Abstract

Growing artificial infrastructure in coastal areas is altering natural habitats and impacting biodiversity. The composition of construction materials can influence biological colonisation; however, their effects on native and non-native macrobenthic assemblages and their functional traits remain understudied. This study evaluated the effects of concrete mixtures on species richness, percent cover, and the taxonomic and functional structure of macrobenthic communities established in port environments. Four concrete mixtures incorporating industrial by-products as partial sand substitutes were evaluated [10 % steel sludge (CS), 20 % mussel shells (MS), 1 % straw fibres (SF), and a combination of CS and MS] and compared to reference concrete. Plates were suspended in the subtidal zone at two port sites and assessed after 3, 6, and 12 months. While an increase in taxonomic and functional richness and cover was expected —reflecting enhanced bioreceptivity through surface texture (provided by shells and fibres) and potential chemical effects (sludge)— no significant differences were found as compared to conventional concrete. After 12 months, MS plates showed higher richness and MS and SF plates greater cover, but these effects were weak and insufficiently clear to support definitive conclusions regarding material effects. Although bioreceptivity was not enhanced compared to conventional concrete, the neutral effects support the potential use of more sustainable materials, reducing natural aggregate use while incorporating materials currently treated as residues. © 2025 Elsevier Ltd