INORGANIC NITROGEN REMOVAL BY Gracilaria verrucosa AT DIFFERENT DENSITY IN THE SHRIMP POND

Abstract

Bitrogen in shrimp pond ecosystem is present in the form of ammonia, nitrite and nitrate. These nitrogen compounds are the indication of eutrophication as nutrient enrichment in shrimp pond ecosystem is caused by the main component of feed, protein. Removal of ammonia, nitrite and nitrate from shrimp pond ecosystem is crucial as these compound are toxic to the shrimp. The aim of this research is to study the efficiency of using Gracilaria verrucosa, for nitrogen removal. The density of Gracilaria was used as treatments. The Gracilaria were arranged at density of 1kg/m2, 2kg/m3, and 3 kg/m3, and each density was put into 1m x 1m x 1.2m polyethylene enclosures, filled with 1 m3 brackish water. The performance of ammonia, nitrite, and nitrate were monitored during 8 weeks of experiments. Results indicated that the presence of Gracilaria significantly reduced ammonia, nitrite and nitrate in the shrimp pond. There was a highly significant correlation between density of Gracilaria with removal of ammonia (r=-0,83*, p=0.02567 n=12). There were also significant correlation between Gracilaria density with removal of nitrite (r=-0.66*, p=0.0488, n=12) and nitrate removal (r=0.58*, p=0.03184 n=12).