Free-swimming behaviour of Acartia clausi (Copepoda: Calanoida) under turbulent water movement

Abstract

The free-swimming behaviour of Acartia clausi under controlled food and turbulence conditions has been studied in the laboratory. Three experimental conditions were tested: Calm (no turbulence), Low Turbulence (epsilon: horizontal: 1.1 mm2 s-3; vertical: 0.7 mm2 s-3), and High Turbulence (epsilon: horizontal: 4.9 mm2 s-3; vertical: 5.4 mm2 s-3). Feeding activity, as estimated by the frequency of feeding bouts, increased in turbulent water motion by a factor of 2.7. Turbulence also induced an increase in the frequency of and velocity displayed in jumping behaviour (by 1.7 times for frequency of bouts, by about 1.9 for jump velocity). These results confirm previous theoretical and experimental hypotheses about the importance of small-scale turbulence on zooplankton activity and dynamics