Open Cut » Environment
Salinization of freshwater systems is being increasingly recognised as a global issue. Regulating diffuse and point source saline inputs to freshwater systems is difficult owing to the complex interactions that influence both the direct and indirect effects of salinity on individual species and in ecosystems. There is increasing evidence that ion composition can play an important role in defining species distributions and in toxicity.
The aim of the project was to develop a locally relevant salinity toxicity data set for aquatic organisms in rivers of the Southern and Western Coalfields of New South Wales.
The specific objectives of the work were:
· To undertake acute toxicity tests to determine the tolerances of selected aquatic macroinvertebrates from representative catchments, to saline solutions representative of ionic compositions of mine waters in the Southern and Western coalfields;
· To undertake acute and chronic tests on representative mine water's ionic compositions using a standard suit of laboratory reared taxa (representative of the regions) to compute levels of ecosystem protection afforded by different salinities.
· Compare results from literature and recent ACARP funded work to build a comprehensive library of salinity toxicity results using mixed salt solutions that can be presented to regulators. Acute toxicity tests were conducted using artificial mine water solutions and mayfly larvae collected from the Georges River in the Southern Coalfields and a tributary of the Wollangambe River in the Western Coalfields. Additional acute and chronic tests were conducted using artificial mine water and commercially available, laboratory raised organisms representative of those in the catchments. Artificial mine water compositions were based on a survey of mine water from two mine sites located downstream of the collection sites.
The 95% ecosystem protection value calculated from species sensitivity distribution for the Georges River was 800 μS/cm and 901 μS/cm in the Wollangambe River. These locally derived salinity trigger values are higher than the range recommended for upland streams in NSW (ANZECC/ARMCANNS, 2000). These results should be examined in conjunction with previous ecotoxicity experiments and the biomonitoring data to examine the trends from a multidisciplinary perspective.