The impacts of human-made structures on larval connectivity in the northern North Sea

Abstract North Sea human-made, offshore structures (e.g. oil/gas platforms, offshore wind farms) provide a hard substrate habitat for benthic marine species which can spread between sites during their larval stage. Here, we aim to address how the installation of additional human-made structures, like new wind farms, or decommissioning of existing ones, like oil and gas platforms at the end of service, contribute to changes in larval connectivity. We use particle tracking model simulations to assess the ecological connectivity of benthic species in the northern North Sea during two contrasting years to highlight seasonal to annual variability. The methodology of releasing an extensive set of particles over a wide area produces our Retrospective Particle Tracks dataset. The sets of simulations can be interrogated to understand if additional human-made structures placed in any locations in the northern North Sea could potentially affect the ecological connectivity. Network metrics were used to identify connectivity between sites. Clustering of existing structures identifies a region that acts as an interchange between other structures which may otherwise only be connected during intermittent periods. The addition of new human-made structures located in areas with stronger residual current flow would enhance the connectivity.