How do Dreissena spp. reproduce?
Both the quagga mussel and zebra mussel are prolific breeders possibly contributing to their spread and abundance. Dreissena are dioecious (either male or female) with external fertilization. A fully mature female mussel is capable of producing up to one million eggs per season. After fertilization, pelagic microscopic larvae, or veligers, develop within a few days and these veligers soon acquire minute bivalve shells. Free-swimming veligers drift with the currents for three to four weeks feeding by their hair-like cilia while trying to locate suitable substrata to settle and secure byssal threads. Mortality in this transitional stage from planktonic veliger to settled juveniles may exceed 99% (Bially and MacIsaac, 2000).
