Near-inertial internal waves funneled into Taylor caps shape seamount tops, with implications for biodiversity in the deep ocean.

Abstract

Internal waves are energetic and ubiquitous in the ocean and their interactions with submarine topography could drive sediment resuspension and reshape seafloor substrate. However, the mechanisms governing these interactions are largely unknown. Here, using observational and reanalysis data at Pacific deep-sea seamounts, we show how near-inertial internal waves (NIWs) may affect substrate variability via interactions with seamounts. Taylor caps with anticyclonic vorticity generated above the seamounts can act as a "chimney" that focuses NIW energy. The NIWs can further undergo reflection at the summits and generate strong bottom currents to erode sediments. As wind energy input to NIWs increases with latitude, this process could contribute to the removal of sediments at seamount summits further north than 20°N, exposing the rock outcrops needed for biogenic structuring species and thus boosting species richness. Given that Taylor caps occur at ~93% of the global seamounts, our findings suggest a wave-topography interaction that could shape the substrate and enrich the biodiversity in the deep ocean.