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Saliza Mohd Nazri Doctor of Biotechnology Analysis of Jacobs SKMs benchmark study on effluent emissions from shrimp aquaculture and sugarcane farms 1

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Introduction Jacobs SKM was contracted by QCA to give independent advice on environmental and technical issues in the investigation on the regulatory reform of aquaculture in Queensland [1]. Table 1. Summary of effluent emissions by Jacobs SKM [1]. 2

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Comparison Table 1. Summary of effluent emissions by Jacobs SKM [1]. Table 2. The effluent discharge data from prawn aquaculture farms based on CRC Report 2002 [2] (note: units have been converted to the same unit used by Jacobs SKM for ease of comparison). 3

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Prawn farm effluent data from Jacobs SKM benchmark study 4

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Investigation of the value stated in the benchmark study First row of prawn farm discharges The original study was conducted by Trott and Alongi [4] but was cited in Burfords [5] review. The prawn farm pollutant loads did not lead to eutrophication due to physical and biological processes associated. Examples of the associated processes : 1)the fast settlements of the nutrients within the creeks and forests, 2)the efficient flushing and removal process of sediments during high currents and fluxes, 3)the primary production undergo grazing by the zooplankton, 4)the consumption of zooplankton by juvenile fish 5) the effluent discharges were in an intermittent pattern that permitted the fallowing to take place at the estuary [4]. 5

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Investigation of the highest N value stated in the benchmark study (prawn farm discharges) Derived from a study done by Jackson [6] which investigated the effluent loads from three intensive shrimp farms in Australia. In the study, it was reported that due to the unusual condition of Farm A, only the discharge values obtained from Farm B and Farm C should be used as indicator of the pollutant loads released from intensive shrimp farms [6]. This is because Farm A used double amount of water (1.36 X 10 6 L ha -1 day -1 ) as the management changed its main shrimp production species from P.monodon to M.japonicus in the early of the study and faced difficulties from the switch. 6

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Jackson [6] proposed in the conclusion of his research, intensive shrimp farms would typically produce 1 kg ha -1 day -1 (365 kg ha -1 yr -1 )of net loads of total nitrogen. In conclusion, if a correction was to be made in the benchmark study, the 657 kg ha -1 yr -1 value of nitrogen effluent stated would be replaced with 365 kg ha -1 yr -1. 7

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Sugarcane farm effluent data from Jacobs SKM benchmark study 8

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Jacobs SKM referenced a report done by Dr McPhee [7] in the first row of the benchmark study of the sugarcane farm effluent data. However, a further investigation into this report by McPhee revealed that there was also data on the nitrogen emission from sugarcane farms of 300 kg/ha/yr reported in 1990s (on page 7 of the report). Hence, there is a big area of improvement needed on the conclusiveness of the data extracted by Jacobs SKM. If this had been reported in the benchmark study, the N emission level would be double than the present data and this would lead to a different conclusion regarding the relative contributions to effluent loads in GBR. 9

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