Next generation sequencing of 16S rRNA genes in marine biofilm from Bioshelter tiles

Coastal urbanisation has resulted in the proliferation of artificial structures into the marine environment. These structures are not surrogates for natural habitats because they tend to support different communities and can facilitate the spread of non-indigenous species (NIS). Modifying the physical design and materials used in marine construction could enhance recruitment by desired native species or inhibit NIS and therefore reduce these negative impacts. Here we modified physical complexity (flat, complex) in combination with different material mixtures and investigated recruitment of sessile marine species. Flat and complex tiles (25 x 25 cm) were cast from three concrete mixtures, including standard concrete as well as concrete in which 50% of the aggregate was replaced by either oyster shell or vermiculite. Recycled oyster shell was used to reduce the environmental footprint of the concrete mixture and encourage native oyster settlement, whereas vermiculite was used due its porous and lightweight properties that improved ease of deployment and provided a microtexture for settlers. Tiles were randomly arranged on frames and deployed in the intertidal zone in Blackwattle Bay, Sydney Harbour, Australia. Colonisation was assessed after six weeks with photographs and DNA sequencing of the biofilm community and after six months with photographs. The results of this research will provide guidance on the design of artificial structures to reduce ecological impacts.