Building Like a Worm: Developing Sabellaria-Inspired Artificial Reef Modules for Intertidal Placement in the Wadden Sea

Reef-forming species in the Wadden Sea and North Sea have declined severely over the past decade, threatening the local biodiversity. Artificial reef deployment offer a promising method for restoration, yet current designs are largely confined to subtidal, sediment-poor environments. Limiting the range of species and locations they can support.

This project investigates the design of an artificial reef module intended to be placed in the intertidal zone while supporting the settlement of the Ross worm, Sabellaria spinulosa. This is a species with no prior history in artificial reef development.

The work operates at the intersection of computational design, clay additive manufacturing and marine ecology, and adopts a research through design methodology based on biomimimetic principles. Iterative prototyping and field evaluation serve as a primary modes of knowledge production in this process. The project studies the honeycomb worm, S. alveolata, as a structural model species, whose naturally constructed hummock reefs provided the morphological analogy for the design process.

The design process was structured around three interrelated research strands. First, a literature review and expert consultation established the biological requirements of S. spinulosa and S. alveolata. Second, field trips to the Wadden Sea, combined with a review of intertidal failure mechanisms, identified the dominant structural challenges facing deployed reef modules: scouring, subsidence, toppling, shifting, and sediment infilling. Which were further supported by literature. Third, iterative design and fabrication using Rhinoceros, Grasshopper, and a clay 3D printer produced a series of prototypes evaluated through density and porosity testing, explorative field testing at Scheveningen, four day field testing at Texel, hydrodynamic drag calculations, bio-attractivity calculations, and expert interviews with Sabellaria specialists and industry practitioners in artificial reef development.

The resulting design. Alveo, consists of two primary components: a Habitat and an Anchor, connected by a narrowed Neck. The overall geometry is derived from S. alveolata hummock proportions and geometry. The anchor employs sediment entrapment and burial as its primary stabilisation mechanisms, directly translating a biological behaviour observed in S. alveolata reefs. The narrowed neck reduces scour initiation at the most hydrodynamically exposed point of the structure, the feature was inspired by observations from fieldtesting. The habitat geometry balances settlement surface quality against hydrodynamic drag, with the surface complexity being achieved through G-code controlled toolpath manipulation.

The final design is fabricated from earthenware clay containing 25% chamotte, fired at 1050°C, yielding a density closely matched to both the surrounding sediment and measured S. alveolata reef material. The total module weighs 14.2 kg of which 3.7 kg is entrapped sediment, while having a 65%-35% weight distribution of the respective Anchor and Habitat. The model is approximately 35 cm high, 35 cm wide and 24 cm deep.

The project proposes a structurally tested artificial reef module developed through the integration of species-specific ecological knowledge, site-specific failure analysis, computational modelling and 3D clay printing alongside a set of design principles identified through the Research through Design framework.