Monitoring begins at Devil’s Corner on the shores of Moulting Lagoon (Tas)
In late November 2025, Bec and Justine, in conjunction with local saltmarsh guru John Aalders, undertook baseline vegetation monitoring for potential saltmarsh and wetland restoration areas at the Devil’s Corner property, on the shores of the Moulting Lagoon Ramsar site, east coast Tasmania. NGT had installed hydrological monitoring sites earlier in June 2025. Together, the hydrological and vegetation monitoring programs will help us describe the existing eco-hydrology of these systems and enable the tracking of changes over time pre and post potential restoration works.
The objectives of the monitoring plan were to:
- Collect baseline (pre-restoration) information on the vegetation, water quality and water regime to characterise the sites before potential future restoration works and better understand the impact of previous hydrological manipulations.
- Determine opportunities for positive changes to water regime to improve the condition of vegetation and conservation values of the property.
Key eco-hydrological questions guiding the monitoring at Devil’s Corner include:
North:
- What is the water level and salinity regime of Top Hole and the drainage area to the north and how do these align with those experienced in adjacent Moulting Lagoon and the inflowing creek?
- What is the relationship between water levels in Top Hole, freshwater inflows and tidal levels in Moulting Lagoon?
- Is the eastern drain entering Top Hole affecting the water level and salinity regime (and therefore saltmarsh community condition and extent) of Top Hole and associated low-lying saltmarsh areas to the north?
- Is the culvert under the access track west of Top Hole impacting equalisation of inflows and outflows from Top Hole to Moulting Lagoon?
South:
- How has the western drain impacted the water regime of Middle Hole and in turn saltmarsh vegetation cover and extent?
- Are access track culverts affecting the water level and salinity regime (and therefore saltmarsh community condition and extent) of Middle Hole and associated low-lying saltmarsh areas?
- Is the culvert under the access track west of Middle Hole impacting equalisation of inflows and outflows from Middle Hole to the lagoon?
- What is the water level and salinity regime of Middle Hole and how do these align with those experienced in adjacent Moulting Lagoon?
- What is the relationship between water levels in Middle Hole and tidal levels in Moulting Lagoon and how has this changed over time?
Paired surface water level (SWEL) and salinity (EC) loggers were installed at four sites including Middle Hole, Top Hole, Top Hole northern wetland and Top Hole tidal channel. This data will provide information on the relationship between wetland water levels and rainfall/runoff and tidal inflows.
Two 350-400 m transects were established at Middle Hole and Top Hole northern wetland. These sites were selected as those most likely to show a change in eco-hydrology in response to restoration activities. The Top Hole transect extended to the western side of the access track to see if the improved hydraulic connection beneath the track (and earlier removal of grazing pressure) results in improvement in saltmarsh condition over time. Each transect had 11 x 1m2 plots assessed along it spaced relatively evenly and/or where a change in vegetation community was observed. Species and percent cover were recorded in each plot.
Hydrological and vegetation monitoring locations. Green points = water monitoring locations; blue lines = vegetation transects.
Water Observations
The drain exiting Middle Hole was dry in June and near full on our recent visit in November 2025. The water level in Middle Hole was approximately 0.24 m higher in November than in June 2025.
The channel exiting Top Hole on the western side of the track was flowing out (to Moulting Lagoon) fast during June 2025 and flowing in (to Top Hole) fast during November 2025. The channel water level was so high on the 27th of November that water over-topped the channel and was seeping into adjacent low-lying areas west of the track.
Significant rainfall events were recorded for Apslawn in June (9-11 = 40 mm), July (26-27 = 50 mm), October 23=40 mm) and November (8=30 mm). The largest July event appears to have influenced site salinity the most (coincides with a drop in salinity, followed by a period of stability and resumed increasing trend to November). Salinity trends were consistent between monitoring locations. Salinity has typically fluctuated from 10-60 µS/cm at northern sites. Elevated lower-end salinity at Top Hole and elevated top-end salinity at northern wetland indicate concentration of salt over time. It is obvious that these wetlands maintain strong links to salinity levels in Moutling Lagoon but are also responsive to local rainfall events.
Vegetation Observations
Wetlands and saltmarsh typically grade from peripheral grassland in outer areas into saltmarsh and rushland communities in central areas. Species common in the outer edges of Middle Hole include Poa, Sarcocornia, Plantago and Gahnia. The central, waterlogged areas of the inner Hole are dominated by freshwater/brackish marsh species including Apodasmia, Baumea, Mimulus, Samolus and Selliera. Juncus kraussii was spread throughout.
Wilsonia was only recorded on the edge of Middle Hole and was observed in a distinct patch of gravel on the edge of the northern wetland at Top Hole (see image).
Sarcocornia and bare ground dominated Transect 2. Disphyma and Juncus were only recorded on the western side of the track at Top Hole whereas grasses, Poa and Plantago dominated the eastern edge. Top Hole includes salt pans which will be interesting to observe over time if hydrology is restored.
Whilst the transect at Top Hole northern wetland traverses the middle of the wetland, the area to the north of this will also be important to observe over time as it includes freshwater marsh species (similar to those in Middle Hole) and exhibits an area of interplay between freshwater catchment inflows and tidal connections. If the drain is backfilled to the south, change may become apparent in this northern area as well, and it may extend further south when freshwater inflows are allowed to spread out and mix with southern drained saline areas under a restored scenario (see image).
What are the Next Steps?
Baseline data is currently being analysed and built upon to inform restoration objectives and activities. A restoration plan will be developed for the property by March 2026 and with landowner support, will be implemented by June 2026.
This project is funded by the Australian Government’s Natural Heritage Trust and delivered by NRM South, a member of the Commonwealth Regional Delivery Partners panel.
