Seagrass doesn’t get much love. It’s not charismatic like a whale or photogenic like a coral reef. It sits on the seafloor doing its job quietly - filtering water, stabilising sediment, feeding dugongs and turtles, providing nursery habitat for fish, and storing carbon at rates that put most terrestrial ecosystems to shame. And for decades, we’ve been destroying it at a remarkable pace.

Globally, seagrass meadows have declined by roughly 30% since the 1870s, with losses accelerating since the 1990s. Australia holds about 12% of the world’s seagrass, making it the country with the largest seagrass estate on Earth. And while Australia’s seagrasses are in better shape than those in many other regions, significant losses have occurred in areas like the west coast of Victoria, parts of the NSW coast, Moreton Bay in Queensland, and sections of the Western Australian coast.

The good news is that restoration is starting to work. After years of experimental approaches, several Australian projects are producing meaningful results. Here’s where things stand.

Why Seagrass Matters

Before getting into the restoration work, it’s worth understanding why seagrass loss is such a problem.

Carbon storage. Seagrass meadows are among the most efficient carbon sinks on the planet. Per unit area, they capture and store carbon at rates 35-40 times faster than tropical rainforests, according to research published by Deakin University’s Blue Carbon Lab. The carbon is stored not in the plant itself but in the sediment beneath, where it can remain locked away for millennia if the meadow remains intact.

When seagrass meadows are lost, the stored carbon is gradually released back into the atmosphere. A 2025 study estimated that global seagrass loss has released approximately 300 million tonnes of CO2 over the past century - roughly equivalent to the annual emissions of a mid-sized country.

Fisheries. Many commercially important fish species spend part of their life cycle in seagrass meadows. For some species, the relationship is critical: juvenile prawns, snapper, whiting, and bream all depend on seagrass as nursery habitat. The decline of seagrass has been linked to reduced catches of several inshore fisheries species along the Australian east coast.

Coastal protection. Seagrass meadows reduce wave energy and stabilise seafloor sediment. Their loss can increase coastal erosion and turbidity, which in turn can damage adjacent ecosystems like coral reefs by increasing sedimentation.

Biodiversity. Seagrass meadows support a remarkable diversity of life: over 100 species of fish, numerous invertebrates, and iconic megafauna including dugongs, green sea turtles, and seahorses. Shark Bay in Western Australia, home to the world’s largest seagrass meadow, supports one of the world’s most significant dugong populations.

What Caused the Decline

Seagrass loss in Australia has several causes, most of them related to water quality.

Nutrient runoff from agriculture and urban development causes algal blooms that block light from reaching the seagrass. Without enough light, seagrass can’t photosynthesise and dies. This has been the primary driver of seagrass loss in areas like Moreton Bay and the Tuggerah Lakes in NSW.

Coastal development - dredging, port construction, marina development, and stormwater outfalls - physically destroys seagrass and alters the sediment conditions it depends on.

Climate change is increasingly a factor. Marine heatwaves have caused seagrass die-offs, most notably in Shark Bay, where a severe heatwave in 2010-11 destroyed approximately 36% of the bay’s seagrass meadow - about 1,000 square kilometres. That single event released an estimated 9 million tonnes of CO2 from the disturbed sediment.

Boat mooring and anchoring causes localised but persistent damage. A single anchor drop can remove a patch of seagrass that takes years to recover naturally.

Restoration Projects That Are Working

Shark Bay, Western Australia. The massive die-off in 2010-11 prompted one of Australia’s largest seagrass monitoring and recovery programs. The good news from recent surveys is that natural recovery is occurring, though slowly. By 2025, approximately 60% of the lost area had regrown, with the remaining areas showing signs of recovery. Researchers from the University of Western Australia and CSIRO are monitoring the process and have identified that recovery is fastest where water quality and sediment conditions are most stable.

