Why this Cluster exists 

Climate change is exacerbating the frequency and magnitude of hazards such as erosion, fire and flooding along the highly dynamic coastal zone. Interactions between these and other climate change stressors, together with increasing human pressures, are threatening our unique and valuable coastal ecosystems such as coral reefs, seagrass meadows, coastal dunes, mangroves, wetlands and coastal forests. 

The Coastal Ecosystems Management research cluster focuses on nature-based solutions to build our understanding of the challenges facing coastal ecosystems, and developing solutions to address the negative impacts such as coastal hazards mitigation and blue carbon restoration.

The work undertaken aligns with and contributes toward UniSC’s research strengths and world rankings, particularly in SDG 13 Climate Action (1st in QLD THE Impact Rankings 2023), SDG 14 Life Below Water and SDG 15 Life on Land. 

The work of the Coastal Ecosystem Management cluster is driven by the expertise of the members, and the strength lies in the depth and breadth of knowledge that exists across the group.

• Associate Professor Javier Leon is a physical geographer with an established international leadership in scholarly activities with broad impact across coastal sciences. His research focuses on the innovative application of Earth Observation technologies, such as satellite imagery and drones, geospatial analysis and machine learning to improve the mapping and monitoring of coastal landforms and ecosystems.
• Dr Gareth Chalmers is an earth scientist, specialising in sedimentary geology and earth surface processes. Gareth is a leader in understanding the fate of organic carbon in sedimentary rocks and modern sediments. His research focuses on novel approaches to understand the complexity of carbon storage in sedimentary environments that encompass the subdisciplines of geochemistry, hydrology, geophysics and coastal sedimentary processes.
• Dr Luke Verstraten is an environmental scientist and engineer with a research focus on reducing the risk of flooding as well as the negative downstream effects of pollutants entrained in stormwater from construction sites and urban developments, both under current conditions and consideration of the impacts of climate change and urbanisation.
• Associate Professor Andrew Olds is an experienced marine ecologist with expertise in the fields of marine conservation, fisheries, spatial ecology and the impacts of global change on marine ecosystems. He has on-the-ground experience with conservation, fisheries and environmental management projects in tropical and subtropical estuaries and coastal waters, and has led multidisciplinary research teams in Australia and across the western Pacific.
• Associate Professor Ben Gilby is a marine ecologist with expertise in the fields of ecological restoration, conservation biology, fish biology and ecology, and fisheries. His research focuses on optimising the ways in which we manage, conserve, and restore ecosystems for greatest ecological, social and economic outcomes. Ben’s aim is to disentangle the multiple sources of ecosystem variability and disturbance, with a view to optimising ecosystem management, restoration and conservation in multiple settings.
• Dr Christopher Henderson is a marine ecologist with interests in the fields of spatial ecology, ecosystem functions and marine conservation prioritisation. His research focuses on marine protected areas, ecosystem functions, spatial ecology and fish ecology to determine best practices for management. Chris also has experience working with acoustic telemetry on fish and sharks in Australia and South Africa.
• Professor Catherine Yule multidisciplinary research focuses on the ecology of rivers, lakes and swamps, particularly subtropical and tropical peat swamps, extreme and endangered environments of global significance due to their vast carbon sequestration. Her pioneering research on tropical ecosystem functioning using microbial ecology, metagenomics and phytochemistry has provided new insights and overturned misconceptions, with important implications for conservation management and climate change mitigation.

Key achievements and impacts made by the Coastal Ecosystem Management cluster team cover the following themes:

• Mapping the distribution and ecology of unique South East Queensland regional fire adapted peatlands
• Shellfish reef restoration
• Coastal health monitoring
• Coastal erosion monitoring
• Measurement of carbon stock – Blue Heart project
• Integrated reef fish monitoring for the Great Barrier Reef
• Water quality improvement for estuarine developments

Turning a lost reef ecosystem into a national restoration program

Cluster member involved: Associate Professor Ben Gilby

Achieving a sustainable socio-ecological future now requires large-scale environmental repair actioned across legislative borders. Yet, enabling large-scale conservation is complicated by policy-making processes that grapple with a disconnect between socio-economic interests and political priorities, multiple sources of knowledge, and differing applications of policy.

