Quantification Of The Microscale Dynamics Of Live Bighead Carp Egg Settlement In Static Water

The survival of bighead carp is threatened by the construction and operation of river engineering projects. In order to guide future reservoir regulation to suitably incorporate the ecological requirements of fish, it is important to understand fish egg settlement in static water. Therefore, video capture technology and wavelet analysis in experiments were used to observe and analyze the microscale processes of live bighead carp egg settlement in static water. The study examined the temporal variations in the egg attributes and revealed microscale fluctuations in the trajectories of eggs and changes in settling velocity. The egg settling velocities were divided into both mean and fluctuating components. Both components indicated that bighead carp eggs had different settling velocities depending on the stage of development. Settling velocity is dominated by hydrodynamic drag in the first 22 min post-fertilization, with a rapid increase in velocity through time, followed by a decrease in velocity and finally a stable value of 0.75 cm/s. The periodicity of the fluctuating component may indicate the importance of the egg inner structure or even the development of the embryo to settling velocity. This work strengthens the understanding of bighead carp egg settlement in static water and provides a clear indication to river engineers and managers of the need to promote the successful drift of bighead carp eggs in rivers to ensure the maintenance of their populations.