جستجوی مقالات مرتبط با کلیدواژه "trophy" در نشریات گروه "کشاورزی"

Hassanlou Wetland is one of the natural attractions of West Azarbaijan Province which is registered in the list of international wetlands in the Ramsar Convention. After the construction of Hassanlou dam the depth of the wetland increased, the amount of salts decreased and as a result, the wetland became more of a lake behind the dam. The change in conditions due to the construction of the dam has caused the wetland ecosystem to undergo changes. Since Hassanlou Dam Lake has a high capacity for growing of invasive aquatic plant species, samples of plant species and water from the lake were collected to identify invasive species and also to determine the water trophy. The results of the study showed the presence of four invasive plant taxa including Stuckenia pectinata, Potamogeton perfoliatus, Cerathophyllum sp., and Najas marina. Calculations based on the Carlson trophy index indicated that the water of this lake is eutrophic. The cause of this issue can be attributed to the washing of agricultural runoff containing manure of cattle that graze around the lake. High trophy has increased the density of invasive aquatic plant species, which is considered a serious threat to lives of native plant species and fisheries. To remove these unwanted plants and control their population, it is recommended to use physical, mechanical, biological and chemical control methods. In most cases, physical and mechanical methods to cut these plants are not efficient and it is appropriate to use approved herbicides that target a specific plant.

Today, the environmental and habitat importance of wetlands has been revealed for all societies and special attention is paid to urban wetlands for recreation, boating, fishing, hunting, and aquaculture. One of the most important natural-man-made wetlands of Gilan province is located in Lahijan city and is called Lahijan pool. The objectives of this research were to investigate and identify the phytoplankton, zooplankton, and aquatic communities of this wetland in five stations and during four seasons. From the fall of 2017 to the summer of 2018 in this habitat, which has an area of ​​11 hectares and a depth of less than 4 meters, planktons and crustaceans were sampled by standard methods and the results showed that the average water surface temperature was 17.16 ± 7.3 degrees Celsius, dissolved oxygen The water level was 7.05 milligrams per liter, the pH of the water depth was 3.85, and the average percentage of organic matter was 3.29 ± 1.26. Phytoplanktons was identified in 7 branches and 29 genera, and in terms of annual abundance, blue-green algae ranked first with 48% and Bacillophyta ranked second with 43%. 4 groups and 18 species of zooplankton have been identified in this ecosystem, of which pinnipeds were the most abundant with 35%. Oligochaeta and Chironomide larvae were the only identified benthic groups that had 167 numbers per square meter. In general, the species diversity of plankton and crustaceans in this wetland was low, but the density of the present species was determined to be relatively high. According to the physicochemical characteristics of the water and the planktonic and benthic species of this lagoon, it should be considered a eutrophic ecosystem, but of course, the input and output of water and the aeration that takes place in it can create the conditions for the breeding of some tropical fish or crabs. Make fresh water possible.

Over the past years, eutrophication due to human activities has been recognized as a major ecological problem for the coastal areas, which in turn leads to significant changes in physicochemical and biological factors. The aim of the present study was to determine the eutrophication status of the Gorgan Bay, which was evaluated using the Carlson index as one of the efficient methods for assessing the eutrophication status of water bodies. The Gorgan Bay is located in the southeast of the Caspian Sea. The sampling was carried out in 23 stations with three replications seasonally from summer 2018 to spring 2019. Nitrate, phosphate, chlorophyll α, depth, and transparency were measured in each sample. Carlson's index in terms of chlorophyll α showed that the bay is in the eutrophic status in three seasons including summer, autumn, and winter (with the numbers 53.48, 53.69, and 53.67, respectively), and the mesotrophic status in spring (with the number 42.75). In terms of phosphate concentration, the bay was eutrophic in autumn and winter, and in summer (69.22 and 55.17) and oligotroph in spring (26.75 and 35.30), while in terms of transparency the bay was categorized as eutrophic in all seasons (63.33, 61.61, 69.93 and 61.58, respectively). In general, the results showed that the bay is in the range of mesotrophic to eutrophic status and therefore, more conservation management of this unique ecosystem is essential.

