Publication Date:
2021-05-19
Description:
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, NO2-, 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.
Description:
Iranian Fisheries Science Research Institute
Description:
Published
Keywords:
Physico-chemical parameters
;
Water
;
Fish cage culture
Repository Name:
AquaDocs
Type:
Report
,
Refereed
Format:
54pp.
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