Effect of turbulence on the mortality of zebra mussel veligers

Abstract

Small-scale turbulence can increase the mortality of zebra mussel (Dreissena polymorpha) veligers. Laboratory experiments were conducted in which veligers were subjected to turbulence due to a bubble plume and the rate of dissipation of turbulent kinetic energy was measured directly. The ratio d* of the shell size and the Kolmogorov length, the size of the smallest eddy in the velocity field, is introduced to quantitatively assess whether turbulence can affect larvae. The laboratory experiments show that mortality increases when d* exceeds 0.9, that is, when the size of the larvae is comparable with or larger than the smallest eddy. The laboratory results are used to show that turbulence can increase veliger mortality in streams and to evaluate the possibility of using bubble screens as a dispersal barrier to control zebra mussels in rivers. If the mortality is due to acute effects of turbulence (taken to be exposure on the order of minutes), the control scheme would work, but if the mortality is due to longer-term exposure, using bubble screens would not be practical.