Determination of trophic status is one of the methods for assessing ecological balance of wetland ecosystems, because sustainability and productivity based on these unique ecosystems require proper monitoring and control of their environmental conditions. Therefore, biological and ecological studies are necessary before any activity is established. Tanudar Wetland with an area of 1000 hectares is one of the largest wetlands of Lorestan Province, 10 km northwest of Dorood. In this study, physical and chemical characteristics of Tondar wetland sampling were used to evaluate the nutritional status of Carlson (TSI) based on total phosphate (TP), total nitrogen (TN) and phosphorus to nitrogen (PN) Sampling of Tanudar wetland was used in summer of 2019. The results showed that based on the Carlson Trophic Index (TSI), trophic wetland Tanudar level is in eutrophic conditions. wetland Tanudar to its location, natural conditions and hydrological conditions, the is mainly drained from the highlands of Silakhor plain and tira River Dorood, Therefore, any upstream loading such as orchard development, diversified recreational harvests in the river, increased levels of dark river water pollution caused by municipal, industrial wastewater, and point source pollution sources such as warm-water fish ponds have crossed the Tanudar wetland. And it wound deeper on the current unstable body. Therefore, in the current conditions, the quantitative and qualitative provision of the wetland ecological right of the wetland is one of the most obvious requirements and management issues of the wetland.

The present study was carried out in Karun 4 Dam lake, Chaharmahal-v-Bakhtiari province with the aim of tropic determination and assessing some of the relationships between physical, chemical and biological properties of water from March, 2011 to 2012. Three stations were selected in the dam: one station near the dam wall and two stations at the entrance of Urmand and Bazoft rivers, respectively. Some of physicochemical properties of water including temperature, turbidity, hardness, temperature, pH, dissolved oxygen, biological oxygen demand, chemical oxygen demand, total soluble solids, total suspended solids, nitrates and phosphoric acid, as well as biological properties such as phytoplankton identification and counting, chlorophyll a were monthly evaluated. Based on the present results, 5 branches and 30 species of phytoplankton were identified with the most frequency of Bacillariophyta (17 species), Chlorophyta (6 species), Chrysophyta (4 species), Dinophyta (2 species), and Cyanophyta (1 species), respectively. The maximum and minimum chlorophyll a content were obtained in June (4.9 μg L-1) and its minimum in February (2.1 μg L-1), respectively. Findings of the current research showed that chlorophyll a concentration correlates with the temperature, while no correlation was found with the suspended solids (P> 0.01). On the other hand, chlorophyll a content and phytoplankton diversity showed a significant negative correlation with transparency, total nitrogen, and total phosphorus (P <0.01). The highest and lowest richness index was observed in summer (0.061117) and in autumn (0.058), respectively. The Simpson species diversity index was also reached to the highest and lowest value in spring (0.98889) and autumn (0.9905), respectively.

The present study was carried out in Karun 4 Dam lake, Chaharmahal-v-Bakhtiari province with the aim of tropic determination and assessing some of the relationships between physical, chemical and biological properties of water from March, 2011 to 2012. Three stations were selected in the dam: one station near the dam wall and two stations at the entrance of Urmand and Bazoft rivers, respectively. Some of physicochemical properties of water including temperature, turbidity, hardness, temperature, pH, dissolved oxygen, biological oxygen demand, chemical oxygen demand, total soluble solids, total suspended solids, nitrates and phosphoric acid, as well as biological properties such as phytoplankton identification and counting, chlorophyll a were monthly evaluated. Based on the present results, 5 branches and 30 species of phytoplankton were identified with the most frequency of Bacillariophyta (17 species), Chlorophyta (6 species), Chrysophyta (4 species), Dinophyta (2 species), and Cyanophyta (1 species), respectively. The maximum and minimum chlorophyll a content were obtained in June (4.9 μg L-1) and its minimum in February (2.1 μg L-1), respectively. Findings of the current research showed that chlorophyll a concentration correlates with the temperature, while no correlation was found with the suspended solids (P> 0.01). On the other hand, chlorophyll a content and phytoplankton diversity showed a significant negative correlation with transparency, total nitrogen, and total phosphorus (P <0.01). The highest and lowest richness index was observed in summer (0.061117) and in autumn (0.058), respectively. The Simpson species diversity index was also reached to the highest and lowest value in spring (0.98889) and autumn (0.9905), respectively.

