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Vol. 52, 2013
Ciliate (Euplotes
sp.) predation by Pseudodiaptomus
annandalei (Copepoda:
Calanoida) and the effects of mono-algal and pluri-algal diets
Raunak
Dhanker1, Ram Kumar2, Li-Chun Tseng1
and Jiang-Shiou Hwang1*
1Institute of Marine Biology, National Taiwan Ocean University, Keelung 20224 Taiwan
2Centre for Environmental Sciences, Central University of Bihar, Patna 110 0014, Bihar, India
Abstract
Background: Pseudodiaptomus annandalei is an estuarine species
and being cultured as live feed for grouper fish larvae and other
planktivores. We examined the predation behavior of P. annandalei adults when preying
on ciliated protists (Euplotes
sp.) and the effects of mono- and pluri-algal diets on ciliate
predation by P. annandalei
under laboratory conditions. The algal food comprised the pigmented
flagellate Isochrysis galbana (4 ~ 5 μm) and Tetraselmis chui (17 ~ 20 μm).
Results: Males and females of P. annandalei consumed 8 ~ 15
ciliate cells/h. The probability of ciliate ingestion following an
attack was a direct function of the copepod's hunger level. Conversely,
the probability of prey rejection after capture was a negative function
of the copepod's hunger level. Starved and poorly fed females showed a
significantly lower rate of prey rejection compared to similarly
treated males. The duration of handling a ciliate prey did not
significantly differ between males and females of P. annandalei. Starved copepods
spent less
time handling a ciliate prey than fed copepods. Prey ingestion rates
showed a negative relation with the feeding duration, whereas the prey
rejection rate increased as the feeding duration increased. The ciliate
consumption rate of P. annandalei
was significantly lower in the presence of mixed algae. Neither I. galbana nor T. chui alone had any significant
effect on ciliate consumption by P.
annandalei.
Conclusions: The results confirmed
that P. annandalei ingests
bacterivorous heterotrophic protists even in the presence of
autotrophic protists. Therefore, our results point to the role of P. annandalei in the transfer of
microbial carbon to the classical food chain in estuarine and brackish
water ecosystems.
Key words: Copepod, Ciliate, Algal prey,
Feeding, Predation, Hunger level.
*Correspondence: E-mail: jshwang@mail.ntou.edu.tw
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