Locomotor development of zebrafish (Danio rerio) under novel hydrodynamic conditions

The kinematics, neuromuscular control, and hydrodynamic aspects of normal locomotor activity in larval zebrafish have been extensively studied. Although locomotion depends heavily on the fluid properties of water, we have little knowledge of what sensory and developmental cues zebrafish larvae receive from their interaction with the fluid medium in which they grow. In this study, I manipulate the viscosity of water in which larvae grow until 5 and 7 days postfertilization (dpf) and record the kinematics of routine turns in their growth medium. Larvae are then transferred to a new medium of different viscosity and filmed again after short and long acclimation periods. Four hypotheses are tested: (1) larval kinematics are constrained by muscle activation patterns, (2) larval kinematics are guided by kinematic objectives, (3) routine turning control is independent of early locomotor experience, and (4) response to novel fluid environment is independent of developmental stage. The results indicate that a kinematic parameter, stage 1 angle, correlates with the kinematics of stage 1 while muscle activation patterns likely constrain stage 2. Development of this behavior is not dependent on locomotor experience both at 5 and 7 dpf, although the two age groups respond differently to increased viscosity.