In this episode of OzCast, Jason Tanner dives beneath the surface of South Australian waters to unveil how he is working to "green the blue" by dropping sandbags in strategic areas to bring back the lost seagrass meadows of yesteryear. After spending over 25 years developing this technique from the ground up, he explains how his work went from an idea to a now industrial-level program that sees tens of thousands of bags being deployed every year.  

Jason has 30 years' experience overall in marine ecology, working in tropical and temperate systems. He has published over 80 papers, most in high-profile international journals, and numerous reports. He undertakes field and laboratory studies of marine ecosystems and also has a strong grounding in statistics and mathematical modelling. 

His first exposure to seagrass was as a teenager snorkelling in the coastal lakes of southern NSW, although it would be many years before he would return to them, taking a detour via the coral reefs of the Great Barrier Reef in between.   

This detour involved a PhD and postdoctoral studies on corals at Heron Island, before moving to the South Australian Research and Development Institute to study the impacts of prawn trawling on the seafloor.  From here he became interested in the way fragmentation of seagrass habitats influenced the fauna that lived in them, which then progressed to an interest in the seagrasses themselves and how to reverse the extensive habitat loss seen along the Adelaide coast (and elsewhere).  

Throughout the episode, Jason explains that this interest led him to develop novel low-cost techniques for seagrass restoration tailored to the main species found in South Australia.  His hessian sandbag technique can be deployed for 5-10% of the cost of traditional transplantation involving divers and doesn't require the removal of seagrass from a donor meadow.   

Instead, it relies on providing a firm substrate for naturally present seedlings to attach to (for wireweed - Amphibolis) or collecting beachcast fruits that would otherwise dehydrate and be lost (for strapweed – Posidonia australis).  He is now in the process of establishing a 20-hectare restoration plot just north of Adelaide, funded by the Commonwealth Government, which will be the largest single seagrass restoration in Australia.  

Jason offers a wealth of information on how programs like this develop and transform, to the point where he is now dropping over 25,000 bags in a single deployment. 

 Having spent countless hours researching seagrass, Jason highlights the impacts that seagrass has faced on the South Australia me