Aquafin CRC Salmon Project - Process Study 3- Microheterotrophic Grazing Experiment - North West Bay - October 2006

The Aquafin CRC Salmon Project is being undertaken by CSIRO Marine and Atmospheric Research (CMAR) and Tasmanian Aquaculture and Fisheries Institute (TAFI). Process Study 2 was undertaken between 3-5 October 2006 in the North West Bay. Prior to the three microheterotroph grazing experiments, a CTD (Seacat 4550) cast was performed at site NWB2 to determine the depth of the fluorescence maximum. Water for the three grazing experiments was collected simultaneously from a depth of 15m. For the first experiment, the sample water was filtered through a 200µm mesh. For the second experiment, no screening was used for the sample water. In the third experiment approximately 100 ml of water containing microzooplankton, which had been previously screened through a 1mm-mesh, was added to the sample water. 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.