Research note: riparian threats in the Kimberley, a focus on the Fitzroy river catchment

Fieldwork along the Fitzroy river

The contribution of riparian or riverine habitats to biodiversity conservation and the economy is disproportionate to the small area they occupy in the landscape. However, these unique habitats are facing numerous threats, including invasion by weeds.

A new 3 year project funded by the Northern NESP Hub aims to generate insight on direct and indirect impacts of one of the most significant problem weeds in North West Australia, stinking passionflower (Passiflora foetida), broadly on riparian communities and more specifically on the endemic Australian Freshwater Crocodiles (Crocodylus johnstoni).  The project will focus on the largest river catchment of the Kimberley region – the Fitzroy and will ultimately generate critical information on how to more effectively manage biodiversity threats.

A recent scouting trip to the catchment took the Ecosystem Change Ecology team from the headwaters of the Fitzroy through Mornington station to the lower reaches around Udialla, identifying study sites for long-term monitoring programs.

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Rain during the wet season causes the Fitzroy River to have the highest water flow by volume for any river system in Australia and transforms the landscape significantly while causing heavy floods. Photo: © Ruchira Somaweera

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The man-made irrigation canal, Snake Creek, is inhabited by a large population of freshwater crocodiles, as well as saltwater crocodiles, freshwater sawfish and bull sharks, emphasising the importance of alternative permanent water habitats in arid Kimberley landscapes. Photo: © Ruchira Somaweera.

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Launching a boat at an isolated pool where crocodile nesting takes place in the vicinity of Liveringa. The Nyikina-Mangala Rangers provided on-ground support for this phase of the trip. Photo: © Ruchira Somaweera.

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The team crossing a shallow section of the Fitzroy River near Geikie Gorge NP. Photo: © Ruchira Somaweera.

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Stinking passionflower (Passiflora foetida) covering a once open sand bank at Geikie Gorge NP. The human scale provides context for the extent of weed coverage. Photo: © Ruchira Somaweera.

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Trampling by cattle is significantly transforming riparian environments in the Fitzroy catchment, impacting on terrestrial and aquatic vegetation as well as water quality. Photo: © Ruchira Somaweera.