Tinchi Tamba wetlands
Photo © Julian O’Mara

Intertidal wetlands and the impact of sea level rise in south-east Queensland

Julian O’Mara, School of Biology, University of Queensland

Julian O'Mara

Intertidal wetlands provide a range of ecosystem services including the provision of fish and bird habitat, coastal protection and nutrient and carbon sequestration and cycling. Commercial and recreational fish species are highly dependent on intertidal wetlands with fish catches correlated with the area of mangroves and saltmarsh over a wide range of locations, including south-east Queensland. Worldwide intertidal wetlands ecosystems are threatened by urban development, aquaculture, mining and overexploitation of resources. Of increasing interest is the threat posed by sea level rise (SLR). Intertidal wetlands habitats are strongly influenced by SLR, which can result in changes in their distribution and composition. These physical changes in vegetation are likely to impact critical fish habitat created by intertidal wetlands.

The aim of my study is to enhance the understanding of how SLR will effect the distribution of intertidal wetland vegetation and their role as fish habitat in Moreton Bay. Identification of how these environments may change as a result of SLR will allow for comprehensive environmental planning, ensuring that these valuable habitats remain for future generations.

North Moreton Bay
Photo © Julian O’Mara

My honours project uses a number of approaches to gain a greater understanding of how SLR will affect intertidal wetlands and fish habitat.  These include:

• Modelling changes in the extent of intertidal wetlands using the Sea Level Affects Marshes Model (SLAMM), which incorporates complex processes that occur, including wetland accretion (gain in volume of soils) and landward migration when intertidal wetlands are influenced by long-term SLR. The model enables predictions of change in composition and distribution of intertidal wetland vegetation towards the year 2100.

• Analysis of spatial metrics that define the quality of the wetlands as fish habitats to infer how changes in intertidal wetlands will impact upon fish habitats in the future. In particular, changes in the area of wetland, mangrove perimeter and distance to other known fish habitat (e.g. seagrass) will be measured.

Preliminary results have shown that changes in intertidal wetland vegetation are dependant on the magnitude of sea level rise. The rate of change in wetlands increases rapidly after the year 2050. This may indicate that we have a small window of opportunity to plan for adaptation to sea level rise in a way that maintains wetland areas and high quality fisheries habitat.

Tinchi Tamba wetlands
Photo © Julian O’Mara

The findings of my research are being used by Fisheries Queensland in a project that aims to increase the protection of intertidal wetland and subsequently fish habitat in the face of climate change. In addition the National Climate Change Adaptation Research Facility has in part funded this project and may use the outcomes to inform the National Climate Change Adaptation Research Plan.

I would also like to thank the Goodman Foundation for the funds they have provided for this project and finally thanks to Wildlife Queensland for their financial support.