A resilient ecological network of shipwreck-associated communities in the North SeaOcean Sprawl

Peter Almond¹, Clare Fitzsimmons¹, William Reid¹

¹Newcastle University, UK

Shipwrecks, as artificial reefs, are unique seafloor habitats, promoting settlement, abundance and diversity through their provision of hard, complex substrate to systems which may otherwise lack these features. As marine habitats, shipwrecks are unique due to their continued degradation and reduction in complexity over time. In a North Sea context, where the seabed has been altered by over 250 years of overfishing and disease into a mostly mud-dominated, soft sediment habitat, shipwrecks provide structure for species that may have seen their ranges significantly depleted. The North Sea contains a high number of wrecks due to the unique industrial, historic and cultural heritage of the region, with over 30,000 known shipwrecks within the UK’s North Sea EEZ. Structure-from-motion (SfM), three-dimensional photogrammetry as a method for investigating trends in biology and ecology is increasingly cost effective, and in recent years has been applied to marine environments to answer a range of ecological questions. The ability to capture detailed and accurate models of large structures efficiently using photogrammetric methods has made shipwrecks an ideal target for this. This study combines in-situ diver video surveys, baited cameras, and Structure-from-Motion (SfM) photogrammetry to assess sessile benthic and mobile demersal species abundance, diversity, and richness on shipwrecks off the North-East coast of England. Fine-scale structural complexity was measured alongside wreck-specific factors like age, depth, current exposure, area, and location. Results revealed regional and wreck-specific differences, with more structurally complex wrecks supporting greater diversity and abundance, likely due to increased settlement space and ecological niches. Insights were also gained into how community composition may shift as shipwrecks degrade and into their broader ecological impacts. This data was then used to inform two hydrodynamic larval-dispersal models, one regional and one North Sea-wide, to simulate larval movement of keystone taxa and commercially significant species using the known positions of shipwrecks and other artificial structures as settlement points. These models were used to inform a Network Analysis of the North Sea seabed, to answer questions of resilience within this ecological network, and how the system may respond to both anthropogenic stressors and climate warming scenarios.