Research

The challenge

Coastlines in the Pacific are under a variety of pressures. Sea level rise is squeezing coastal defences and land-use practices have cleared 1000s of hectares of mangroves—nature’s primary defence. In urban locations, new marinas and port expansions have seen mangroves replaced with concrete or rock walls.

In Pacific communities, mangrove loss has had severe environmental, economic and social impacts.

Some of these include: increased flooding and coastal erosion risk, reduced carbon sequestration, declining marine and estuarine water quality, reduced biodiversity, decreased sustainable fishing yields, declining seagrass and coral reef ecosystems, declining crop yields, decreasing farming profitability, economic impacts on tourism, loss of livelihoods, reduced fuel and wood products, reduced supply of traditional foods and medicine, loss of social and cultural heritage, reduced recreation, and community impacts to health, wellbeing and education.

The solutions

In partnership with local communities and government agencies, researchers from UNSW Sydney and the University of the South Pacific (USP) are piloting two emerging nature-based solutions in Fiji. Originally developed at UNSW, these innovative, evidence-based interventions are designed to benefit both people and the environment.

Solution 1: Restoring the tide

We’re restoring mangrove ecosystems by addressing one of the root causes of their decline: disrupted tidal flows. Instead of supporting large-scale, labour-intensive mangrove planting, which is often unsustainable, we’re investigating how best to recreate the conditions for mangroves to regenerate naturally. This novel approach has the best chance of success in areas where natural hydrological processes have been altered, but mangrove seeds remain present in the environment.

We’re working closely with communities and government agencies to explore several potential restoration sites in Fiji. Our researchers are carrying out detailed field investigations and collecting a variety of data to understand how decades of drainage and land-use change have affected coastal landscapes. At the same time, we’re learning from communities about what’s important to them, and how potential changes in tidal flows may impact their lives now and in the future. Together, this evidence is informing the design of site-specific tidal restoration approaches.

Solution 2: Floating forests

Our floating mangrove pontoons are designed to integrate the many benefits of mangroves into maritime infrastructure, rejuvenating coastal spaces that support tourism and other industries. Drawing water from the sea below, these ‘floating forests’ help to improve water quality, absorb harmful wave energy, sequester carbon and provide habitat in highly urbanised areas.

The Project Halo team has designed three prototype pontoon systems and deployed hundreds of mangrove seedlings at a trial site in Sydney, Australia. We’re monitoring how the platforms perform under real environmental conditions, tracking seedling survival and growth and measuring the conditions around the pontoons to determine the most effective design. The floating pontoons will then be deployed at a second trial site in Fiji, where we will test them under tropical Pacific conditions and alongside our tidal restoration activities.

The novel nature-based solution to integrate the benefits of mangroves into maritime infrastructure is based on techniques developed in partnership with UNESCO in wave flumes at UNSW Water Research Laboratory.

The impacts

Over five years, researchers will work with local partners to closely track the environmental, social, and economic outcomes of Project Halo in Fiji.

Our expected impacts extend beyond immediate environmental gains to long-term outcomes that position Fiji at the forefront of innovative approaches to climate resilience.

• Increases in healthy mangrove habitats
• Improved marine and estuarine water quality
• Increased biodiversity levels
• Enhanced carbon sequestration
• Improved shoreline protection
• Increased community collaboration across climate change adaptation activities
• Community empowerment and cultural enrichment through the integration of traditional knowledge.
• Diversified household income from blue carbon farming
• Increased food and energy security
• Higher family and community incomes supporting better livelihoods
• Increased trust from all sectors in nature-based economic solutions
• Increased environmental science and engineering workforce capacity
• Growth in local tourism opportunities
• Opportunities for future collaborative research
• Better progress towards the United Nations Sustainable Development Goals and the 2021-2030 Decade of Ecosystem Restoration.