Oral Presentation Australian Society for Limnology Congress 2013

Assessing the effect of salinity on stream macroinvertebrate communities: the case of the Hunter River Catchment, New South Wales? (#108)

Ben J. Kefford 1 , Jan Miller 2 , Martin Krogh 2 , Ralf B. Schäfer 3
  1. University of Technology Sydney (UTS), Broadway, NSW, Australia
  2. Office of Environment and Heritage, Department of Premier and Cabinet, Sydney, New South Wales, Australia
  3. Institute for Environmental Sciencesy, University Koblenz-Landau, Landau, Germany

Licensed discharges of saline effluent from coal mines and power stations occur in the Hunter River catchment. Since 1994 a salinity trading scheme has largely been successful at preventing salinity levels rising above target levels of 600 and 900 µS/cm in the upper and the mid-lower Hunter River, respectively. Determining whether these levels are protective of ecosystem health in the Hunter Catchment is complicated by natural sources of salinity, salinity often occurring in pulses, variation in ionic proportions of salinity and salinity concentrations being confounded with other environmental fluctuations. Here we examined changes in stream macroinvertebrate traits and large-scale turn-over of families with increasing salinity in the Hunter River and adjoining catchments (Karuah River, Lake Macquarie, Tuggerah Lakes and Manning River). Increasing salinity was found to be associated with a reduction in the abundance of salinity sensitive families, as indicated by laboratory tests. There was also a greater reduction in the abundance of families which were both salinity sensitive and have traits making their populations likely to recover slowly from pulse disturbances. These results suggest that salinity, especially pulses of salinity, are potentially altering macroinvertebrate communities, although evidence that other environmental factors may also (partly) play a role will be presented. We found that as EC increased, there was significant turnover in macroinvertebrate families including below salinity levels of 600 and 900 µS/cm. In conclusion, salinity changes in the Hunter and adjoining catchments are potentially (in conjunction with other variables) affecting macroinvertebrate community structure.