Water quality dynamics in brackishwater shrimp ponds with artificial aeration and circulation

Abstract

Water aeration and circulation using paddlewheel aerator and motor-driven propeller blades, respectively, were maintained under four different diurnal regimes to test their effects on water quality and production of Penaeus monodon. Shrimp with an average weight of 0.03 gm were stocked at density of 33 individuals/square meter in four 0.05-ha earthen ponds. The four treatments were: (1) continuous aeration, (2) nighttime aeration, (3)nighttime aeration and daytime circulation, and (4) no aeration or circulation. Ammonia nitrogen (NH3-N), dissolved oxygen, temperature and shrimp growth were monitored during a culture period of 10 weeks. Ammonia nitrogen concentration did not differ significantly under the various aeration and circulation treatments. Dissolved oxygen and temperature stratification was least evident in treatments 1 and 3. Nighttime dissolved oxygen levels were significantly lower in treatments 1 and 4. The average size of shrimp at harvest was significantly higher in treatments 1 and 3. These findings taken together indicated that there was no clear benefit from continuous aeration. Rather, a combination of nighttime aeration, when needed, and daytime circulation could result in the greatest water quality benefits with the least energy consumption.