The Swimming Behavior of the Calanoid Copepod Calanus sinicus Under Different Food Concentrations

Calanus sinicus is a calanoid copepod and dominant zooplankton species in the coastal waters of the western North Pacific rim. We examined the effects of different food concentrations on the swimming behavior of this species. Adults were video-recorded at 30 frames/s using video equipment that allowed us to follow each freely swimming individual continuously in 1L containers (10 x 10 x 10 cm) with 30 PSU salinity filtered seawater at 20 degrees C. Several behavioral parameters such as swimming trajectories and speed showed distinct changes under different food conditions. The dynamics of swimming states were assessed by the statistical properties of their trajectories. Slow swimming was generally the dominant behavior. Swimming path trajectory decreased at high food concentrations and swimming path entropy decreased when the food concentrations increased.