Phytoplankton abundance, biomass and species composition of the Caspian Sea were evaluated by using samples collected from the Iranian (southern Caspian Sea) and southern Kazakhstan (eastern Caspian Sea) surface waters in March 2001. A total of 45 taxa were found in the samples (20 diatoms, 17 dinoflagellates and 8 others). Abundance and biomass of diatoms were high at the eastern stations, while dinoflagellates were dominant in terms of both biomass and abundance in the southern region. Average abundance and biomass were 40 000 ± 35 000 cell l )1 and 580 ± 690 lg l )1 . The mean biomass value found here for the Middle and southern Caspian Sea in March are difficult to compare with the past due to limited information, but seems higher than previously registered values. Higher chlorophyll values were also apparent from the SeaWIFS images in 2001 compared to those in 1998. This is suggested to be due to decreased grazing of phytoplankton by zooplankton which is voraciously preyed by the recent invasive ctenophore Mnemiopsis leidyi.

Species composition, abundance, and biomass of micro-(>15 m) and nano-(<15 m) phytoplankton were studied in the western and eastern Black Sea during March-April and October 1995. A total of 142 species were identified, of which >50% were dinoflagellates. Abundance and biomass values were lower during the March-April period (average 129 28 thousand cells l 1 and 330 124 g l 1) than during the October period (average 364 161 thousand cells l 1 and 1794 515 g l 1) and compared with previous investigations. Values for the north-westerly region were higher than for the southerly areas, probably owing to effects of the Danube river, but were much lower than previously reported, possibly indicating improved ecological conditions. In March-April, dinoflagellates (mainly Heterocapsa triquetra and Scrippsiella trochoideum) were the most important groups, whereas, in October, diatoms (mainly Pseudosolenia calcar-avis) and coccolithophores (Emiliania huxleyi) were dominant. Nanophytoplankton constituted 57% and 84% of total abundance and 8% and 3% of total biomass in spring and autumn, respectively. Microphytoplankton were dominant in the western Black Sea, whilst nanophytoplankton were dominant in the eastern region in spring.

In this work, it was analysed the effect of different channel width on performance of PEM fuel cell. Current density were measured on the single cells of parallel flow fields that has 25 cm² active layer, using three different kinds of channel width. The cell width and the channel height remain constant. The results show that increasing the channel width while the cell width remains constant decreases the current density.

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