on steep slopes within the bathyal zone, an abyssal topographic high within the trench, and the abyssal plain seaward of the trench subseafloor, likely due to limited sediment accumulation, which selects for the presence of aerobic microbial communities. The difference between these bathyal and abyssal aerobic subseafloor communities and the anaerobic communities at bathyal and hadal depths reflects the role of seafloor topography in structuring subseafloor availability of redox reactants, which in turn drives the activities and composition of subseafloor microbial communities.
ER -