Dreissenid Life History

 

Zebra and quagga mussels are closely related filter-feeding freshwater mussels (Table 1), capable of filtering about one liter of water per day while feeding on algae (Benson et al. 2017). These bivalves produce free-swimming planktonic larvae that eventually settle out of the water column and attach to hard surfaces using byssal threads. Zebra mussels tend to prefer hard surfaces, whereas quagga mussels can inhabit both hard and soft substrates up to depths of 130 meters (USGS 2016). Although quagga mussels can colonize more surfaces in a lake, zebra mussels are more likely to successfully invade river systems (but will not settle in currents greater than 2m/sec) because zebra mussels have stronger byssal threads and a distinctive flat edge that may increase their stability and grip on hard surfaces (Oregon Sea Grant 2010).

 

Dreissenids are highly invasive because they are dioecious (fertilization occurs in the water column), and they have a high reproductive capacity (they can produce millions of eggs in one spawning season) (Oregon Sea Grant 2010). Males and females release their eggs and sperm simultaneously into the water, where they are fertilized and develop into microscopic planktonic larvae, called veligers. The veligers settle, attach to a substrate using byssal threads, and develop into adult mussels in the first or second year of life. The threads can be broken, enabling the mussels to translocate to new areas (Ackerman et al. 1994).

 

Zebra mussels can survive in waters as warm as 86°F. Both species can survive cold waters near freezing, but cannot tolerate freezing. Zebra mussels need waters above 54°F to reproduce whereas quagga mussels need waters above 48°F to reproduce. The temperature preference for zebra and quagga mussels is 64°F and 61°F, respectively (US Fish and Wildlife Service 2007). Neither species can survive salinity tolerances greater than 5 parts per thousand (Spidle et al. 1995).

 

Bacteria are the main food for the larval stage of dreissenids. Adult quagga and zebra mussels filter feed on phytoplankton and zooplankton from the water column; one mussel can filter one liter of water per day (Oregon Sea Grant 2010).

 

Table 1. Zebra and quagga mussel comparison chart. Source: Oregon Sea Grant (2010).

TRAIT

ZEBRA MUSSELS

QUAGGA MUSSELS

Shell

Triangular shape, underside flat. Obvious ridge between side and bottom. When placed on its ventral side, it will remain upright.

Rounder sides, convex underside. No ridge. When placed on its underside, the quagga mussel will topple.

Color

Variable colors and patterns, usually dark

Pale near hinge, dark concentric rings on the shell

Underside

Large groove in middle of flat side; allows tight hold on rocks

Small ventral groove near the hinge

Depth in lake

3 to 98 feet; rarely found below 50 feet

3 to 540 feet; expected to go deeper over time

Temperature tolerance

54°F to 68°F

39°F to 68°F

Spawning temperature

Minimum 56°F; can survive in stagnant water with uniform temperature, but cannot reproduce there

Minimum 50°F; a female quagga mussel with mature reproductive organs was found in Lake Erie at a temperature of 42°F

Habitat occupied

Lakes, waterways, and ponds, and rivers with current less than 2m/sec

Lakes, waterways, and ponds

Substrate colonized

Hard only

Hard and soft