Stakeholders support marine eco-engineering, but what are the perceived benefits and who should pay?

Despite the ecological and socio-economic benefits of nature-based solutions (NbS), the application of ecological principles to the design of seawalls (termed 'seawall eco-engineering') to mitigate their impacts remains low. We investigated stakeholder perspectives of, support for and willingness to pay (WTP) for seawall eco-engineering in one of the most diverse and urbanised harbours in the world, Sydney Harbour, in Australia. Using a series of workshops and surveys targeting the general public, Local Government, built environment and natural environment professionals, we identified and ranked perceived risks and benefits of eco-engineering seawalls, the most common infrastructure in the Harbour. Additionally, WTP for seawall eco-engineering was investigated using an existing, large-scale eco-engineering project. Overall, workshop participants rated benefits of seawall eco-engineering to be almost double the risks. The key perceived benefits were increased habitat/biodiversity, improved water quality and enhanced environmental stewardship/awareness. Key perceived risks were potential damage to infrastructure and use of greenwashing to facilitate new development. Across all stakeholder groups, participants were very supportive of statements regarding the benefits of eco-engineered seawalls and the need for eco-engineering principles to be included in the design of new seawalls. Despite strong support for seawall eco-engineering, WTP was estimated at one third of the actual cost and was, in part, attributable to a lack of a shared evidence base from successful projects, and unclear guidance and policy around implementation. Synthesis and applications: Our results showed that establishing rigorous monitoring and evaluation programs that facilitate cost-benefit analyses are critical to enhancing WTP for and uptake of eco-engineering projects. Furthermore, more cost-effective technologies and shared funding models may overcome existing financial impediments. We also found integrative legislation may be key to increased implementation of such NbS, given that existing policies were viewed as unsupportive.Read the free Plain Language Summary for this article on the Journal blog.