Eco-engineering and Restoration of Coastal Habitats in Australia, Summaries of Law

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Eco-engineering and restoration

of coastal habitats in Australia

A shellfish reef breakwater for erosion control at Portarlington, Port Phillip Bay (Image: Ralph Roob)

Globally, coastal

habitats that include

saltmarsh, mangroves,

seagrass, shellfish and

coral reefs have

suffered significant

declines.

This decline in

coastal habitats results

in a loss of important

ecosystem services, such

as biodiversity provision,

water purification, carbon

filtration and coastal

defence.

Nature-based coastal

defence is the creation

or restoration of coastal

habitats through hybrid and

soft ecological engineering

to recover shoreline

protection services along

with other ecosystem

services.

> > > Nature-based coastal defence is also referred to as ‘nature-based features’ or ‘living shorelines’ in the United States, or ‘building with nature’ in Europe.

Climate change is increasing

the risk of erosion and flooding

through drivers that include

accelerating sea level rise,

changing wave climate, and

potentially more frequent storm

events. Coupled with this

changing climate is an increase

in global population along

the coast, which will increase

exposure of people to existing

and future coastal hazards.

Climate change and coastal

urbanisation is therefore driving

an increased need for investment

in coastal defence infrastructure

to protect coastal assets.

Artificial structures, such as

seawalls and breakwaters, are

commonly used for coastal

protection. These coastal defence

structures result in a loss of

native biodiversity as they replace

natural shorelines with a lower-

quality habitat for marine species.

In addition to the ecological

impacts, these structures are

non-adaptive as they must be

rebuilt, upgraded and maintained

in response to a changing climate

at a significant economic cost.

Researchers at the National

Centre for Coasts and Climate

(NCCC) in the Earth Systems

and Climate Change Hub are

working on ways to develop more

sustainable and adaptive methods

to protect the coast through

applying nature-based solutions

to build more climate resilient

coastal communities.

In some parts of Europe and the United States, nature-based coastal defence is increasingly being used in a variety of environmental conditions. For instance, in Chesapeake Bay, Virginia and Maryland, USA, soft (e.g., restored saltmarsh) and hybrid (e.g., saltmarsh with rock sills) eco-engineering techniques are used in low- to mid-energy wave conditions, respectively. Sand nourishment is used in the Netherlands to preserve beaches and dunes for protection in higher energy wave conditions. These nature-based techniques are supported by state and national policies. Despite international precedence for the development of nature-based solutions as a cost-effective and sustainable approach to shoreline protection from erosion and flooding, they are not widely used in Australia, except for beach nourishment. Key to their wider implementation is: (1) improved scientific knowledge; (2) effective governance; and (3) socio- economic acceptance. Oyster reef living shoreline using bagged shell in Virginia, US. Developing a nature-based coastal defence strategy in Australia We are working towards achieving this through the implementation of on- ground case studies to inform coastal management and government policy.

Custom-designed mangrove planters are being trialled in conjunction with mangrove plantings to provide erosion control in Altona, Grantville and Lang Lang in Port Phillip Bay and Western Port Bay. The mangrove planters are designed to improve the establishment of planted mangroves by reducing wave energy while the juvenile plants grow. We are monitoring these planters to measure the success of these structures in enhancing mangrove survival, reducing significant wave height and reducing shoreline erosion. Testing hard ecological engineering In heavily modified or wave exposed areas, soft and hybrid solutions for coastal protection may not be feasible. In these circumstances, hard ecological- engineering techniques can be applied to improve the ecological value of new or existing artificial structures. In this project, we are trialling a range of methods for growing mussels on pier pilings, pontoons and breakwaters in Wyndham Harbour, Port Phillip Bay. These artificial structures replace natural habitat in the bay and are hotspots for invasive species. This project will measure the effectiveness of these mussels in preventing colonisation of invasive species, and improving native biodiversity and water quality Effects of seeding mussels in improving ecological functioning of harbours. in Wyndham Harbour, Victoria. (Data from Adams et al. The University of Melbourne/Wyndham Harbour). Globally, there is a lot of interest in developing nature-based coastal defence approaches for coastal protection. In Victoria, surveys have demonstrated that most coastal residents have observed Mangrove pods for erosion control at Grantville, Victoria. flooded (77%) and eroded (68%) areas in Port Phillip and Western Port bays. A similar proportion of individuals (65- 77%) think that natural vegetated habitats, hybrid approaches (mangroves with pods and breakwaters with mussels) and artificial structures provide an important role in coastal protection. Our ongoing work is seeking to assess the cost-benefits of nature-based coastal defence relative to artificial structures for coastal protection. Developing nature- based coastal defence guidelines NCCC researchers in the Earth Systems and Climate Change Hub are currently working to use current and previous knowledge to develop industry-accredited guidelines for the wider application of nature-based coastal defence in Australia. This research involves an interdisciplinary team of ecologists, engineers, social scientists, industrial designers, coastal managers and policy makers. Hybrid mangroves

• Morris RL, Graham TDJ, Kelvin J, Ghisalberti M, Swearer SE. In press. Kelp beds as coastal protection: wave attenuation of Ecklonia radiata in a shallow coastal bay. Annals of Botany.
• Morris RL, Konlechner TM, Ghisalberti M, Swearer SE. 2018. From grey to green: efficacy of eco-engineering solutions for nature-based coastal defence. Global Change Biology 24, 1827-1842.
• Morris RL, Bilkovic DM, Boswell MK, Bushek D, Cebrian J, Goff J et al. 2019. The application of oyster reefs in shoreline protection: are we over‐engineering for an ecosystem engineer? Journal of Applied Ecology 56, 1703-1711.
• Strain EMA, Morris RL, Bishop MJ, Tanner E, Steinberg P, Swearer SE et al. 2019a. Building blue infrastructure: assessing the key environmental issues and priority areas for ecological engineering initiatives in Australia’s metropolitan embayments. Journal of Environmental Management 230, 488-496.
• Morris RL, Strain EMA, Konlechner TM, Fest BJ, Kennedy DM, Arndt SK, Swearer SE. 2019. Developing a nature-based coastal defence strategy for Australia. Australian Journal of Civil Engineering 17 (2), 167-176. Further information Socio-economic considerations The Earth Systems and Climate Change Hub is funded by the Australian Government’s National Environmental Science Program. For more information please contact: Professor Stephen Swearer [email protected] nccc.edu.au