Seasonal species diversity and abundance of phytoplankton from the southwestern Caspian Sea

Abstract

In the present investigation, we aimed to study diversity and cell abundance of phytoplankton in the southwest of the Caspian Sea. This survey included 4 transects and 12 stations. A total of 48 samples were collected during spring 2012 and spring 2013. Finally, 72 species of phytoplankton were identified including phyla Diatoms (29 species), Chlorophyta (17 species), Pyrrophyta (16 species), Cyanophyta (6 species), and Euglenophyta (4 species). The total average of cell abundance was approximately 43.55 ± 5.10 9 104 cells/ m 3. The number of recorded species in spring, summer, autumn, and winter was 46, 50, 41 and 39, respectively. Diatoms had the highest species diversity and cell abundance in winter related to Thalassionema nitzschiodes at a depth of 10 m. Seasonal changes in diversity of phytoplankton significantly differed, showing maximum in autumn with high diversity index (2.532) and minimum in spring (2.201) on Shannon Diversity Index. Finally, the quality of water is classified according to this index in the middle level.

Physical-Chemical Factors Affecting Diversity and Distribution of Blue-green Algae in the Southern Caspian

“…It is lower than the maximum cyanobacteria number of 80.18× 10 5 cells1 -1 that was recorded, so far, in the Southern Caspian (Mahdavi et al, 2014). Species of O. limosa was the most frequent species across the entire southern coast of the Caspian Sea in the previous study during summer (Tahami et al, 2012;Mahdavi et al, 2014;Heydari et al, 2018). It was because the first stations of transects A, B and D were located in estuaries of the rivers, where the salinity are low and the pollution are high, created a good conditions for cyanobacteria growth (Vincent, 2009).…”

“…In the Southern Caspian, blue-green algae contribute only slightly to the algological composition from 8 to 17% (Tahami et al, 2012;Heydari et al 2018), in contrast to the northern Caspian, where cyanophytes can take a leading position both the cell number and biomass (Abdurakhmanov et al, 2010). The reason for that is, on the one hand, the higher water salinity in the Southern Caspian and, on the other hand, the higher biogenic element content because of anthropogenic press in waters of the north Caspian (Kosarev, 2005).…”

“…In Iran, 198 intraspecific taxa from the different aquatic ecosystems were reported (Zarei Darki, 2011). In the Caspian Sea, according to the investigated data, 102 species of Cyanophyta were totally identified (Heydari et al, 2018). The Iranian researchers conducted the several surveys on the study of cyanobacterial flora including their seasonal distribution, cell abundance and biomass in the Southern part of the Caspian Sea (Golaghai et al, 2010;Emtiazjoo et al, 2012;Pourghola et al, 2014;Heydari et al, 2018).…”

“…In the Caspian Sea, according to the investigated data, 102 species of Cyanophyta were totally identified (Heydari et al, 2018). The Iranian researchers conducted the several surveys on the study of cyanobacterial flora including their seasonal distribution, cell abundance and biomass in the Southern part of the Caspian Sea (Golaghai et al, 2010;Emtiazjoo et al, 2012;Pourghola et al, 2014;Heydari et al, 2018). Furthermore, Emtiazjoo et al Blue-green algae were prepared and recognized according to standard methods men-tioned in monographs and identification keys (Proshkina-Lavrenko, 1974;Kondratyeva, 1968;Komarek and Anagnostidis, 1999; Komárek and Hauer, 2009).…”

Viromes of Coastal Waters of the North Caspian Sea: Initial Assessment of Diversity and Functional Potential

“…SUR and MSC samples were dominated by viruses closely related to known cyanophages of unicellular cyanobacteria, mainly Synechococcus sp. The dominance of cyanophages in these samples may be a consequence of increased cyanobacterial content because of the introduction of freshwater phytoplankton by the Ural River and their more active growth in the shallow, and hence warmer, water of the Northern Caspian Sea [78].…”