The Use of Mechanical Aeration and Its Effects on Water Mass

Due to the increasing use of artificial aerators in fish ponds, and to the lack of studies on this subject, this work studied some of the aspects associated with their use. The influence of a diffuser type aerator (AR 120) on the biotic and abiotic variables was evaluated in a fish pond. Three points of the pond were marked for the taking of samples: 5, 10 and 23 m from the aerator. Samples were taken every day for 15 consecutive days: 5 days before the use of the aerator, 5 days with the aerator functioning and 5 days with it not functioning. The limnological variables studied did not show significant differences (P > 0.05) when the three sampling points were compared, but regarding the use of the aerator, variables such as water temperature, transparency, pH, dissolved oxygen, bicarbonate, free CO 2 , total phosphorus, orthophosphate, ammonia nitrate and nitrite concentrations showed significant differences (P < 0.05) when the water was mechanically agitated. There were no significant differences (P > 0.05) with the use of the aerator regarding conductivity, alkalinity, total CO 2 and chlorophyll a values. The phytoplanktonic community suffered as a direct influence of the aerator (P < 0.05). The community was dominated by Chlorophyta, representing more than 70% of the total organisms present, followed by Cyanophyta and Chrysophyta which tended to increase in number after the use of the aerator. This probably occurred because these groups adapt quickly to changes in the environment.