Enhancing the larval settlement of Lanice conhilega with an optimized screening method of artificial substrates


The Belgium sandy coastline is very vulnerable to erosion, hence, the development of sustainable and nature-based coastal protection solutions is a key feature. Enhancing the settlement of the ecosystem engineer Lanice conchilega (Pallas, 1766) which stabilizes the sediment bed could be a solution combining ecosystem functioning enhancement and erosion protection. Recirculating Aquaculture System (RAS) allows testing the potential of a wide number of innovative substrates in a fast and controlled manner, provided that adequate water mixing is met (Wyns et al. 2020). Optimal flow conditions in the RAS were obtained through the addition of a new water inlet pipe design and a regulated flow rate at 560L/H using a flow meter. This was documented based on floating particle homogeneity using picture analysis. Eight artificial substrates were ranked in regards to their efficiency to capture passively floating plastic particles and their influence on surrounding flow velocity (Acoustic Doppler velocity meter). Finally, one substrate candidate was shown to significantly enhance the settlement of L. conchilega: “geo-textile 3D knitted fabric based on PES knit and PA spacers with wood sticks (680sticks/m2)”. Altogether, the results of this thesis showed that laboratory experiments are useful to develop sustainable and nature-based coastal protection solutions and encourage further research towards large-scale testing of the artificial substrate.

Key words: coastal erosion, restoration, Lanice conchilega, larval settlement, recirculation aquaculture system, acoustic velocity meter, artificial substrate, geotextiles, distribution of particles