Akademik Veri Yönetim Sistemi
Turkish Journal Of Biology, cilt.33, ss.335-340, 2008 (SCI-Expanded)
The aim of this study was to investigate seasonal
variability in the growth and size structure of dominant phytoplankton species
in Buyukcekmece Reservoir, and to determine the environmental factors that
affect morphological plasticity in those dominant species. In total, 78 taxa
from 8 algal divisions were identified. Bacillariophyta and Chlorophyta were
the most important divisions with respect to species number, but cryptomonads Plagioselmis
nannoplanctica (Skuja) Novarino, Lucas, and Morrall, and a Cryptomonas sp.
were dominant in terms of density and biomass. P. nannoplanctica was the
major contributor of biomass in the reservoir. A significant difference in Plagioselmis
species biovolume was observed between winter-early spring and summer. A
significant negative correlation was observed between its seasonal size
structure and abundance. During winter (December 2004-April 2005) nutrient
values were higher than during autumn (October-Novermber 2005) and P.
nannoplanctica had maximum cell size (17.5 μm x 10 μm; biovolume: 589.5 μm3),
but its abundance was very low (< 6 cells × 103 l−1). The minimum
surface:volume ratio (SA/V: 0.87) was recorded in this period. Among the measured
environmental factors, water temperature was the only parameter that had a
statistically significant negative relationship (R2: 0.635; P < 0.01) with P.
nannoplanctica cell size. The results indicate that seasonal changes in
cryptomonad size structure were controlled by water temperature.