In this paper, we describe how a multi-disciplinary approach to marine habitat restoration generated the scientific evidence-base, community support, and funding needed to begin the restoration of forgotten, functionally extinct shellfish reef ecosystems as a nationally actionable solution for improving marine biodiversity and productivity. This case shows that galvanising multi-sector support for widespread ecosystem repair can rapidly occur when socially-valued science acts upon political opportunities. We describe the key actors and actions undertaken to build a case for establishing Australia's largest marine restoration initiative. We review the complexities that led to state and national funding for reef restoration to meet sustainability goals, so that lessons can be disseminated and replicated elsewhere.

Attraction versus production in restoration: spatial and habitat effects of shellfish reefs for fish in coastal seascapes

Cluster members involved: Associate Professor Ben Gilby, Associate Professor Andrew Olds, Dr Christopher Henderson

Restored shellfish reefs provide valuable habitat for fish, but it is not clear how different approaches affect performance, and either promote the development of new fish populations (i.e. ‘production’) or simply attract individuals from the broader seascape (i.e. ‘attraction’). We measured the effects of a 1.5 ha shellfish reef restoration site on fish assemblages in Pumicestone Passage in eastern Australia, which contains replicates of six different restoration units: shell patch reefs, crates of shells, and biodegradable matrix, and each had replicates with and without live oysters. Fish were surveyed before restoration and then every 6 months for 30 months with baited (at restoration and control sites) and unbaited (at 106 sites across the seascape to detect potential fish attraction, and at the different restoration units) underwater cameras.

Shellfish reef restoration represents an addition to the carrying capacity of Pumicestone Passage for fish for two key reasons. Firstly, restoration significantly enhanced the diversity and abundance of fish assemblages and the density of harvestable fish at the restoration site by 3.8, 10.7 and 16.4 times, respectively. Secondly, fish distributions across the broader seascape did not change in response to succession at the restoration site. Fish assemblages did not differ between restoration units or the presence or absence of oysters. These findings further support the notion that restored shellfish reefs significantly enhance fish abundance and diversity and that restored reefs can enhance the overall carrying capacity of seascapes for fish, rather than simply centralising them at restoration sites.

Coastal change along Noosa, Australia during a triple back-to-back La Nina (2020-2023)

Cluster member involved: Associate Professor Javier Leon

The capacity of sandy beaches to provide coastal protection varies across time and space. Recent research suggests climate change could result in substantial erosion of most sandy beaches by the end of the century, with significant social and economic impacts. Furthermore, storm clusters and cyclone events generate extreme erosion of sandy beaches which are not fully recovered. Three back-to-back La Nina events occurred between 2020-2023. La Niña is associated with warmer waters in the western Pacific Ocean, which increase storminess off Australia's east coast. Chances of a higher number of tropical cyclones increase, as do the chances of cyclones travelling further south and more frequent passages of east coast lows.

The aim of this study is to present preliminary coastal change observations along the Noosa coast, Queensland, Australia during this rare, but not unprecedented, period. Detailed (3 cm spatial resolution) and frequent (monthly) drone-derived subaerial beach volumetric surveys were undertaken along six wave-dominated sandy beaches. The frequency of coastal storms considerably increased between an average 7.2 storms/yr during 2015-2020 and 12.6 storms/yr during the 2020-2023 triple La Nina period. Even though storms were generally less energetic during La Nina period, average duration was longer. Building an understanding of coastal response to both gradual and extreme events is especially critical in an era of progressively rising sea levels which are likely to exacerbate already existing trends.

*This study is yet to be published.

Rapid plant responses following relocation of a constructed floating wetland from a construction site into an urban stormwater retention pond

Cluster member involved: Professor Catherine Yule

This study compared plant growth, nutrient partitioning and total nutrient uptake by tall sedge (Carex appressa) plants in large-scale Constructed Floating Wetlands (CFWs). Two CFWs with a total area of 2088 m2 were installed in a 2.6 ha man-made urban lake to treat stormwater runoff during the construction phase of a 45-ha residential development. After 12 months of operation, parts of the CFWs, with a total area of 147 m2, were removed from the urban lake and relocated into a well-established 0.127-ha stormwater retention pond at another site. Biomass and nutrient concentrations of C. appressa shoots above the floating mat and roots below the mat were analysed at both sites 12, 16 and 25 months after initial planting. Plants at the urban lake maintained an extensive root network but there was no increase in total plant biomass at 16 and 25 months after planting. In contrast, the relocated plants in the stormwater pond showed extensive shoot growth but a significant decline in root biomass.

