Impact of fish cages on the Nile water quality at Damietta Branch

Damietta region has been drastically affected by increasing levels of pollution from point and non-point sources; domestic, industrial, agriculture as well as the extensive fish cages in the region. The aim of this study was to monitor the Nile water quality at Damietta region through measuring of physico-chemical parameters and some heavy metals; to investigate the impact of decision maker on fish cages removal from the study area. Water samples were collected along axial transect of Damietta branch twice; the first monitoring campaign was conducted at the end of autumn 2006 just after the removal of fish cages from the Nile while the second campaign was carried out at the end of winter 2007. A water quality index (WQI) was used as a simple pollution indicator to assess the effect of fish farming. The results revealed that, DO concentrations ranged from 4.4 to 9.2 mg/l; BOD values are in the range of 1.1 - 4.6 mg/l, whereas COD ranges from 31.6 to 146 mg/l. Ammonia, nitrite and nitrate ranged from 0.246 to 0.480, 0.056 to 0.115 and 0.075 to 0.155 mg/l, respectively. Total phosphorus ranged from 0.014 to 0.199 mg/l. The Nile water quality at the study area has been improved after the removal of fish cages. Water quality index used supports this finding; water quality improved from _medium_ during the first filed inspection into _good_ quality during the second filed sampling at the end of winter 2007. Thus, fish cages removal from Damietta branch improved water quality.