Material type affects the community composition and abundance of hard-substrate assemblages in a sedimentary Atlantic estuary

Abstract

Hard-substrate epibionts have an important role in estuaries; they improve water quality, form habitat, and influence food webs. Coastal urbanization converts natural hard substrates (e.g. oyster reefs and rocky shorelines) into artificial structures, which do not support the same hard-substrate communities. Material composition may be a driving factor behind this difference, so interest is growing in how material type can be used to create marine structures that serve an ecological role. However, this research has mainly been restricted to rocky shorelines. We address this gap by asking how material type affects hard-substrate assemblages in a sedimentary Atlantic habitat. We deployed panels of wood, PVC, and 2 different concrete mixes in Galveston Bay, TX, USA, for 3 mo. Unique communities formed on different materials, which may alter ecosystem services if scaled to large development projects. Material type had a limited effect on richness but strongly affected total cover and biomass, both of which are important metrics for ecosystem function. Across all measures, one concrete mix showed the most potential to serve a beneficial ecological role. Our findings highlight the importance of material type in the design of marine structures in sedimentary Atlantic habitats.