Effects of Temperature on Fertilization in Quagga Mussels

Abstract

Quagga mussels, Dreissena bugensis (D. bugensis), are an extremely invasive species that have been infesting US waterways alongside their close relative, zebra mussels. These animals, originating in Europe, have traveled to and across North America through transportation on ships, fishing boats, and in live wells. Their invasion has caused large disturbances in the balance of freshwater ecosystems and ecological deficits due to clogged pipes and damages to the vessels they are transported on. Researchers have estimated that in a 10-year span, $5 billion was spent in an effort to remedy the problems caused by these mussels in the Great Lakes region, alone. Quagga mussels exhibit broadcast spawning, meaning that their fertilization and development occurs outside of the female reproductive tract, making them ideal animals for laboratory study. Once sperm come in contact with the egg in the water column, any number of sperm can bind to the egg; however, not all the sperm enter the egg for fertilization. This initial process occurs over approximately a 15-minute period, following which, the zygote will undergo its first cleavage. This event will occur, typically, within 90 minutes of sperm/egg integration. However, these processes can be slowed down or inhibited due to differences in water temperature. In this study, these effects of water temperature on fertilization and early development are examined in order to more fully understand the temperature range that quagga mussel reproduction requires. This will provide insight into not only laboratory conditions that maximize fertilization success for future studies, but also what latitudes and depths of communities this species can alter through its invasion.