Seamounts and giant carbonate mounds drive bio-physical connections in the deep-sea: Two case studies from the North Atlantic.

Seamounts and carbonate mounds are ubiquitous features of the global deep seascape. They often provide habitat for unique benthic species communities and support increased production and aggregation of phytoplankton, zooplankton, micronekton, and fish. Seamounts and carbonate mounds interact with the surrounding currents generating flow phenomena over a wide range of spatial and temporal scales including stable Taylor caps, energetic internal waves and turbulent mixing, all with the potential to enhance productivity, biomass, and biodiversity in an often food limited deep-sea environment. We present hydrodynamic and ecological framework conditions at two contrasting topographic features in the North Atlantic, Great Meteor Seamount and Haas Mound. Great Meteor Seamount is of volcanic origin and one of the largest seamounts in the subtropical North Atlantic rising from 4200 m depth at the seafloor to a summit depth of 270 m. Great Meteor Seamount shows remarkable endemism in meiofaunal groups of copepods and nematodes. Haas Mound is one of the largest biogenic carbonate mounds of the Logachev mound province along the Southeast Rockall Bank in the Northeast Atlantic with a species rich benthic fauna dominated by the cold-water coral Desmophyllum pertusum (Lophelia pertusa). We used results from hydrodynamic models to identify the physical processes, which potentially support seamount and carbonate mound biodiversity. The models employ high-resolution local bathymetry, basin-scale lateral forcing and tidal forcing. Our model simulations provide a detailed three-dimensional picture of the fine-scale motions and physical processes, which potentially drive bio-physical connections such as particle retention and continuous or episodic food supply to benthic communities.