Persistence study: Propagules and juvenile mangroves, St Kilda boardwalk
February 7, 2023
Tours and Field trips
March 29, 2023
Since 2018, ECF volunteer Steve Papp and Catherine McMahon (and other volunteers) have been monitoring Zostera along the western shoreline of Torrens Island.
On Monday February 27th, Steve and Catherine anticipated showing Urrbrae TAFE students how that monitoring is done, at sites just to the north and south of the old Torrens Island jetty.
However our plans were in vain, because sadly the 3 day heatwave from Feb 22nd to 24th (temperatures at or above 40 degrees) coincided with very low tides (around 0.2m) in the middle of the day and the seagrass was either dead or looked like it had had a buzz cut. This was completely unprecedented in ECF visits to Torrens Island and very concerning, including as to what the future will hold for the Zostera with hotter weather due to climate change.
It has been wonderful to observe the spread of Zostera, heading south along the Torrens Island shoreline, and to know the many benefits it brings. ECF has for several years been giving guest lectures to Urrbrae TAFE students that highlight the importance of seagrass – Seagrass is Awesome – and their presence and monitoring along Torrens Island.
Zostera dead or buzzcut
Zostera stem & roots
Assoc Professor Jason Tanner, SARDI visited Torrens Island with Catherine on March 9th, with that visit confirming dead seagrass north and south of the jetty, and at two sites further south on Torrens Island, including a trial restoration site. Jason walked to the water’s edge and saw living seagrass underwater.
Scorched seagrass, north of Torrens Island jetty
Jason Tanner at water’s edge, past dead seagrass
Steve Papp, on a bird monitoring visit to Section Bank (at Outer Harbour) also found that the seagrass there had been affected, except in a number of tidal pools (around 50cm deep at low tide) which still have healthy seagrass growing.
Section Bank seagrass, March 2023. Photo by Steve Papp
Catherine and Steve will return to Torrens Island in early April to check for any signs of living seagrass, but will then need to wait until October for the return of daytime low tides to check on the extent of recovery.
