Ecological inferences on invasive carp survival using hydrodynamics and egg drift models

Area of Science:

• Ichthyology
• River Ecology
• Computational Fluid Dynamics

Background:

• Invasive carp species in North America, including bighead, silver, black, and grass carp, are economically important food sources in China.
• Carp egg survival is significantly influenced by river hydrodynamics during their drifting stage.

Purpose of the Study:

• To explore carp egg-drift dynamics using computational fluid dynamics (CFD) to infer potential egg settling zones in the Lower Missouri River.
• To compare hydrodynamic-inferred settling zones with those predicted by an egg-drift transport model.

Main Methods:

• Simulated river flow characteristics using CFD models for an 8-km reach of the Lower Missouri River at four different discharges.
• Analyzed spatial distributions of flow velocity, depth, turbulence kinetic energy (TKE), and TKE dissipation rate.
• Determined potential egg settling zones using criteria based on shear velocity, vertical turbulence intensity, and Rouse number.

Main Results:

• CFD simulations revealed heterogeneous spatial distributions of hydrodynamic parameters.
• Hydrodynamic inference identified potential egg settling zones, but egg-drifting paths are necessary for improved prediction accuracy.
• Simulated river turbulence levels were below the laboratory-identified threshold that could pose a threat to carp eggs.

Conclusions:

• Hydrodynamic inference provides a useful assessment of potential carp egg settling areas.
• Integrating egg-drifting paths with hydrodynamic data enhances the accuracy of predicting carp egg survival zones.
• Lower Missouri River turbulence is unlikely to be a significant mortality factor for drifting carp eggs.