Tube worms like Lanice sp. and Sabellaria sp. are ecologically important in the North Sea because of their reef-building capacity, leading to increased species diversity by creating complex structures on the seabed. These reefs provide a more stable environment with more shelter, strengthening the food chain and also offering protection against erosion by retaining sand. As a consequence, next to gravel beds and oyster banks, biogenic reefs of Lanice and Sabellaria are one of the three priorities for marine nature restoration in the BPNS, as stipulated by the Federal Public Service Health, Food Chain Safety and Environment (https://www.health.belgium.be/nl/prioriteren-maatregelen-0). Numerous studies and projects (BELREEFS, Reefcovery, BlueConnect, etc.) are already underway for the first two priorities, which are largely associated with hard-bottom substrates. Lanice aggregations and Sabellaria reefs, on the other hand, although each bound to specific environmental conditions, naturally occur on soft substrates. However, knowledge about these species, their occurrence, and how they can be stimulated and restored is currently rather limited. Few studies have been conducted on this topic, and these moreover focus on the intertidal zone (e.g., Coastbusters Lanice). In the proposed study we intend to lay the foundation for nature restoration/creation with tube worms in the subtidal zone. Based on the business model of the project partners we have identified a number of knowledge gaps that are crucial to develop new business activities re. tube worm habitat restoration: Firstly we want to explore if multibeam echosounder (MBES), a very common and widely-used technique in various maritime activities to map the seabed, can also be applied to detect tube worm aggregations and thus ascertain habitat suitability (WP1). To investigate this, a multibeam campaign will be executed in the subtidal Project zone C of Seafarm Westdiep. Secondly, we want to study the feasibility of modifying local environmental conditions, for example through addition of materials, to promote tube worm recruitment and growth (WP2). For both business cases we will analyse practical applicability based on relevant technical and economic criteria (e.g. cost-benefits, integration with other activities, geographical scaling, …) and map the financing possibilities in order to validate the business case. We will moreover elucidate the legal framework and clarify the permitting process for nature-supporting activities based on tube worms. Lastly, we want to investigate whether project zone C is a representative pilot location for a broader follow-up study (for example demonstrating substrate addition to stimulate tube worm development). Based on the knowledge gained within the current feasibility study, we then foresee a number of follow-up projects in order to further develop and validate the different business cases.
