Thursday, 13 July 2017

Salt Pans of Wunjunga

Bowen famously has a salt mine at the entrance to the town. Tourist information used to impel people not to be put off by the ugliness of the salt flats and to continue through to the town. Yet in their own way hypersaline environments are beautiful and interesting. The only place I have found a publicly accessible salt pan which dries to a salt crust is at Wunjunga, which is just south of the Burdekin and on the Bruce Highway.  Driving into Wunjunga during the wet is like driving through a lake.

In the wet season, the salt pan is a shallow lake
Mosquito larvae are present in numbers so don't go there at night if you value your blood

A freshwater fish (spangled perch) swimming on its side in shallow water in an attempt to find freshwater
During the wet season when rains are heavy, the salt flats on the inland side of the salt pan complex drain slowly and become temporary freshwater wetlands.

Bird life is intense, so many birds and so many species
Some birds are timid but others will tolerate a careful approach
Closer to the coast tidal influence dominates and signs of freshwater influence are lost. Just before the beach is a shallow basin that is a saltwater lake during the wet season (shown above), and a bare salt pan with a small hypersaline lake in the dry. Large salt crystals form patterns in this lake.

The shallow lake almost completely dries

The bottom of the lake is encrusted with large cubic salt crystals

Delicate petals of salt spread over the surface
On the bare dry silty surface exposed by the drying lake there are unexpected signs of life. Every solid object is encrusted in barnacles, all dead as the lake fills seasonally and not with tidal cycles. A non-tidal saline lake with barnacles is not a common thing. The only other occurrence that I could find was the Salton Sea, a lake in California that is 70 m below sea level. The beach there is actually composed of barnacle shells. At Wunjunga, meat ants range across the bare flats and probably consume the dead barnacles, leaving empty shells.

Barnacles encrust every surface
A large green tiger beetle was running around in a completely bare expanse. Tiger beetles are predators and I assume they specialise in feeding on insects that land on the salt pans. When I tried to catch the beetle, it ran so erratically that it was almost impossible to catch. Tiger beetles can fly as well as wasps but their running skills are even better.

At the edges of the bare flats, succulent Tecticornia shrubs resemble staghorn coral. Their flowers are almost microscopic yellow specks that poke out between the stem segments. After colouring up, the stems shrivel, releasing segments that contain seed.

Tecticornia going purple

A diversity of succulents is present
Small banks of raised ground lie within salt pan and support an array of grasses and succulents. These areas are important to nesting birds and with their light silty soils are rather delicate places. Tread carefully in these places and look for animal tracks.  For such a harsh environment, there is plenty to find if you take the time.