Saltmarsh survey to highlight changes

DIFFERENCE: A healthy saltmarsh community in 1995, left, with a 2020 photo, right, that shows mangroves invading the saltmarshes in the past 25 years. This indicates the area is experiencing increased tidal flooding. Photo: Supplied
DIFFERENCE: A healthy saltmarsh community in 1995, left, with a 2020 photo, right, that shows mangroves invading the saltmarshes in the past 25 years. This indicates the area is experiencing increased tidal flooding. Photo: Supplied

A survey undertaken by the Eyre Peninsula Landscape Board (EPLB) will discover how eastern Eyre Peninsula's threatened saltmarsh vegetation has changed over the past 25 years.

First established as four vegetation profiles in the mid to late 1990s, eastern Eyre Peninsula's saltmarsh ecosystems are prolific fish nurseries, essential sediment filters, provide a buffer against erosion and storm surge, and are home to many invertebrates and shorebirds.

The board will work in conjunction with the Department for Environment and Water (DEW) and University of Adelaide to re-survey these areas.

In 2013 the temperate coastal saltmarsh was listed as a vulnerable threatened ecological community under the Environmental Protection and Biodiversity Conservation (EPBC) Act.

"Since the initial surveys over 20 years ago, the saltmarsh systems are likely to have undergone change due to human influences and sea level rise," DEW coastal scientific officer Sharie Detmar said.

"Re-surveying will help identify changes to these vegetation communities. For example, it is likely these systems are moving further inland where there aren't barriers to movement - such as roads or levees.

"If we can understand how these systems are changing, it will help us decide the best ways to protect and manage them."

The survey is being undertaken as part of the Saltmarsh Threat Abatement and Recovery Project, and EPLB planning and assessment officer Andrew Freeman said he was excited that re-surveying would identify changes in habitat structure, condition and extent, plus provide information on the carbon content.

Saltmarshes are an important sequester of blue carbon, which is carbon captured by the world's ocean and coastal ecosystems.

"Healthy saltmarshes play an important role as carbon storage sinks, so it is crucial to continue monitoring these sites," he said.

"This re-survey will provide valuable information to inform priority conservation actions for the Eyre Peninsula's coastal saltmarshes."

Industry research fellow at the University of Adelaide Dr Alice Jones will lead sediment sampling to measure carbon content and changes in carbon storage over time.

Establishing this baseline data is a first for Eyre Peninsula and quantifying blue carbon stocks at selected sites could be extrapolated to other sites in the region through spatial modelling.

"Sediment sampling and modelling of the carbon content at sites on Eyre Peninsula will help identify long-term blue carbon sequestration sites, especially if management actions, such as improving hydrological flow, are implemented to improve the condition of saltmarsh which result in an increase in carbon storage," she said.

Seven other saltmarsh vegetation profiles along the western Eyre Peninsula coastline will be re-surveyed in the coming years.