One of the phenomena that lead to the deterioration of surface water quality specially reservoirs is eutrophication caused by nutrients increasing like nitrates and phosphates in water resources. In this study, nitrate, phosphate and other factors such as temperature, turbidity, biological oxygen demand were measured monthly in six stations during the years 1393-1394 and the status of eutrophication in Kani-Brazan wetland and its influencing factors were investigated. The concentration of phosphorus and nitrogen of the wetland water were classified to the fourth trophic level of Oligotroph, Mezotroph, Eutroph and Hypertroph, and by comparison with international standards of Nuremberg, wetland eutrophication status was determined. Results showed that the average annual value of the water temperature was 17.4°C, pH=8.02, turbidity=16.03 and BOD was 5.8 (max=8.2 in spring and min=6.9 in summer). The values of all forms of nitrogen varied between 0.4 to 0.8 mg/lit indicating the trophic health of the wetland. The amont of phosphorus in wetland was upper than the limit of 0.03 mg/lit indicated that continue of this process could have consequences for the wetland ecosystem and affects attractive aquatic environment greatly.

This study focused on phytoplankton structure, a biotic limiting factors in phytoplankton bloom at the 5 stations between 2013 and 2014 in the Chitgar Lake. This study identified 35 phytoplankton taxa comprised of Diatoms (12 genus), Chlorophyta (15 genus), Cyanophyta (4 genus), dinoflagellates (2 genus) and chrysophytes (1 genus) in the lake. The finding showed, the Diatom abundance dominate (average of 2060000 ± 230000 cells.l-1) in the Chitgar Lake. The annual average phytoplankton abundance was calculated as 2550000± 304000, with the maximum value recorded in February 2013 (4400000 ± 450000 cell. l-1). The PCA analysis displayed, the Diatoms Cyclotella sp., Achnanthes sp. and Chrysophta Dinobryon sp. were dominated in the study period. Based on the CCA analyses, total nitrogen and water temperature were the significant parameters to increase Cyanophyta and Dinoflagellata abundance in the Chitgar Lake. In overall, the lowest phytoplankton abundance recorded in the Chitgar Lake as compared with other lakes which is an Oligotrophic with the latest trophy state lake.

This study focused on zooplankton structure, biodiversity, relationship between a biotic parameters and zooplankton variation, and trophy state of the Persian Gulf Martyrs Lake (Chitgar-Tehran). Based on the lake condition, samples were collected by Juday net at the 5 stations between 2013 and 2014. This study identified 36 zooplankton taxa comprised of Arthropoda (6 genus), Protozoa (6 genus), Rotatoria (20 genus), Nematoda (1 genus), Gastrotricha (2 genus) and Oligochaeta (1 genus). Furthermore, the first record of the freshwater jellyfish Craspedacusta sp. in Iran, with size group of 15-20 mm in diameter in September is reported in the Chitgar lake. The Rotatoria abundance average was measured 61 ±18 ind.l-1 in the lake. The Nematoda, Gastrotricha and Oligochaeta taxa were measured the lowest abundance (

Amirkelaye international wetland, with an area of 935 acres is located in Gilan province. Agricultural runoffs, water withdraws for agricultural purpose and plants growing, especially submerged and marginal plants are of the main threatening factors in this wetland which reduce its surface and therefore it is necessary to determine the trophy status in the case of adverse circumstances, the reclamation measures can be done for it. The research was made from autumn 1392 to summer 1393 in order to check the status of Amirkelaye wetland trophy. Sampling was done from 6 stations during four seasons, and in which trophic state index (TSI) was examined using 4 parameters: total phosphorus (TP), total nitrogen (TN), the depth of Secchi disk (SD) and chlorophyll (chl-a). According to TSI index, Amirkelaye wetland is in the most critical state in the terms of SD parameter compared to TP, TN and chl-A parameters and in a better state in terms of chl-A parameter compared to TP, TN, and SD parameters. According to the statistical analysis, the average amount of total nitrogen in winter and summer was lowest and highest, respectively. The average amount of phosphate was observed as highest and lowest in winter and autumn, respectively. Average amount of chlorophyll A was highest in summer, but the other three seasons together in terms of the amount of chlorophyll A were not significantly different (P> 0.05). Average depth of Secchi disk was found the lowest and highest in summer and winter, respectively. Using Duncan statistical test, none of the variables of chlorophyll A, total nitrogen, total phosphorus and depth of Secchi disk at various stations were significantly different (P> 0.05). The results showed that in the autumn and winter, Amirkelaye wetland was in the Mesotrophic state and in the spring due to agricultural runoffs entering was in acute Mesotrophic state. In the summer, due to increased agricultural runoffs entering and the hot weather, it was in the Eutrophic state.