A survey on environmental effects of shrimp pond culture effluents in Gwatar area (Sistan & Blouchestan)

Present project was conducted in shrimp farm located in east of Chabahar in Sistan and Balouchestan province.Twentieth sampling stations at three locations (i.e. 2 stations in supply channel,13 stations in drainage channel and 5 stations in Gwatar Gulf) were selected to determine physical and chemical factors such as; temperature, salinity, dissolved oxygen, pH, nitrate, nitrite, ammonia, phosphate and biological parameters for example Chlorophyll a, phytoplankton and zooplankton. Sampling was conducted once a month from March 2003 until January 2004. The results revealed different bioenvironmental area in the three locations (i.e. supply channel, drainage channel and Gwatar Gulf) over the study period. Concentration of salinity ,pH , nitatr ,nitrite ,ammonia and chlorophyll a in drainage channel were more than supply channel and Gawtar Gulf. While concentation dissolved oxygen and phosphate were in drainage channel less than Gawtar Gulf.Also, sediment with small grain size (clay and silt) caused uptake phosphate and amount phosphate decreased in drainage channel. Considering with lack of environment standards in Iran shrimp effluent, data compared with others countries standard. Results showed that with considerable farm area, value of temperature, salinity, dissolved oxygen and pH were in permit range in Gwatar Gulf while concentation nitrate, phosphate and chlorophyll a were sometimes more than permit range that could cause plankton bloom. Also, Gwatar Gulf were influence monsoon. Nitate, phosphate, chlorophyll a and phytoplankton increased in gwatar Gulf.Regards with that postmonsoon was simultaneus with shrimp harvest.Therefore, increase some parameters could be caused from shrimp effluent or postmonsoon. Thirty four phytoplankton genus were identified including diatoma, dinoflagellate, cyanophyta and chlorophyta. In each area maxiumum percentage of phytoplankton were belonged to diatoma (63%) in supply channel, cyanophyta (51.7%) in drainage channel and dinoflagellate (94.5%) in Gwatar Gulf.Amount and range chemical and physical factors and plankton composition were different in drainage channel, supply channel and Gwatar Gulf. Cyanophyta could grow more in drainage channel.Percentage of aboundance and diversity of phytoplankton changed in 2002 inrelation to years ago( before shrimp culture, 2000 year and 2001 year) specially in Gwatar Gulf. Mainly percentage of zooplankton were copepoda and thintinida respectively.Diversity zooplankton decreased ratio to years ago. In drainage channel, abundance total of phytoplankton and zooplankton were more than Gwatar Gulf and supply channel