Seagrass Trials

In reply to the Hon. T.A. FRANKS ().18 June 2025).

The Hon. C.M. SCRIVEN (Minister for Primary Industries and Regional Development, Minister for Forest Industries): I am advised:

That SARDI has recently undertaken a three-year seagrass restoration project off Port Gawler with the assistance of the University of Adelaide, and funded by the Commonwealth Department of Climate Change, Energy, the Environment and Water through 1 of 5 Blue Carbon Ecosystem Restoration grants awarded nationally.

During this project, 100,000 hessian sandbags were deployed in May/June 2023 and 2024 to provide stable substrate for naturally present seagrass seedlings (wireweed) to attach to and gain a foothold that helps them to withstand winter storms. A further 5,000 bags were deployed in January 2024 and 2025 with seedlings of another species (strapweed) planted into them. The sandbags were deployed over 14 hectares. Few seedlings attached in the winter of 2023, with higher numbers attaching in 2024.

While the remaining seedlings have shown good growth, it is expected to be around a decade before the site returns to a natural looking seagrass meadow, as this requires the seagrasses to mature and send out runners to colonise bare sand in between the bags. The biodegradable bags will rot away within two years, but by this time the seedlings should be large enough to survive on their own.

In addition to seedlings on the bags, summer 2025 was an exceptional year for natural settlement of strapweed seedlings into both the restored area and nearby bare sand, with the presence of bags doubling the number of seedlings settling into adjacent bare sand. A detailed report is currently being produced and will be made available on the PIRSA website once completed.