Seeds For Snapper Seagrass Restoration,
Adelaide, SA
OzFish has been leading the restoration of seagrass meadows along Adelaide’s metropolitan coastline since 2020. The meadows are an important nursery ground for snapper, calamari, whiting and blue swimmer crabs.
We are calling on recreational anglers, boaters, beachcombers, community organisations, and businesses to get involved. Register your interest for the 2025 Seeds for Snapper season today.
40,000 seeds dispersed
6,425 volunteer hours delivered
Since launching in South Australia in 2020, the scale of OzFish’s Seeds for Snapper achievements in the state has been impressive. Yet, there is still much work to be done to restore this important habitat.
The 2024 season of Seeds for Snapper in Adelaide is marks the fifth summer of the community-led seagrass restoration works. Fruits wash up in early December 2024, and processing days and other activities continue into 2025.
A massive 457 community volunteers contributed in the collection and distribution of 13,000 seeds during the 2023 Seeds For Snapper seagrass restoration initiative across six volunteer days.
With the help of more than 300 recreational fishers and local community members, OzFish has empowered Adelaideans to replant a record 15,000 seagrass seeds along its beaches as their annual Seeds For Snapper – Seagrass restoration project. During the month-long program
Seeds for Snapper returned for its second year in Adelaide and it built on the previous year’s success. More than 400 local recreational fishers, boaters, beachcombers, and members of the wider community combined to disperse over 15,000 seeds giving a massive 2,174 volunteer hours.
OzFish’s Seeds for Snapper initiative arrived in South Australia in 2020, following its success in Cockburn Sound, Western Australia. With more than 6,000 hectares of seagrass meadows lost from Adelaide’s metropolitan coastline, over a fifth of the city’s fishing grounds, the local fisheries ecology had been devastated.
Vital Marine Ecosystems
More than 6,000 hectares of seagrass meadows have been lost from Adelaide’s coastline, causing a hugely detrimental impact on local native fish populations.
As well as providing an important habitat for fish, seagrasses also help to stabilise soil and sediment on the ocean floor, helping to protect Australia’s shorelines from erosion and storms.
They also store carbon and nutrients, which helps to improve water quality and clarity – a hectare of seagrass stores 35 times more carbon than a hectare of rainforest.
A Helping Hand
Seagrass meadows are naturally slow spreaders and struggle in sandy habitats.
That’s why OzFish is giving the environment a helping hand to ensure seagrass seeds get to the right places and have the best chance of taking root and growing. This help will speed up the restoration of seagrass meadows and ensure it is where they’re needed.
Each year in in late November to early January, Posidonia seagrass produces a fruiting body that floats to the sea surface. Although thousands of these fruits are produced each season, many are washed onto the shore by wind and currents.
This means the seeds decay and do not contribute to seagrass regrowth.
Collected and processed
Many fruits are also swept far out to sea, where when the fruit opens, the seeds sink to the deep ocean floor where sunlight does not reach. Without sufficient light, these seeds also do not grow.
To address this challenge, OzFish mobilises beachcombers and boaters to collect the fruit they find – either washed ashore or floating on the ocean’s surface. Beachcombers collect the fruits and place them in a bucket with some water, while boaters bring the floating fruit in by dipnet – being careful not to catch other marine life by accident.
The fruits are then processed on shore in tanks, and the resulting seeds sewn into environmentally friendly biodegradable sandbags. These are then placed back in the ocean, at the correct depth, at identified locations.
Keeping your eyes open
The changeable nature of winds and currents mean that it’s not always known where and when seagrass fruits will wash ashore or be found on the ocean’s surface.
Quite often, they’ll just appear without any prior indication and that’s why the local community volunteer network is key to the success of seagrass restoration in South Australia.
When you register to be part of this year’s initiative, you’ll find out about how OzFish will spread the word to you and others when seagrass fruits are spotted in the local area.
So far, we’ve sewn over 40,000 seeds into 1800 sandbags and distributed them by boat to five different locations across Adelaide’s metropolitan coastline in Gulf St Vincent.
Frequently Asked Questions
Seagrasses are flowering plants that have evolved to live in marine environments. Seagrasses have root systems like land-based plants and that is one of the main ways that they differ from seaweeds or algae which do not have root systems. They grow like urban lawns, sending out runners or rhizomes to cover available space, forming large underwater meadows.
Seagrasses also produce flowers. The male flowers release pollen which fertilizes the female flowers. Once fertilized, the seed and fruit develop. Once mature, the fruit release from the flower head and float to the surface.
Floating fruit tend to be dispersed by the wind and currents until they split open, releasing the seed, which then sinks to the seafloor where it puts down roots. Research has shown that seeds are potentially an effective way of restoring many Australian seagrasses because we can collect large amounts efficiently, which can then be used to restore large areas.
Sometimes called ‘Strap-weed’ or ‘Ribbon-weed’, Posidonia australis is a large species of seagrass that has long, blade-like leaves and can grow up to 1m in length, but typically around 30-60 cm.
Posidonia australis forms a dense canopy that is important for sheltering many marine animals, particularly juvenile snapper, King George whiting and blue swimmer crabs.
Posidonia australis also plays host to a diverse range of small organisms called epiphytes (plants) and epifauna (animals) living in microhabitats and grazing on the leaves, stems and root systems.
These organisms are in themselves important contributors to the overall productivity of seagrass meadows and, due to their rapid growth, can be useful indicators of the nutrient loading in the water column. Even in a decomposing state, seagrass leaf litter (now known as detritus) comprises the main diet for many marine species.
It can form large, dense stands (called meadows), and is also often found mixed with other species of seagrass. The expansion of meadows of Posidonia australis occurs primarily by the lateral (sideways) growth of the rhizomes. Sexual reproduction is via the production of flowers (male and female reproductive organs on the same plant) that are pollinated underwater. Posidonia australis fruits in November to January in SA and the floating fruits are distributed by currents before splitting open to expose the seed.
A healthy fruit that has a seed inside is green/yellow in colour, and 1.5-2 centimetres in length. A fruit that has recently split open is still green/yellow and looks like a banana peel.
An old fruit that has split open will turn brown after 1-2 days in the sun.
Ideally, we want you to target fruit that is still intact (green/yellow and unsplit) and with the seed still inside.
If you have intact fruit mixed with a small amount of split fruit that is fine, there is no need to sort through it but please ensure the majority of your catch is not split fruit. If we collect too many fruit husks we risk having lots of fruit material but no seeds and this can be very time consuming to separate.
We would ideally like you to sort it and provide us with mainly fruit with seeds intact, but please limit your handling of the intact fruit.
Drop off locations, dates and times will be announced closer to the start of the Seeds for Snapper season.
Please also register as a Seeds for Snapper – Adelaide volunteer.
Yes. Click on the links to see the presentation from Project Scientific Leader Associate Professor Jason Tanner from SARDI Aquatic Sciences on his research in connection to this project.
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