Effects of x-ray irradiation on fertilization and early development in quagga mussels (Dreissena bugensis)

The quagga mussel, Dreissena bugensis, is an invasive freshwater bivalve that causes significant economic and ecological damage. Numerous techniques are currently being investigated to help control their spread. X-ray irradiation has been used in different techniques to help control the spread of invasive species, either through decontamination or by the production of sterile male that reduce reproductive populations (Sterile Male Release Technique). Most studies have focused on terrestrial species, fewer looking at the effects of irradiation on aquatic species. This study was designed to evaluate the effects of x-ray irradiation on quagga mussels both in its effectiveness to kill mussels or to produce sterile males. Adult mussels were irradiated with a range of exposures from 0 (control), 6, 30, to 50 Gy to determine the effect on quagga mussel survival and impact on reproduction. The results demonstrated that x-ray treated quagga mussels had lower developmental success than the control. Adult quagga mussels were highly tolerant of x-ray irradiation with high survival rates (> 95%) after treatment. Mussels from all treatments produced motile sperm and these sperm were able to bind and fuse with eggs. There was a decrease in sperm binding between treatments, but fertilization still occurred. Fertilized eggs in all treatments were able to divide and produce swimming trochophores, but irradiation appears to decrease development between zygote and trochophore stage. The current experiment was not able to produce completely sterile males, even at the highest irradiation of 50 Gy in a single 8-minute session. The current experiment did not find an x-ray dose leading to the generation of 100% sterile males. Even at higher doses, x-ray irradiation may not be realistic for implementation.