This study demonstrated that C. appressa adapted rapidly to changes in nutrient availability. The implications are interesting as nutrient levels can be low in constructed lakes during the initial phase of urban developments but can increase rapidly as the development progresses. The study demonstrated multiple benefits of CFWs for stormwater treatment during the early construction stages of an urban development and the potential benefits of relocating and establishing CFWs in existing stormwater retention ponds and lakes.

Dredging fundamentally reshapes the ecological significance of 3D terrain features for fish in estuarine seascapes

Cluster members involved: Dr Christopher Henderson, Associate Professor Ben Gilby, Associate Professor Andrew Olds

Landscape modification alters the condition of ecosystems and the structure of terrain, with widespread impacts on biodiversity and ecosystem functioning. Seafloor dredging impacts a diversity of flora and fauna in many coastal landscapes, and these processes also transform three-dimensional terrain features. The potential ecological significance of these terrain changes in urban seascapes has, however, not been investigated.

Method: We examined the effects of terrain variation on fish assemblages in 29 estuaries in eastern Australia, and tested whether dredging changes how fish associate with terrain features.

Conclusions: Contrasting fish-terrain relationships highlight previously unrecognised ecological impacts of dredging, but indicate that plasticity in terrain use might be characteristic of assemblages in urban landscapes. Incorporating terrain features into spatial conservation planning might help to improve management outcomes, but we suggest that different approaches would be needed in natural and modified landscapes.

Sensitivity of Australian roof drainage structures to design rainfall variability and climatic change

Cluster member involved: Dr Luke Verstraten

The main design determinant for small catchment hydraulic structures is rainfall intensity. Localised relationships between rainfall intensity, frequency and duration (IFD) are used to design each structure to a specified level of performance. However, limitations in rainfall observations introduce uncertainty in IFD values. Further, this uncertainty is compounded by changes in climatic conditions via anthropogenic forcing. Whether this is a cause for concern depends on the structure's sensitivity to deviations away from design rainfall values.

Here, we investigate the ability of roof drainage systems to accommodate deviations in design rainfall. We assess the sensitivity of box gutter overflow designs across Australia to spatial variability in IFD values, and projections of IFD values due to climatic change. Different overflow designs were found to have markedly variable responses to rainfall intensity increases, from 13% to 406% before failure. Potential increases in rainfall intensity from spatial variability uncertainty varied from 2 to 54%. While rainfall projections for the 2090 decade ranged from −15 to +59%. Rainfall intensity increases as high as 259% were noted when both sources of uncertainty were combined for a temperature rise scenario of 5 °C. At the majority of locations coupled increases in rainfall intensity were primarily driven by existing rather than future uncertainties for a 2 °C temperature rise scenario. Considering design rainfall uncertainties in terms of design sensitivity shows that adapting to present and future uncertainties can come at no additional cost for some design options while other options need to be altered to reduce the risk of failure.

Coastal wetland rehabilitation protects Sunshine Coast lowlands from sea level rise (Blue Heart Project)

Cluster member involved: Dr Gareth Chalmers

Coastal wetlands, particularly mangrove wetlands, have the unique ability to accumulate both organic and inorganic sediment at rates that can keep pace with accelerating sea level rise. At the same time, these coastal wetlands store some of the highest carbon concentrations (referred to as blue carbon) compared to other ecosystems. This study is a collaboration between UniSC and Sunshine Coast Council that has implemented one of the largest rehabilitation projects (Blue Heart Project) to protect lowlands between Coolum and Yandina.

Last century, the area was reclaimed for sugar cane farming by constructing a series of drainage canals and tidal locks. However, the tidal lock system has been neglected and tidal influence has been increasing over the last couple of decades. Majority of the lowlands is less than 1 m above sea level with some areas currently below sea level (-0.25 m). The area is at risk of being permanently flooded and land would be lost if rehabilitation is not conducted.

This research project is measuring the changes to the lowlands over time, at a millimetre scale, to determine the rate sediment accumulates to compare to the local sea level change (global models predict 80 cm of sea level rise in next 80 years). The project will determine if the rehabilitation area can continue to naturally build up and keep pace with current sea level rise (preliminary results show that it can). The project will also investigate how much carbon is being stored in the area by comparing the soil profile before and after rehabilitation.

The blue heart project is an exemplar to other governments on how to protect coastal environments that are under threat by climate change and also be part of the climate change mitigation strategy.

Contact: Dr Javier Leon