Field methods
Water temperature, pH, salinity and dissolved oxygen were measured in situ with a TPS meter (TPS MC81Brisbane,Australia) at each site in all lakes. The pH meter was checked at the beginning of each day's samplingagainst known pH buffer standards (pH 4.0 and 6.88). Salinity probe was checked against known standard
of 2 ppt. These parameters were measured at a fix depth of 0.5 m. Water transparency was determined with
a Secchi disc.Samples taken for laboratory analysis were collected using an integrated water sampler, which collected watersamples from surface to a depth of 1 m. Samples were transferred into 1 litre polyethylene bottles that had been
cleaned with 10% HC1 and rinsed with de-ionised water.All samples were placed on ice in a cooler for transport
to the laboratory and analysed within 24 hrs of collection.