The assessment quality of effluent from shrimp aquaculture site in Gwater

Abstract

Present study was conducted in shrimp farm located in east of Chabahar in Sistan and Balouchestan province from August 2001 until May 2003. Fourteen stations at three locations (i.e. supply channel, drainage channel and Gwatr Gulf) were selected to determine physical and chemical factors such as; temperature, salinity, dissolved oxygen, pH, nitrate, nitrite, ammonia, phosphate, silicate, total suspended solid and turbidity. Sampling was conducted twice a month during the shrimp culturing period and monthly at other times. Water samples were collected every two weeks to determine Chemical and Physical factors, Chlorophyll a, Phytoplankton and Zooplankton. Sediment samples were collected seasonally to examine Macrobenthos, Grain size and Total Organic Matter. The results revealed different bioenvironmental area in the three locations (i.e. supply channel, drainage channel and Gwatr gulf) over the study period. One-way analyze of variance of chemical and physical factors indicated significant difference between different times as well as different stations (p<0.05). The negative relationship was observed between the culturing production area and the amount of average dissolved oxygen, pH and total suspend solid. An increase in the culturing production area in 2002 as compared to that of 2001 causes a decrease in the amount of these factors. However, it dose indicates positive relationship with nitrate, nitrite, ammonia, transparency and chlorophyll. Forty nine phytoplankton genus were identified, which mainly belong to diatoma, dinoflagellate and green blue algae. Diatom was dominated among these groups. Diatom and green-blue algae and diatom comprised %79, %69 and %64 of phytoplankton flora respectively in supply channel, Gwater Gulf and drainage channel. Copepod and thintinnida were the major groups of zooplankton. High abundance of bivalve, Polychaetes and amphipoda were found in supply channel, Gwatr Gulf and drainage channel respectively. Analysis of grain size showed the existence of sandy sediment in Gulf of Gwatr and sandy-loom in supply channel. Drainage channel sediment found to be sandy-loom, sandy-silty-loom and sand loom. Among three locations, the highest TOM was found in drainage channel. In last location, production area in 2002 increased as compared to that of 2001, which showed negative relationship with salinity, nitrate, nitrit, ammonia and chlorophyll a. Drainage of the Gwatr s shrimp farm did not cause any thermal contamination in the location. Shrimp aquaculture activities caused an increase in the average of salinity, range of pH in the Gwatr Gulf.