Background and Objective: In the present study, trophic state of Valasht Lake was investigated monthly at 3 stations, from December 2008 to December 2009. The purpose of this study is investigating the trophic state of the lake and introducing the basic solutions to mai More
Background and Objective: In the present study, trophic state of Valasht Lake was investigated monthly at 3 stations, from December 2008 to December 2009. The purpose of this study is investigating the trophic state of the lake and introducing the basic solutions to maintain this valuable ecological resource. Method: Trophic state index (TSI) was used in this study. Also, the effective parameters on primary production and trophic state determined in this study include: total phosphorus (TP), total nitrogen (TN), a-chlorophyll, Secchi depth (SD), and TN/TP ratio.The results from all mentioned parameters were compared with different trophic levels of fresh water lakes published by U.S Environmental Protection Agency and Organization for Economic Cooperation and Development. According to trophic state index and based on nutrient levels (phosphor and nitrogen), Valasht lake is classified in Mesotrophic to Eutrophic state and based on the other mentioned parameters, it is classified in mesotrophic state. Results: Mean rate of trophic state index reveals the mesotrophic state in this lake. According to the results of Red Field ratio and TSI, nitrogen and turbidity, especially in wet (rainy) seasons, are the main determinative parameters in primary production in Valasht Lake.
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Introduction: In general, increasing the production and exploitation of aquatic animals in the aquatic ecosystem without considering its relationship and balance with other parts of the ecosystem causes a wrong assessment of the real cost and benefits of these services More
Introduction: In general, increasing the production and exploitation of aquatic animals in the aquatic ecosystem without considering its relationship and balance with other parts of the ecosystem causes a wrong assessment of the real cost and benefits of these services to the environment and society, and in the future will have negative effects. The activities carried out in the aquaculture industry lead to a decrease in the quality of water and as a result the chemical balance in water is disturbed. On the other hand, the increase in metabolic activity in aquatic animals intensifies those effects. In the aquaculture industry, attention should be paid to quality control and monitoring methods. Knowing the basic conditions of the desired water body for the construction of breeding farms and predicting the future situation of the region based on the effluents entering is very necessary.Aim: In this study, the physicochemical conditions of Sisangan region were investigated for setting up a fish farm.Materials and Methods: In order to determine the state of sea water quality, water sample collected for one period to analyze pollution and physicochemical variables. After determining of the variables, the TRIX trophic index was calculated and the trophic conditions of the area were determined.Results: Measuring the physical parameters of water from 5 to 15 meters depth showed that the variables of temperature, electrical conductivity, salinity, oxygen and pH do not change much along the depth. The measurement of nutrients indicated that the total nitrogen in the sea in the study area varies from less than 0.1 mg/liter to 2.5 mg/liter. The amount of total phosphorus in the study range varies from less than the measuring limit of the device 0.003 mg/liter to 0.007 mg/liter. According to the measurements made in these studies, the result of calculating the TRIX index is an average numerical value of 2.3.Conclusion: The results of this study showed that the area is tropically oligotrophic and the water quality of the area is very good.
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Lake Choghakhor is a shallow ecologically and economically important water body in eastern part of Iran. During last decade Lake Choghakhor has been influenced by some man-made impacts such as water level fluctuation, agricultural discharge and fish (Cyprinids) introduc More
Lake Choghakhor is a shallow ecologically and economically important water body in eastern part of Iran. During last decade Lake Choghakhor has been influenced by some man-made impacts such as water level fluctuation, agricultural discharge and fish (Cyprinids) introduction causing a serious problem in its trophic states. So in this study water quality for physical, trophic state indicators, total phosphate, algal chlorophyll, Secchi disk transparency, biomass of macrobenthose (seasonal) was studied monthly between May 2004 to April 2005. Now submerged plants especially Myriophyllum spicatum have covered almost the entire lake and dense macrophyte beds (Polygonom amphibium), located on the south east end of the lake appear to act as a sink for these nutrients. Lake Choghakhor appeared to be in a macrophyte dominated clear water state with low TP (annual mean: 24± 15µg.l-1) and chlorophyll a (annual mean: 3±1.28 µg.l-1) and very high Secchi depth. Fish yeild potential was estimated according to TP model as 34.4 kg.ha-1, production value for macrobenthose was 4.7 mg DM m-2yr-1 and annual fish production obtained by macrobenthose was about 282 to 376 kg.ha-1yr-1.
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Gahar Lake is an unique high-mountain lake, "Paternoster" form with glacial origin. There isn’t any research on the ecology of the lake, so in order to assess trophic status of small and great Gahar lake for the first time using TLI, the present study was conducte More
Gahar Lake is an unique high-mountain lake, "Paternoster" form with glacial origin. There isn’t any research on the ecology of the lake, so in order to assess trophic status of small and great Gahar lake for the first time using TLI, the present study was conducted during a period of 1 year (except 3 months of ice period) from May 1389 to May 1390. Trophical parameters, Secchi depth (SD, transparency), chlorophyll a concentration and nutrients including Total Nitrates (TN) and Total Phosphorus (TP) was sampled monthly and zooplankton assemblage was measured. For statistical analysis of data in this study, we used the SPSS and Excel softwares. Based on the study of small Gahar lake, mean concentration of chlorophyll was 2.96µg.l-1, TN 801µg.l-1 and TP 25.3µg.l-1. In great Gahar lake, mean concentration of chlorophyll was 1.6µg.l-1, TN 976.5µg.l-1, TP 24.2µg.l-1 and mean value of secchi depth was 6.8m. According to TLI, the great Gahar Lake belongs to status of Mesotrophic level and the small Gahar Lake to Eutrophic level of the trophic scale.
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