جستجوی مقالات مرتبط با کلیدواژه « diatoma » در نشریات گروه « محیط زیست »

This study aimed to identify and recognize the changes and the temporal and spatial dynamics of diatom communities in the Southern Caspian Sea, in the Southern Caspian Sea, in 2010- 2011 during spring, summer, autumn and winter, in 32 study sites from 8 transects Astara, Anzali, Sefidrood, Tonekabon, Noshahr, Babolsar, Amirabad, Turkaman and the south coast of the Caspian Sea. In each transect, have choosen 5 stations and different depths of 5 m, 10 m, 20 m, 50 m and 100 m were determined sampling was done seasonally from zero depth (level) and 10 m, 20 m, 50 m and 100 m depth by Niskin sampler. A total of 87 species belong to diatoms. Most species of diatoms was seen in autumn (64 species) and then in spring (48 species). The dominant species include Pseudonitzschia seriata¡ Rhizosolenia fragilissima, Stephanodiscos sp., Melosira varians ¡Nitzschia acicularis, Cyclotella menenghiniana. The highest species diversity was in the spring and then gradually in summer, autumn and winter decreased due to Shannon index in the spring in the western region (0.96) and minimum Shannon index was seen in autumn in western region (0.47).

Diatoma De Candolle is common algae flora in equatic ecosystem. Epilithic, Epipelic and Epiphytic population are the best indicator for water quality.
In this study, samples were taken on monthly, of 6 different station of rock, sediment and plant surface. Physicochemical parameters such as temperature , pH, Electrical Counductivity and Dissolved Oxygen were insitu measured in site and Biological Oxygen Demand and Chemical Oxygen Demand were measured in laboratory. Diatoms identify on the basis of morphological characters of the silica cell wall.
Findings: species from Diatoma De Candolle in Jajrood river were identified consist of: Diatoma anceps (Ehr.) Kirchn. Diatoma ehrenbergii Kutz. Diatoma mesodon (Ehr.) Kutz. Diatoma tenuis C. A. Agardh. Diatoma vulgare Var. breve Grun. Diatoma vulgare Var. linearis V. H. Diatoma vulgaris Bory.
Discussion and Counclusion: Physicochemical factors such as BOD and COD increases and the water pollution index, are down the river is significant pollution increases. Diatoms counting showed diatoms density down the river to increase. Two-way ANOVA showed a significant correlation is between increased diatoms density and increased pollution.