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    Öğe
    Phytoplankton and Nutrient Variations in the Iranian Waters of the Caspian Sea (Guilan region) during 2003-2004
    (Central Fisheries Research Inst, 2014) Bagheri, Siamak; Türkoğlu, Muhammet; Abedini, Ali
    This study concentrated on temporal distribution and species composition of phytoplankton connected with physicochemical variations between January 2003 and November 2004 in the South Western Caspian Sea. During the study, 75 phytoplankton were distinguished in total and average phytoplankton densities in 2003 and 2004 were 1.47x10(5)+/- 6.05x 10(4)and 1.97x10(5)+/- 7.18x10(4) cells L-1, respectively. Contributions of diatoms (66.0% in 2003; 57.0% in 2004) and cyanophytes to total phytoplankton (17.0 in 2003; 36.0% in 2004) were higher than any other group. Diatoms Dactyliosolen fragilissimus and Thalassionema nitzschioides, and cyanophytes Oscillatoria sp. and Anabeanopsis raciborskii provided the biggest contributions to the total phytoplankton. Average DIN concentration in 2003 was higher (3.86 +/- 1.65 mu M) than the average in 2004 (3.37 +/- 1.13 mu M). However, average DIP concentration in 2003 was lower (1.45 +/- 1.37 mu M) than the average in 2004 (1.99 +/- 0.67 mu M). Average DIS concentration was two-fold higher than average DIN concentration. Average DIN: DIP without NH4 (2.66 +/- 1.66 in 2003; 1.69 +/- 1.17 in 2004) and DIS: DIP ratios (5.61 +/- 3.44 in 2003; 3.93 +/- 2.49 in 2004) were clearly lower than Redfield ratios. Nutrient ratios and phytoplankton densities revealed that system was eutrophic
  • [ X ]
    Öğe
    Phytoplankton Species Composition and Abundance in the Southwestern Caspian Sea
    (Foundation Environmental Protection & Research-Fepr, 2012) Bagheri, Siamak; Mansor, Mashhor; Türkoğlu, Muhammet; Makaremi, Marzieh; Omar, Wan Maznah Wan; Negarestan, Hossein
    This study, accomplished is focused on the spatial and temporal distribution and species composition of phytoplankton in the southwestern Caspian Sea between January 2008 and December 2008. Samples were collected from 11 stations along three transects known as Lisar, Anzali and Sefidrood. This study identified 43 phytoplankton species comprised of diatoms (25 species), dinoflagellates (7 species), chlorophytes (6 species), cyanophytes (4 species), and euglenoids (1 species) were identified. The study showed, diatom Dactyliosolen fragilissimus and the dinofllagelate Prorocentrum cordatum numerically dominate the southwestern Caspian Sea. The annual average phytoplankton density was calculated as 2.35E+04 +/- 1.63E+04 Cell L-1, with the maximum value recorded in the winter (4.50E+04 +/- 3.90E+04 Cell L-1). Diatoms were dominant during the autumn and winter (77.0% and 96.0%, respectively), while dinoflagellates were prevalent during the spring and summer (89.0% and 86.0%, respectively). The annual average chlorophyll a was calculated as 9.26 +/- 3.54 mu g L-1, with the maximum values were recorded in the winter (16.9 +/- 5.60 mu g L-1). This is supported by the Spearman rank correlation result between phytoplankton abundance and chlorophyll a (r=0.551). The high phytoplankton cell density and chlorophyll a concentration coincided with the poor species composition.
  • Küçük Resim
    Öğe
    Temporal distribution of phytoplankton in the south-western Caspian Sea during 2009-2010: a comparison with previous surveys
    (Cambridge Univ Press, 2012) Bagheri, Siamak; Mansor, Mashhor; Türkoğlu, Muhammet; Makaremi, Marzieh; Babaei, Hadi
    This study focuses on spatial and temporal distribution and species composition of phytoplankton in the south-western Caspian Sea between July 2009 and March 2010. Samples were collected from 11 stations along three transects: Lisar, Anzali and Sefidrood. Among 44 identified phytoplankton species, diatoms (70.2%) and cyanophytes (25.0%) were dominant. The average phytoplankton abundance was calculated as 1.085E + 05 cells l(-1). Among the phytoplankton groups, diatom density was higher (70.2%) than two out of three of total abundance in density of 1.085E + 05 cells l(-1). Cyanophytes were the second important group (25.0%) contributing to total phytoplankton. Dinoflagellates, chlorophytes and euglenoids were other contributors to total phytoplankton. Diatoms Dactyliosolen fragilissimus and Skeletonema costatum and cyanophyte Oscillatoria sp. numerically dominated in the system. There were major changes in phytoplankton composition and average phytoplankton density was higher than those documented in 1996-1997 and 2005. The average concentrations of dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP) and dissolved inorganic silicate were 14.5 +/- 6.32, 1.14 +/- 0.44 and 5.10 +/- 3.98 mu M, respectively, and these concentrations were strikingly high. Increases in DIN and DIP concentrations were more than twofold compared to recorded values during the last 2 decades due to the eutrophication. Fluctuations in nutrients played an important role in the variation of phytoplankton composition and abundance. Chlorophyll-a concentrations varied between 3.22 and 16.1 mu g l(-1) and there was a significant increase in chlorophyll-a (8.13 +/- 5.72 mu g l(-1)) compared to the values in 1996-1997 (1.44 +/- 1.48 mu g l(-1)), 2001 (2.62 +/- 1.48 mu g l(-1)) and 2005 (2.14 +/- 1.94 mu g l(-1)).