This project combines eDNA water sampling techniques and ROV video recording to quantify the bio-colonisation and reef-associated fish community of the artificial reef units over the deployment period of at least five years. The reef units include removable samples, which can be lifted by ROVs for closer analysis of the epifauna prior to recovering entire units at the end of the project. A concrete control block was also deployed alongside the reefs. The results will compare the impact of the artificial reefs on biodiversity in relation to baseline conditions and the control unit.

To maintain accessible costs for deployment and monitoring, the project programme is synced to the existing maintenance schedule at the site. This means that the deployment, monitoring visits and decommissioning will take place during planned vessel operations, removing the need to procure a separated vessel for the monitoring campaign.

Description of the used artificial reef:

Standalone artificial reef enhancement

Function: Artificial reef add-on, to provide habitat for Atlantic Cod and Ross worm, enhancing the biodiversity of scour protection used in the North Sea.

Weight: 4.5t

Dimensions (LxWxH): 1.8m x 1.6m x 1.6m

Habitat features:

• Textured sides for shellfish settlement, algae colonisation and coral growth.
• Large tunnels provide shelter for juvenile fish such as cod while preventing sedimentation.
• Add-on wood and metal panels facilitate the colonisation of a broader range of biodiversity.
• Small tunnels and holes for crustaceans and reef dwelling fish such as blennies.

Customisation: Textures, material composition.

Installation: Reef units were installed from a crane with a large strop connected through the unit. The strop was released using an ROV. Other deployment methods could also use automatic or acoustic release mechanisms as alternatives.

• To ensure relevant project outputs, research should be tied to real world scenarios whenever possible, such as upcoming policies or industry requirements.
• Maximize vessel time by combining projects that require sea travel with partners where possible.
• Don’t let the “perfect” become the enemy of the “good”. Not all variables can be controlled. Make use of any data that can be collected, or that already exists, to inform research decisions.
• Allow for extended lead times during project planning to understand the decommissioning and permitting requirements at the deployment site, as this can restrict the options for pilot study design.