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Geographe Bay seagrass shows resilience

Scientists monitoring the health of Geographe Bay’s seagrass meadows continue to be pleased with the overall health of the seagrass following the release of the 2022 Keep Watch seagrass monitoring report by GeoCatch.

Each summer, scientists from Edith Cowan University join divers from the Department of Biodiversity, Conservation and Attractions to monitor the seagrass meadows at eight sites across Geographe Bay.

Associate Professor Kathryn McMahon from Edith Cowan University says 2022 was the 11th year that scientists have monitored the meadows and they have identified no major concerns regarding seagrass health.

“This year we had no major concerns and we were pleased to see significant increases in shoot density in the centre of the bay near the Vasse Diversion Drain and Busselton Jetty” said Associate Professor McMahon.

“Compared to other seagrass meadows in the state, all monitoring sites in Geographe Bay are well above the minimum average site shoot density for Posidonia sinuosa, highlighting the value of this ecosystem”.

The monitoring program uses triggers to monitor health over time. In 2021, five sites saw declines in shoot density with two sites declining more than 20% at Vasse Diversion and Forrest Beach, however in 2022 this was reversed and these sites had the greatest increases.

“The other good news for Geographe Bay is that average shoot densities here are higher than the maximum averages for sites in Perth and Jurien waters. This indicates that human activities and ocean warming is not currently impacting meadows here as is observed further north”.

GeoCatch coordinates the program to track any potential impacts from nutrients entering Geographe Bay from waterways and drains. The program is made possible through funding from the Water Corporation and support from DBCA with boats, scientists and rangers assisting with monitoring.

Annual monitoring will occur again in February 2023.

The 2022 Keep Watch seagrass report can be found on the Revitalising Geographe Waterways website.

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