The Sandringham Wetland Complex Project is a sub-component of the overarching ‘High priority coastal and island restoration for the protection of significant ecological communities and species project’ informally known as the Coastal Priorities Project. The project is supported by Reef Catchments through funding from the Australian Government’s Reef Trust Program.
The Sandringham Wetland Complex provides many important functions to Mackay coast due to its unique soils and water-holding capacity. These functions are referred to as ‘ecosystem services’. Wetlands are the boundary between two different ecosystems, dry and wet, which means they have a unique role in the nutrient exchange and water supply to the surrounding lands, as well as providing habitat, food and shelter to many different plants and animals.
Wetland habitats are an important part of many grazing properties in Queensland. Most wetlands in Queensland are on privately owned or managed freehold or leasehold lands, many of which are grazing enterprises. Improvements and adoption of best management practices on these important ecosystems can enhance ecosystem services and improve grazing systems.
The Sandringham Wetland Complex is valued by graziers for providing water and feed for stock and security during the dry season and/or droughts. The impacts of grazing on wetlands can include reduced water quality from additional nutrient inputs and increased soil compaction, reduced native vegetation and subsequently reduced habitat for native species, and reduced capacity of the wetland to provide filtration and water quality ecosystem services.
This project has involved assisting landholders in the wetlands area to better manage their land and their own practices to optimise the balance between production and ecosystem protection. Some examples of this include the construction of fences and off-stream watering points (OSWPs), leading to better grazing control which in turn improves production values and improves the condition of the ecosystem and ultimately provides water quality outcomes.
Fencing and off-stream watering points
Project efforts were directed to the management and restoration of wetlands for their intrinsic values and broader contributions to healthy ecosystems in the Great Barrier Reef. This was done in the way of providing monetary and technical assistance to landholders interested in improving their management practices and consequently their wetland habitats.
Funding for infrastructure to assist with this goal in the form of fencing and off-stream watering points occurred to help better manage cattle on properties. This infrastructure offers pathways to better control the length of time, time of year and the number of stock that can access wetlands, salt marshes and other sensitive areas.
Infrastructure delivered
Across the five year project, fencing and off-stream watering points installed in the Sandringham Wetland Complex totaled:
Fencing: 13km
Fencing comprised a combination of permanent single-wire electric and five-wire steel fencing.
Off-stream watering points: 12
Off-stream watering points were a combination of permanent and mobile points.
Total hectares covered by practice change due to fencing and OSWP: 120ha
Overall, this translates to an impressive area that is subject to improved management practices (i.e. changing management to better benefit both the enterprise AND the environment).
Weed Control
Another goal of this project was controlling aquatic weed species to help improve water and habitat quality. If left to colonise and spread, invasive non-native plant species can have a dramatic effect on the natural environment such as:
- Forming thick mats to prevent light penetration on submerged aquatic native plants
- Blocking the flow of water through creeks and reducing fish activity
- Reducing water quality by preventing light penetration, trapping silt and reducing oxygen
- Out-competing and smothering native vegetation
- Increase flooding potential by reducing the flow capacity of drainage networds
For the Sandringham Wetland Complex, the focus was on water hyacinth (Eichhornia crassipes), a rapidly spreading invasive species which had been established in dams within the area. The species is a major pest in rives and dams and is known to double in size every week under ideal conditions, meaning without intervention, it could completely take over a dam. Below shows the irrigation dam we targeted with extensive coverage of water hyacinth.
Mechanical removal of the plant was employed to minimise the effects of herbicides on water quality. Using a long-reach excavator, the water hyacinth was carefully removed to restore the wetland back to a higher functioning.
The program was incredibly successful at removing the weed, however, long-term monitoring and management of species like water hyacinth are needed to ensure all plants were removed, and none are transported back into the area through floods, birds etc. See the image below for the final result!
Fish refuge and connectivity
What happens when it all dries out?
Wetlands are exceptional for providing many services that other ecosystems cannot provide. Unfortunately, these services can be interrupted by things like weed colonisation, our changing climate and development.
One particular focus for this project was safeguarding our native fish species (and many other species that rely on water sources such as birds) in drier times. Many of our native fish species are diadromous, meaning they need both salt and fresh water to survive and reproduce. There are, however, a few key threats that can get in the way, such as:
- Weed infestations blocking waterways and passage between fresh and salt water
- Changes to water regimes
- Changing climate causing drier/wetter periods
To help safeguard the fish that utilise the largest wetland pools in the Sandringham Wetland Complex, Reef Catchments undertook significant work to help create an environment that will support them even in dry times, and reconnect it with the surrounding waterways.
The first goal: Removing sediment buildup in the wetland and re-establishing deep channels and large refuge pools that won't dry out even in dry years.
Through dry periods of the year, these bunded wetlands can dry up significantly. This reduces available resources for our fish species, but can also expose them to a greater rate of predation given the pools they are left in can be quite shallow.
Because of this, Reef Catchments worked with landholders to establish deeper channels through the wetland, along with deep pools (4 metres at deepest) containing root balls that can act as a refuge for fish in drier times. The root balls also provide hiding spots for the fish, but also benefit native birds, and aquatic invertebrates
The extent of work should mean that our native fish species can survive long into the future within the wetlands.
The second goal: re-establishing connectivity between the bunded wetland and Sandy Creek to allow for fish movement back and forth.
The Solution: Rock Ramp Fishway
Fishways come in a variety of forms, but the style used at Sandringham was a rock ramp fishway. These fishways are commonly used for low-height barriers up to about 2m. Rocks are strategically placed immediately below a barrier to create a low slope which simulates a rocky stream bed. Large boulders are placed periodically along the rock ramp which help to create pools of low flow and low turbulence, allowing the fish to move from pool to pool easily, as well as provide an opportunity to rest and recover, before moving to the next pool.
A wave of new life
When our native fish are young, they are only capable of very small bursts of speed, which they typically use to cross areas of high velocity on their migration. Unfortunately, this means that for many areas, such as culverts and road crossings, the water is going too fast for the juvenile fish to cross and complete their migration. For example, juvenile Barramundi (Lates calcarifer) are known to migrate upstream into freshwater to develop and grow, before migrating downstream into salt water where they spawn. Therefore, without the ability to migrate between fresh and salt environments, they cannot reproduce effectively.
In a rock ramp fishway, rocks are strategically placed to influence the flow of the water in a way that makes it possible for a small fish to swim upstream. If you think of it as an underwater staircase, the fish can rest on top of each stair before tackling the next.
A New Design
Restoring native vegetation in key areas
As part of our remediation works, we are establishing areas where native vegetation will be restored.
These areas will act as shady spots for cattle to recuperate, but also to provide shaded areas around the wetland to ensure water temperatures are kept cool for fish and aquatic plants by the canopies of the plants in hot periods.
Native tubestock was sourced from the Mackay Natural Environment Centre and grown from locally sourced seed. 4000 plants with mulch and irrigation systems in place to help their survival rates.
Some areas were also planted using Ekidna Tree Guards. These guards are designed to keep cattle away from the tubestock so they aren't eaten, tramped or bumped. The guards are re-usable once plants get to a size that cattle wont disturb.