AQUATIC AND BENTHIC BACTERIA RESPONSES TO FEED AND FERTILIZER APPLICATION IN TRIALS WITH THE FRESH-WATER PRAWN, MACROBRACHIUM-ROSENBERGII (DE MAN)

The effects of formulated feed and organic fertiliser on aquatic and b enthic bacterial populations and on production of the freshwater prawn Macrobrachium rosenbergii (de Man) were assessed. Prawns were culture d in pond enclosures to which pelleted feed and/or chicken manure were added. Prawn survival was high but growth poor. Total bacterial abund ance, mean cell volume and biomass, determined respectively by epifluo rescence microscopy, image analysis and conversion calculation, illust rated the effect of treatment on the water and sediment bacterial popu lations. Differences in bacterial abundance and mean cell size were ev ident between treatments. The discussion considers the importance of b acterial productivity and food web dynamics.