The effects of paddlewheel aeration and stocking density on water quality and production of Macrobrachium rosenbergii (de Man) under monoculture system
The effects of aeration and stocking density on water quality and production of Macrobrachium rosenbergii were examined in six 0.54 ha ponds in Nakhon Pathom province, Thailand, during a grow-out period of eight months. The experiment comprised three treatments; T 1) 20 prawn/m2 stocking density with aeration, (T1), 2) 20 prawn/m2 stocking density without aeration (T2), 3) 10 prawns/m2 stocking density without aeration (T3). The ponds of treatment 1 were subjected to the aeration by means of ele ctric-powered paddlewheel aerators, after 3-months of stocking. Prawns were fed a formulated pellet feed once a day approximately at the rate of 5% of body weight. Prawns were partially harvested 3 times before total harvest. In all the ponds, the survival rates were very low (T1=18%, T2=15%, T3=18%). Because of the heavy mortality occurred during the grow-out period, much desired data could not be collected. However, when the collected data were statistically analyzed no significant differe nces were observed between the treatments with and without aeration or with varying stocking density on water quality and survival rate. Production was low in low density (551 kg/ha) compared to the high density (876–894 kg/ha). Mortality occurred during the experimental period was mainly due to sudden falls of temperature, high rates of liming, and DO depletion. Oxygen depletion was resulted from phytoplankton blooms and their sudden die-offs due to heavy rainfalls. Paddlewheel aerator used, proved to be insufficient to raise the DO (water depth 1 meter) level at such time.
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| Format: | Project biblioteca |
| Language: | English |
| Published: |
1986
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| Online Access: | https://openknowledge.fao.org/handle/20.500.14283/AC224E http://www.fao.org/3/a-ac224e.htm |
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