Applying Effective Microorganisms (EM) on the Water Quality Inprovement in the Shrimp Ponds: A Primary Study

摘要

In this study, four ponds were selected for the cultivation of white shrimp. Two ponds were supplemented with effective microorganisms (EM), and two ponds were not added. During the ten-week experiment period, the water temperature, pH, dissolved oxygen, redox potential, BOD, ammonia nitrogen, nitrite concentration and the number and types algae were recorded every one or two weeks. The first eight week data showed that the Pond A and B, with the supplement of EM, had significantly better oxidation-reduction potential than Pond D, which was not supplemented with EM. The data from algae analysis showed that the ponds treated with EM were rich in algal diversity and appeared brown water color earlier than Pond C and D. Unfortunately, a lot of shrimp died in Pond D, due to the sudden heavy rain followed by high temperature. To reduce the loss, the farmers moved the sick shrimp from Pond D to Pond A and B, causing death of shrimp in Pond A and B too. Since it was not possible to confirm whether the shrimp deaths in Pond A and B were caused by sudden climate change or pathogens from the sick shrimp, the experiment stopped in the tenth week.