Basic HTML Version
International Journal of Marine Science 2013, Vol.3, No.15, 121-127
http://ijms.sophiapublisher.com
123
minimal in September at st.4, and in August~
September at st.5, that coincided with the minimal
total phytoplankton biomass (20~30 mgС/m
3
), i.e.,
with the local prey deficiency. Maximums were
registered in November at st.4 and in May at st.5.
Figure 2 Seasonal dynamics of the microzooplankton grazing
on phytoplankton (1), the ratio of grazing to phytoplankton
growth rate (2), and phytoplankton biomass (3) in the surface
waters of the Sevastopol bay (A), Quarantine bay (B) and in the
open coastal waters near Kruglaya bay (C) in 2010
It is generally accepted that water temperature
influences both phytoplankton growth and grazing
activity of zooplankton. Therefore, all data on the
microzooplankton grazing impact that has been
generated for 2006~2007 and 2010 was divided into
Figure 3 Seasonal dynamics of the microzooplankton grazing
on phytoplankton (1), the ratio of grazing to phytoplankton
growth rate (2), and phytoplankton biomass (3) in the surface
waters near Katsiveli in 2010: A – St. 4, B – St. 5
two sets. One dataset comprised the cold-season
(November~April) estimates obtained when the
average temperature of the sea was 11
℃
(± 2
℃
), and
the other represented the warm season (May~October)
when the seawater temperature for all stations and for
years was averaged 23
℃
(± 4
℃
). Analysis of the data
has shown that in 2006 and 2007, the specific rate of
microzooplankton grazing on phytoplankton during
the warm season made 1.19 d
-1
on the average for all
sampling stations, being practically twice as large as
that during the cold season (Table 1). In the warm
season of 2010, it was estimated 0.52 d
-1
that did not
reliably differ from the cold season. The shortage of
prey (low phytoplankton biomass) in the warm
months of 2010 and, probably, the changes in the
phytoplankton taxonomic structure (the dominance of
dinoflagellates) have decreased the predatory control
by microzooplankton. Then, logarithmic dependence
between the specific rate of phytoplankton
consumption by microzooplankton and chlorophyll-
а
concentration in the plankton was determined (Figure 4).