Ewens Ponds, located in the South East of South Australia, are exceptionally clear-water wetlands dominated by macrophytes, which provide critical habitat for protected aquatic species including the critically endangered Glenelg Spiny Crayfish (Euastacus bispinosus).
Regional changes in land use from native vegetation to pasture, and alteration of the hydrology due to increased water extraction, decreased the quantity and quality of groundwater flowing into Ewens Ponds. Episodic occurrence of cyanobacterial blooms and epiphytic algal growth are initial warning signals of deteriorating water quality. Similar freshwater ecosystems have responded in a drastic way to increasing nutrients shifting from a clear-water macrophyte-dominated state to a phytoplankton-dominated state, with concomitant reduction in ecosystem health.
There is increasing concern that pelagic and epiphytic phytoplankton might outcompete macrophytes in Ewens Ponds causing habitat degradation and loss of endangered species. The uniqueness of the ponds and their regional and global importance are motivators for their protection and the maintenance of suitable water quality and flow.
The project aims to identify the most significant threats to high value wetlands in the South East.
The key findings related to the risk of regime shift in Ewens Ponds were:
The key findings related to the alkalinity were:
This project provided scientific knowledge to anticipate drastic change in ecosystem dynamic avoiding consequent loss of habitat function for threatened species.
Project outcomes allowed identifying the stressors that interact controlling water clarity and alkalinity in South East wetlands. This enabled support of water quality and conservation management decisions. Additionally, approach and tools adopted can easily be picked up by government and managers to reduce and manage risks.