Botany Bay, New South Wales. A team from the University of New South Wales has been transplanting Posidonia australis (strapweed) into areas of Botany Bay where seagrass was historically present but had been lost due to urban runoff and port activities. The project, which began in 2020, has now established approximately 5 hectares of new seagrass beds using a combination of transplanted shoots and seed-based techniques. Survival rates have improved significantly as the team refined their methods - from about 30% in early trials to over 70% in recent plantings.

Adelaide’s Gulf St Vincent. One of the most ambitious seagrass restoration projects in Australia is underway in Adelaide’s metropolitan waters. The Seagrass Rehabilitation Program, run by the South Australian Research and Development Institute, has been working to restore Amphibolis antarctica (wire weed) and Posidonia species in areas damaged by nutrient pollution from Adelaide’s treated wastewater outfall. Improvements to the wastewater treatment plant have reduced nutrient loads, and natural recovery combined with active planting has restored significant areas.

Gladstone Harbour, Queensland. Following port expansion, a mandated offsets program required the restoration of seagrass habitat in Gladstone Harbour. While initial results were mixed, recent surveys show that restored areas are beginning to function as nursery habitat, with juvenile fish and prawn numbers increasing.

The Challenges

Seagrass restoration is harder than it looks, for several reasons.

Growth rates are slow. Many seagrass species grow only a few centimetres per year. Restoring a large meadow from transplants takes decades. This is fundamentally different from terrestrial reforestation, where fast-growing tree species can establish a canopy within 5-10 years.

Water quality must be good. You can’t successfully plant seagrass in water that has too much nutrient runoff, turbidity, or algal growth. Restoration only works if the underlying cause of decline has been addressed first. This often means costly upgrades to wastewater treatment, stormwater management, or agricultural runoff controls before planting can begin.

Scale is the challenge. Current restoration techniques work at the hectare scale, but losses have occurred at the hundreds-of-square-kilometres scale. Closing this gap requires more efficient planting techniques and, ideally, strategies that promote natural recovery rather than relying entirely on transplanting.

Monitoring is expensive. Tracking seagrass health underwater is time-consuming and requires specialised equipment and trained divers. Satellite monitoring can help at broad scales but can’t detect the small changes that matter for early-stage restoration assessment.

New Approaches

Several innovations are improving restoration prospects.

Seed-based restoration. Rather than transplanting adult shoots (which is labour-intensive and takes plants from existing meadows), researchers are developing seed collection and dispersal techniques. Seeds are collected during the natural fruiting season, processed, and either scattered over prepared sites or germinated in nurseries and transplanted as seedlings. This approach scales better than adult transplanting.

Drone monitoring. Aerial and underwater drones are making it cheaper and faster to survey seagrass extent and condition. High-resolution aerial imagery can map seagrass distribution over large areas, while underwater drones (ROVs) can inspect individual sites without the cost of diver surveys.

Citizen science. Programs like SeagrassSpotter engage recreational divers and snorkellers in documenting seagrass distribution and condition. This crowdsourced data supplements formal monitoring and helps identify areas of loss or recovery that might otherwise go unnoticed.

Blue carbon credits. There’s growing interest in using carbon credit markets to fund seagrass restoration. If seagrass meadows can generate verified carbon credits based on their carbon storage capacity, restoration projects become financially viable without relying entirely on government funding. Several pilot carbon credit projects are underway globally, and the Australian government has included blue carbon in its carbon crediting framework.

What You Can Do

Seagrass conservation isn’t glamorous, but it’s practical. If you boat in coastal waters, avoid anchoring in seagrass meadows - use moorings or sand patches instead. Support water quality improvements in your local catchment, since reducing nutrient runoff benefits seagrass even if the meadow is kilometres downstream. Report seagrass observations through citizen science platforms.

And pay attention to seagrass in conservation discussions. It deserves far more public awareness than it gets. This quiet, unglamorous ecosystem is doing extraordinary work - filtering water, storing carbon, feeding fisheries, protecting coastlines - and we’re only just starting to appreciate what we’ve lost and what it’ll take to get it back.