Eco-engineering and management strategies for marine infrastructure to reduce establishment and dispersal of non-indigenous species

Habitat modification and the introduction and establishment of non-indigenous species (NIS) are two of the greatest threats to global biodiversity. Human modifications of marine habitats include the introduction of boating infrastructure, coastal defences and offshore energy installations that are occurring at an increasing rate. These artificial structures are now widely recognised as providing opportunities for the establishment and dispersal of non-indigenous fouling species in new regions. This is driving increased interest into how structures might be designed and built to limit their suitability for invasive species. At the same time the potential for artificial habitats to provide habitat to native and threatened species means that the control of NIS on these structures should not just rely on antifouling. Green or eco-engineering aims to incorporate ecological theory and principles into the design of engineered structures. When combined with other management strategies that aim to increase the resistance of recipient environments there is the potential to enhance practical barriers against invaders in an increasingly developed ocean. Here I explore examples of NIS facilitation by artificial structures and the ecological theories that could be used to reduce opportunities for NIS establishment and spread. Examples include (1) manipulating the physical and chemical properties of structures to enhance native recruitment over NIS, (2) enhancing resource use of structures by native species through pre-seeding, (3) providing opportunities for native grazers and predators to easily access structures, and (4) considering the timing of construction/maintenance/decommissioning for artificial structures such that resources are not made available when propagule pressure is also high. These examples are not exhaustive, but rather provide a discussion point for managers of biological invasions to generate further research and application over larger spatial scales.