School of Engineering and Science - Jacobs University

CHAPTER IV
Gyrodinium dominans (Figure 1a) grew at a mean rate of 0.32 d -1 during the three days
in the single predator treatment and continuously increased its growth rate from 0.21 to
0.42 d -1 (Figure 2a). The specific ingestion of the dinoflagellates decreased from 0.9 to
0.5 cells predator -1 d -1 (mean 0.7 cells predator -1 d -1 ) during the experiment. With a
mean grazing rate of 0.48 d -1 (0.44-0.57 d -1 ) G. dominan’s consumption averaged the
production of S. trochoidea (mean growth rate 0.45 d -1 ) and the predator was not able to
graze down its prey substantially during the experiment. Mean predator specific
filtration rates recorded for G. dominans ranged between 0.31 and
0.59 mL µg predator -1 d -1 (mean value 0.49 mL µg predator -1 d -1 ).
Figure 2: Growth rates [d -1 ] of both predators (2a: Gyrodinium dominans, 2b: Favella ehrenbergii)
preying on Scrippsiella trochoidea in single predator and two predator treatments after 24, 48 and 72
hours of incubation; calculated for 24 hour intervals. Error bars correspond to one standard deviation, n =
4. Significant differences are marked by asterisk (two-tailed t-tests).
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