Swimming and escape behavior
of copepod nauplii: implications for predator-prey interactions among
copepods
J. Titelman-2001
Marine Ecology Progress Series, 213 : 203-213
(from Current Contents)
Abstract:
This study focuses on how prey behavior may affect
predation risk through encounter rates and the escape success of the prey
given an encounter. Temora longicornis nauplii require stronger hydrodynamic
signals to elicit escape than Acartia tonsa nauplii (critical fluid
deformation rates, Delta* of 2.8 to 4.0 and 1.2 to 2.5 s(-1), respectively)
suggesting that T. longicornis may be more susceptible to predation.
Quantification of naupliar motility behavior and subsequent estimation of
the hydrodynamic signals which the nauplii generate suggest that an adult
female Centropages typicus may detect: an A. tonsa nauplius at a greater
distance than a similarly sized T. longicornis nauplius. Observations of
attacks of free swimming C. typicus and the naupliar prey confirmed that T.
longicornis is poorer at detecting predators than A. tonsa, and that the
same predator detects A. tonsa at a greater distance than it detects T.
longicornis nauplii (2.37 +/- 1.46 and 0.34 +/- 0.18 mm, respectively). The
combined effect of prey motility and escape behavior was tested by offering
C. typicus females the 2 prey species alone and in mixtures. Clearance rates
on T. longicornis (442 +/- 125 ml female (-1) d(-1)) were ca 3-fold that on
A. tonsa nauplii (146 +/- 35 ml female (-1) d(-1)) in both single species
and mixed treatments. While the low profile motility behavior of T.
longicornis appears to reduce encounter rates, its post encounter (i.e.,
escape) behavior is less effective. In contrast, the behavior of A. tonsa
acts predominantly at the post-encounter stage where its sensitivity to
hydrodynamic signals (i.e., low Delta*) effectively compensates for the high
predator encounter rate generated by its motility.
(Danish Inst Fisheries Res, Dept Marine & Coastal
Ecol, Kavalergarden 6, Charlottenlund 2920, Denmark, e-mail: jti@dfu.min.dk)