1. Zebra & Quagga Mussel Research
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Environmental Research Laboratory
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Zebra mussels (Dreissena polymorpha) are native to the Quagga mussels (Dreissena rostriformis bugensis) are
Black, Caspian, and Azov Seas. By the early 19th century, native to the Dneiper River drainage of Ukraine. Canals
zebra mussels had spread to almost all major drainages built in Europe allowed range expansion of this species,
of Europe because of widespread construction of canal and it now occurs in almost all Dneiper reservoirs in
systems. They first appeared in Great Britain in 1824 the eastern and southern regions of Ukraine and deltas
where they are now well established. Since then, zebra of the Dnieper River tributaries (Mills et al. 1996). The
mussels have expanded their range into Denmark, quagga mussel was first sighted in the Great Lakes in
Sweden, Finland, Ireland, Italy, and the rest of western September 1989, when one was found near Port Colborne,
Europe. Zebra mussels were first discovered in North Lake Erie. After confirmation that this mussel was not
America in 1988 in the Great Lakes. The first account a variety of Dreissena polymorpha, the new species was
of an established population came from the Canadian named “quagga mussel” after the “quagga”, an extinct
waters of Lake St. Clair, a water body connecting Lake African relative of the zebra. By 2005, quagga mussels
Huron and Lake Erie. By 1990, zebra mussels had been had been found in all the Great Lakes.
found in all the Great Lakes.
PHYSICAL ALTERATIONS DECLINING FISH HEALTH DIPOREIA DECLINES
The hydraulic flow regime of the Detroit While many species of fish will readily Diporeia, a tiny shrimp-like organism,
River has changed since the arrival of eat Diporeia (see right), few species can was the dominant benthic invertebrate
zebra mussels in the late 1980’s. Although use zebra and quagga mussels efficiently in most offshore areas of the Great Lakes
the amount of change is difficult to quan- for food. Moreover, even if a fish since the glaciers receded ~10,000 years
tify, GLERL analyses shows roughness species does eat these mussels, the loss ago. Diporeia have a high lipid (fat)
and slope differences in the lower reach of Diporeia has left many of them with content, with lipids often exceeding 30%
resulting in a change in the hydraulic re- food choices much lower in nutrition of its total weight. As a result, it is rich
gime after 1988. than Diporeia. In Lake Erie, a severe in calories and a good source of energy
decrease in smelt stocks was seen in the for fish. Since the early 1990s population
1990s. Estimates of the slimy sculpin and densities of Diporeia in all the lower Great
lake trout populations in Lake Ontario Lakes have dropped dramatically. “Exact
showed a 95% decline between the late mechanisms are unclear, but the decline
1980s and 1996. In Lake Michigan, many of Diporeia is related to the introduction
fish populations are now sacrificing and expansion of the zebra and quagga
health to feed off zebra mussels. mussels,” says Tom Nalepa, a GLERL
Whitefish, for example, shifted from a biologist who has been sampling Lake
diet of 25-75% Diporeia to a diet of zebra Michigan sediments since the early 1980s.
mussels. During their first 2 weeks of
life, larval bluegill reared in the presence
of mussels grew 24% slower than fish
reared alone. Alewife energy density was
Zebra mussel “reefs” have dramatically 23% lower during 2002-2004 (post zebra
altered the bottom contours of some mussel invasion) compared to 1979-1981
lakes and rivers. (pre zebra mussel invasion). As a result,
a Chinook salmon now needs to eat 22%
more alewives to attain an ideal body Diporeia
weight by age 4.

2. Zebra Mussel Distribution Quagga Mussel Distribution
1994/95 2000 2005 1994/95 2000 2005
101 102 103 104 105 101 102 103 104 105
Density (No. per m2) Density (No. per m2)
NATIVE MUSSELS BENTHIC ALGAE HARMFUL ALGAL BLOOMS
ELIMINATED PROMOTED Nuisance blooms of the toxic blue-green
Zebra mussels altered inner Saginaw alga Microcystis have returned to many
Zebra mussels attach to the shells of na-
Bay from a pelagic-dominated system portions of the Great Lakes since 1992.
tive mussels and alter normal life-sustain-
to a benthic/pelagic system, which will These recent blooms started a few years
ing activities such as feeding, breathing,
have long-term effects on food web after the invasion of zebra mussels and
and eliminating waste products. In addi-
structure and productivity at higher their cousins the quagga mussels in the
tion, large populations of zebra mussels
trophic levels. They are very effective Great Lakes.
substantially reduce the amount of food
available to the native mussels. NOAA’s filter feeders. Because of their population
densities, zebra mussels remove much Using special video equipment,
Great Lakes Environmental Research
of the particulate matter from the water NOAA’s Great Lakes Environmental
Laboratory (GLERL) has monitored
column, leaving the water very clear and Research Laboratory (GLERL) showed
populations of native mussels in Lake St.
allowing increased light penetration. that mussels reject Microcystis but eat
Clair periodically since 1986. Based on
This produced a significant increase in other algae. Thus, the competitors of
surveys between 1986 and 1997, it can
productivity of bottom plants and the Microcystis are removed. At the same
be stated that native mussels have been
amount of bottom area covered with time, the mussels
completely elimi-
plants. are excreting
nated from the
nutrients
open waters
(phosphate
of Lake
and ammonia)
St. Clair.
derived from the
phytoplankton
they eat. These
nutrients, in turn,
serve to fertilize
further growth of
ALTERED CONTAMINANT Microcystis.
CYCLING Algae growth causes muck
Zebra and Quagga mussels have the po- accumulation along the shoreline.
tential to change contaminant cycling in
the Great Lakes by rerouting dissolved For more information:
and particulate-bound contaminants Selected Publications List from
NOAA, Great Lakes
into mussel food chains, with possible 20 Years of GLERL Environmental Research Laboratory
biomagnifications in mussel predators Dreissenid Research 4840 S. State Rd.
and transfer into upper trophic levels. Ann Arbor, MI 48108, 734-741-2235
Selective predation on small, pre-spawn- www.glerl.noaa.gov/pubs/
ing (high lipid) mussels may present a brochures/20dreissenidrefs.pdf www.glerl.noaa.gov
greater hazard than predation on larger
mussels.
May 2008