Seamount larval dispersal networks: A potential strategy for conserving ecological connectivity from deep-sea mining.

Seamounts are unique habitats in the deep sea facing anthropogenic stressors, including future deep-sea mining. To conserve patchy marine habitats such as seamounts, it is critical to design conservation area networks that maintain connectivity by larval dispersal. This study conducted biophysical modeling to quantify larval dispersal among 18 seamounts in the Northwest Pacific, within the scope of a regional environmental management plan for mining under development by the International Seabed Authority. Seamounts formed a single dispersal network, but excluding seamounts with mining potential showed the network could become fragmented. Two seamounts whose mining potential was relinquished in 2024 were identified as key stepping stones, suggesting that environmental conservation at these two seamounts can contribute to maintaining a single dispersal network. Predominant eastward or westward currents, likely related to the North Equatorial Intermediate Current, made the upstream, distant seamounts vital larval sources. Trajectories of Argo floats and gene flows of amphipods provided physical and biological support for the modeled dispersal. This study highlights the potential for effective conservation area placement based on a seamount network connected by upstream-based larval dispersal.