Application of extracellular enzyme techniques to studying the role of bacteria in the ecology of prawn ponds and diseases of P. monodon and P. japonicus
Western Sydney University Macarthur
In discussions with farmers in Queensland and NSW, it is clear that there are few indicators of prawn health, pond productivity or pond processes. Farmers and researchers are often at a loss to account for considerable differences in productivity, survival and growth rates between ponds. Nor has it been possible to forecast die-offs or deterioration in the health of prawns from conventional measurements of water quality or microbiology. Hence, as the industry matures and seeks to attain more consistent productivity, there is an urgent need for more sophisticated methods of assessing the status of ponds and the value of various pond management practices. This project aims to increase farm productivity by studying the bacteriology of prawn ponds. Bacteria are the most abundant organisms in prawn ponds, being ubiquitous in all types of sediment, water and organisms at farms. Their processes determine: the fate of most organic matter in ponds, water quality, sediment condition and the health of prawns. For example, the toxins produced by pathogenic luminous bacteria, Vibrio harveyi, recently have been shown to be extracellular enzymes which digest proteins. Further, the hypothesis we have proposed that black marks, tail rot and necrosis of prawn antennae are due to extracellular enzymes, chitinases, needs to be investigated. Thus there is a need for a new and more powerful approach to this issue, in that the PROCESSES carried out by the bacteria need to be studied, rather than the numbers and types of bacteria. Hence the proposed farm-based study is needed to provide the industry with sensitive, robust, inexpensive and rapid bio-indicators which can be used to assess and forecast pond productivity.
1. To apply recently developed technologies for bacterial enzyme analysis to the study of microbial processes in prawn farms.
2. To investigate the bacteriology of prawn ponds throughout the entire growouts for ponds at five Australian farms.
3. To investigate relationships between bacterial enzymes and pond productivity, with emphasis on prawn health, growth rates, feeding strategies and prawn survival.
4. To determine which are the key bacterial extracellular enzymes to study when making a rapid assessment of the status of a pond for HACCP (Hazard Analysis for Critical Control Points).
5. To investigate the associations between the various pond management practices on bacterial enzymes and pond conditions.
6. To compare the bacterial enzymes of ponds used to culture P. monodon and P. japonicus.
7. To effectively communicate the results of the study to the prawn farming industry and fisheries departments through a manual for farmers on the impacts of management practices on pond bacteriology and productivity.
Principal Investigator: Paul T. Smith