Eutrophication trend of southeast Caspian Sea water (Mazandaran-Goharbaran) based on environmental and biotic parameters using single and multiple variables in order to feasibility of marine cage culture

The aim of this project is to study water quality and the trophic status at different months and depths in the southeast Caspian Sea-Goharbaran based on environmental parameters and nutrients during 2013-2014 in order the feasibility of fish cage culture. Results showed that water temperature, transparency, pH, dissolved oxygen, BOD5, COD, total alkalinity and TSS were varied 9.00-29.00C, 0.50-12.00 m, 8.05-8.74, 5.76-12.85, 14-101, 21-195 and 0.00-0.12 mg/l at the different months and depths, respectively. In addition, the values of NH^4+, NH_3, NO^2-, NO^3- and PO^4-3 were 0.007-0.051, 0.001-0.010, 0.002-0.015, 0.043-0.477 and 0.014-0.077 mg/l, respectively. Chl-a concentration was recorded as 0.060-8.02 mg/l. Scaled and unscaled trophic indices were equal to 3.42-5.52 and 2.61-5.85, respectively. The proper temperature for cultivation of salmonids species in this area began from October to March. The range of the standard of pH and dissolved oxygen level for fish farming cage were 7.80-8.50 and >5 mg /l that in current study results of pH and dissolved oxygen which were consistent in the current study. Various forms of nitrogen (ammonium, nitrite and nitrate ) at the different layers were acceptable and less than the threshold limit of Australia and New Zealand. The results of the nutrients concentrations compared with data from the reference years (1996-1996 ) in the Caspian Sea (Goharbaran region) showed that this ecosystem passed from oligotrophic status and shifted to mezotrophic and eutrophic condition. As a conclusion, although nutrients concentrations were acceptable in terms of fish farming cages in this region, some parameters such as chemical oxygen demand and transparency are not suitable for aquaculture industry. Meanwhile, based on various trophic levels, this ecosystem (Gohrabaran region) has a mezotrophic status with a high risk of eutrophication

Study on physic-chemical parameters of waters for fish cage culture site selection in the southern of Caspian Sea

Marine aquacultures growth require good quality water is leading to high efficiency and low risk to human health. In other words, the water quality is a critical factor to success and failure of the aquaculture industry. The aim of this project is to study water quality and the trophic status at the different depths and layers in the southern Caspian Sea based on environmental parameters and nutrients during three periods (2008, 2009 and 2010-2011) in order the feasibility of fish cage. Results showed that water temperature, transparency, pH, dissolved oxygen were varied 5.50-32.60 ̊C, 3.50- 10.00 m, 7.15-8.80 and 3.18-12.00 mg/l at the different depths and layers, respectively. In addition, The values of NH4^+, NH3, NO^2-, NO3^- and PO4^-3 were 0.001-0.140 mg/l, 0.01-22.63 µg/l, 0.1-21.2 µg/l, 0.001-0.423 mg/l and 0.008-0.071 mg/l, respectively. Inorganic nitrogen (DIN/N), inorganic phosphorous (DIP/P) and total phosphorous (TP) were registerd 0.68-14.75, 0.07-0.68 and 0.01-2.67 µM, respectively. Thermal startification are more important for fish-breeding. Thermal stratification was occurred from depths greater than 20 m in late spring to early fall in the Caspian Sea. Optimum transparency for fish farming cage was considered less than 5 meter which in this study were recorded from 20 to 50 meter depths. The range of the standard of pH and dissolved oxygen for fish farming cage were 7.80-8.50 and >5 mg /l that in current study results of pH and dissolved oxygen were consistent.Various forms of nitrogen (ammonium, nitrite and nitrate ) at the different layers were acceptable and less than the threshold limit of Australia and New Zealand. But, phosphate value was more than threshold limit of Australia and New Zealand at some layers depth during years of 2009 and 2010- 2011. The results of the nutrients compared with data from the reference year (1996-1996 ) in the Caspian Sea was shown that this ecosystem passed oligotrophic status and shifted to mezotrophic and eutrophic condition. In addition, the values of NH4/N, NO3/N and DIP/P compared with eutrophic condition of reference year (2005) showed that Caspian ecosystem was not passed euotrophic condition and it still under mezotrophic status. As a conclusion, it seems that offshore of the Caspian Sea (depths between 20 to 50 meter) were suitable for different species of fish for cage culture. But, since 2000 decayds the Caspian Sea has experienced four times algal bloom (toxic and harmful species) and in recent years a number of other species also has reached to bloom potential and also mezotrophic condition of this ecosystem, it is appropriate that the establishment of fish farming cages carried out as a pilot to more precautionary approach which not lead to environmental disaster