Biology of the exotic zebra mussel, Dreissena polymorpha, in relation to native bivalves and its potential impact in Lake St. Clair

Abstract

The zebra mussel, Dreissena polymorpha, is a new exotic species that was introduced into the Great Lakes as early as the fall of 1985 . It differs markedly from native species of bivalves in its : (i) shell form ;(ii) mode of life ; (iii) reproductive potential ; (iv) larval life cycle ; (v) population dynamics ; (vi) distribution, (vii) dispersal mechanisms ; (viii) physiology ; (ix) potential impact on the ecosystem ; and (x) impact on society and the economy . In body form, it has an anterior umbone, a flat ventral surface with permanent aperature for the byssal apparatus and a shape that together make the animal well adapted for life on a hard surface . The shell has a zebra-stripe pattern, a heteromyarian muscle condition and lacks hinge teeth which make it easily identifiable from native bivalves . The zebra mussel is strongly byssate and has an epifaunal mode of life not seen in native bivalves . The species is dioecious and has external fertilization, the eggs developing into pelagic veligers which remains planktonic for approximately 4 weeks . Gametogenesis begins in late winter to early spring, veligers appear in the water column in late May to early June and disappear in mid to late October in Lake St . Clair . Adults live for about 2 years and have very rapid growth rates . Maximum shell lengths average 2 .3 to 2 .5 cm . Standing crops as high as 200 000 m-2 are present in the 1-m depths of the Ontario shores . Infestations may be interfering with the normal metabolism of native unionid clams and there is potential of the unionid clam populations being reduced or even eliminated from Lake St . Clair .

Seasonal and Annual Variation in Weight and Biochemical Content of the Zebra Mussel, Dreissena polymorpha, in Lake St. Clair

“…In Lake St. Clair, these temperatures occurred in late May (Table 1). Mackie (1991) May/June time period corresponds to the period of time when large declines in soft tissue weights were found in this study (Fig. 2).…”

Origin of Spanish invasion by the zebra mussel, Dreissena polymorpha (Pallas, 1771) revealed by amplified fragment length polymorphism (AFLP) fingerprinting

“…The epizoic colonisation of snails, crayfish and unionid bivalves by this exotic species has led to a decline, and in many cases to a total eradication, of native species (Mackie 1991;Haag et al 1993;Schloesser et al 1996). Seston removal by filterfeeding of this organism has resulted in the transformation of turbid to clear waters (Reeders et al 1989;Bij de Vaate 1990, 1992;Reeders et al 1993), not only resulting in severe ecological impacts due to complete changeovers of local communities, but also in negative socio-economic impacts on commercial-and sport fisheries due to the decline of commercially important fish species such as the Walleye (Sander vitreus) (Mackie 1991;Griffiths 1993; Van der Velde et al 1994;Strayer et al 1999).…”

Zoochorous dispersal of freshwater bivalves: an overlooked vector in biological invasions?

“…Under optimal conditions, these bivalve species display rapid growth and high levels of fecundity, and can potentially form flourishing populations from a few founder specimens, or in the cases of C. fluminea, from even one self-fertilising individual (McMahon, 2002). In contrast to many freshwater bivalve species, the life cycles of these invaders do not include a parasitic larval stages (Mackie, 1991). Rather, planktonic larval (e.g., veliger) stages can freely swim within the water column until settlement of the post-veliger (e.g., juvenile) stages occurs.…”