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.