The Aquafin CRC Salmon Project is being undertaken by CSIRO Marine and Atmospheric Research (CMAR) and Tasmanian Aquaculture and Fisheries Institute (TAFI). Prior to the three microheterotroph grazing experiments, a CTD cast was performed at site PE3 to determine the depth of the fluorescence maximum. Water for the three grazing experiments was collected simultaneously from a depth of 7m. For all three experiments, the sample water was filtered through a 200µm mesh as usual. For the second experiment, 10 mesozooplankton were added to the sample water in each incubated bottle. In the third experiment 30 additional mesozooplankton were added to the sample water in each incubated bottle. The additional mesozooplankton were removed from the incubated bottles at the close of the experiment, before filtration. Samples were incubated for 24 hours with subsamples collected at times T0 and T24 for phytoplankton and microheterotroph counts, nutrient analysis and pigment concentration and composition. Grazing and growth rates were calculated.