A key signifier of a healthy marine ecosystem, seagrass, has returned to many areas of Quandamooka (Moreton Bay) thanks to combined efforts and long-term targeted investments in catchments across South East Queensland.

There has been significant long-term recovery of seagrass in southern Deception Bay which was lost entirely in 1996. Seagrass meadows in Bramble Bay, which have not been seen since the 1970s, have also recovered over the past two years and are now widespread in waters off the southern Redcliffe Peninsula.

Seagrass slowly recovering in Moreton Bay.

These improvements in the bay’s ecological condition, are likely a result of a reduction in nutrient loads to the bay over an extended period.

While in part a factor of prolonged drought during which time fewer sediments and pollutants are pushed out to the bay, the recovery, and rejuvenation of seagrass shows that the bay has resilience and can recover.

Bringing back seagrass has been attempted in other parts of the world, such as Denmark, without success. This suggests that Quandamooka had not gone beyond a point of no return when large investments were made to protect the bay and restore lost seagrass meadows 20 years ago.

The impact of floods on seagrass

Mud dumped in the shallower regions of the bay by previous floods has been redistributed to deep areas in Central Bay or removed from the bay entirely. This has improved the water quality of the bay over the last five years.

Unfortunately, sediment flushes out into Quandamooka from the region’s rivers and estuaries, continues to smother seagrass, and causes poor water quality. Most of the mud enters our waterways during large flood events, such as those experienced in 2011, 2013, and 2017.

Suspended sediment particles and phytoplankton in the water post-flood events, result in the water looking cloudy or dirty. This is especially important for benthic habitats because it impacts the amount of light reaching the seafloor. As a result, key habitats like seagrass and corals can become smothered and key processes such as reproduction and growth are inhibited.

Trees Regenerating Land and Productivity | Scenic Rim Regional Council

A property in Bromelton is embracing regenerative land management practices by enhancing the long-term sustainability of the enterprise with improved productivity and local biodiversity. Incorporating vegetation in key locations seeks to reduce the loss of topsoil while improving the local amenity values, creating wildlife corridors, and acting as a refuge for stock during extreme weather events like prolonged drought and heat waves.

Learn more here: https://hlw.org.au/download/trees-regenerating-land-and-productivity/

Healthy Catchments | Healthy Land & Water and the Department of Environment and Science

The Healthy Catchments program delivers stream bank and gully stabilisation projects in areas identified as contributing high sediment loads to Ramsar-listed Moreton Bay.

Gully and streambank projects control erosion, and improve bank stability and water quality by reducing sediment and turbidity in waterways.

Projects – small-scale gully repairs through to large-scale gully and instream engineering works, early interventions, and involving and educating landholders in identifying erosion risks.

Learn more here.

Why is seagrass important?

Seagrass provides habitat for juvenile fish and crustaceans that are the basis of economically valuable commercial, recreational, and indigenous fisheries. Seagrass is also a critical habitat for iconic species that call South East Queensland home such as sea turtles, dugongs, and shorebirds.

Seagrass also plays an important role in protecting shorelines through moderating water movements and energy dispersion. Seagrass meadows store a similar amount of carbon (known as ‘blue carbon’) per unit area as forests.

A target to recover at least 5,000 hectares of seagrass by 2031 has been set to enable these benefits to be provided to the environment and the economy. (1988 baseline: 27,085 ha; 2019 interim extent: 22,695 ha).

Citizen scientists keeping an eye on critical marine habitats

Citizen scientists are taking to the water, sampling seagrass and other benthic habitats in Quandamooka (Moreton Bay) as part of the Science Under Sail program. The information obtained informs the management and protection of Quandamooka’s natural assets including seagrass meadows and other habitats.

The data collected contributes to the Ecosystem Health Monitoring Program (EHMP) and informs marine park zoning reviews and land use planning. The information is also made publicly accessible through the Atlas of Living Australia.

The information helps Healthy Land & Water to advise state and local governments on the best way to manage and protect Quandamooka’s natural assets of seagrass meadows and other critical estuarine and marine habitats.