An Assessment of Artificial Floating Islands as a Method of Habitat Creation in Marine Environments

Abstract

Most megacities are located adjacent to the coast due to the continuous seaward migration of human populations; a process referred to as marine urban sprawl. The subsequent hardening of the natural coastline has caused the loss and degradation of coastal habitats. In order to halt, mitigate and compensate for further losses of biodiversity, it is important that habitat restoration techniques with involve ecological engineering are considered. Artificial floating islands (AFIs) are a habitat creation method used to improve water quality and support biodiversity in aquatic environments. This study aimed to assess the installation of AFIs as a restoration tool in heavily modified coastal water bodies. That included investigating: the suitability of halophytes for transplantation into the AFI matrix; the biofouling communities that establish on the AFIs; the abundance, species richness and behaviour of fish in association with AFIs; the density and behaviour of birds in association with the AFIs; and the public perception of current environmental concerns and therefore, opinion on AFIs as an ecological engineering method. Based on the results of this study sea purslane (Halimione portulacoides) would be recommended for transplantation on AFIs installed in saline environments. The invertebrate community assemblages were notably controlled by the primary settlement of blue mussel (Mytilus edulis) and Australian tubeworm (Ficopomatus enigmaticus). Juvenile phase European sea bass (Dicentrarchus labrax) and gull (Laridae) spp. foraged on the benthic invertebrates that fouled the AFIs underside and European eel (Anguilla Anguilla) rested in the matrix. The public supported the use of AFIs in coastal environments but concerns regarding maintenance and degradation were raised. In conclusion, this study highlighted the importance of AFI size, structure, location and vegetation cover as these factors influence the species composition, degree of isolation and environmental exposure, contributing to the overall success of AFI deployments in heavily modified coastal water bodies.