Scoping for an Australian Wetland Inventory: identifying knowledge gaps and solutions for mapping Australian marine and coastal wetlands

Like many wetlands around the world, however, Australian wetlands continue to be threatened, degraded, and lost due to climate change, development, and other human activities. A national wetland inventory is being developed by the Australian Government as a step towards improving wetlands management and protection, and fulfilling national and international reporting requirements.

This Marine and Coastal Hub project provided a consolidated overview of coastal wetland mapping to determine future research and mapping priorities for developing this part of the national inventory.

Approach and findings

The project team assessed five critical aspects of coastal wetland inventory: seagrasses, saltmarshes, intertidal macroalgae, shorebird habitat, and blue carbon mapping. A combination of literature assessments and interviews with 73 key end-users and industry representatives generated 25 recommendations across the five areas of interest. The recommendations were summarised in three sections according to: high demand from end-users, identified fundamental practices, and the critical aspects listed above. The project outcomes reflect a strongly collaborative approach partnering with practitioners and scientists from all Australian states and territories.

Recommendations in response to high demand from end-users

Overall strategy: Host a project that develops a national approach to mapping and classifying key attributes of coastal wetlands.

• Seagrass: improve capacity for mapping subtidal seagrass to fill notable inventory gaps in deep waters across Australia and in turbid waters in northern Australia.
• Saltmarsh: identify and actively manage retreat of coastal saltmarsh and encroachment of mangroves.
• Intertidal macroalgae: conduct widespread mapping of intertidal macroalgae.
• Shorebirds: produce maps that integrate existing habitat zones and threats to shorebird habitat, including sea level rise, mangrove encroachment, and development.
• Blue carbon: Maps should include different habitats to demonstrate connectivity across the seascape and be integrated with national products.

Specific recommendations for seagrass, saltmarsh, macroalgae, shorebirds and blue carbon

Seagrass

• Map deep seagrasses.
• Map subtidal seagrasses Australia-wide (notable gaps exist in northern Australia and parts of Western Australia).
• Develop a consistent method to classify seagrass meadow characteristics, particularly meadow condition, transience, and species or structural composition, to include in national maps.
• Increased use of rapid underwater imaging technology and automated image processing to increase mapping coverage at decreased costs.
• Strategically select regions for seagrass mapping using fauna species distribution models, knowledge of Traditional Custodians, and bathymetry.

Saltmarsh

• Promote access to high quality satellite imagery for more accurate saltmarsh mapping.
• Produce maps with clear differentiation of saltmarsh and mangroves for management of mangrove encroachment and blue carbon resources.
• Improve the technology for mapping saltmarsh using unmanned aerial vehicles.
• Include habitat condition and species composition in saltmarsh maps.
• Intertidal macroalgae
• Produce high quality maps of intertidal macroalgae in Australia.
• Invest in remote sensing methods to simultaneously map macroalgae extent, dominant species, and sediment composition of the intertidal space.
• Map historical macroalgae extent using satellite image archive.
• Identify any climate change induced distribution shifts for macroalgal species and establish the ecological impacts of these contractions.

Shorebirds

• Develop predictive maps demonstrating the impacts of sea level rise, mangrove encroachment, development, and climate change on shorebird habitat to determine opportunities for mitigation.
• Improve maps of shorebird habitat, with emphasis on tidal mudflats and understudied regions.
• Map the supratidal clay pans used by shorebirds in high tides as shorebird habitat.
• Monitor prey density and availability at key shorebird sites.

Blue carbon

• Produce and integrate maps of blue carbon habitats below the highest astronomical tide into one resource.
• Produce historical maps of blue carbon systems, including maps of pre-clearance vegetation.
• Field verification for blue carbon stock maps, including strategic sampling in various geomorphological settings.
• Carefully measure and map co-benefits to understand full value of restoration projects.
• Models of climate change induced landward migration of coastal ecosystems, including artificial barriers, are needed to assess changes in blue carbon stocks and sequestration due to sea level rise.

Outcomes

This project provided a consolidated assessment of coastal wetland mapping. Recommendations for future research and mapping priorities included data management practices to effectively harness and share existing knowledge. Future mapping efforts can then be integrated and interrogated on a national platform, and will remain relevant for future national applications such as ecosystem accounting. Equipped with this information and advice, the Australian Department of Climate Change, Energy, the Environment and Water is better positioned to develop an Australian Wetland Inventory.

Project location

National