STATE OF THE GREAT LAKES
WHAT IS THE STATE OF GREAT LAKES COASTAL WETLANDS?
Great Lakes coastal wetlands are in peril as indicated by the decrease of coastal wetland area, declining wetland-
dependent bird and amphibian populations, and deteriorating plant community health.
The Issues
• An estimated 50 percent of Great Lakes
wetlands have been lost basinwide, with losses
of up to 90 percent occurring in some areas.
Currently, 216,743 hectares of coastal wetlands
have been identified along the Great Lakes and
connecting rivers up to Cornwall, Ontario.
However, the inventory is incomplete and
underestimates the total wetland area
remaining, especially for the upper Great Lakes.
• Great Lakes coastal wetlands are degrading
because of impacts from water level
stabilization, sedimentation, contaminant and
nutrient inputs, climate change, non-native
species invasions, and intensive industrial,
agricultural and residential development.
The Indicators
Thirteen indicators have been recommended to
assess the status of Great Lakes coastal wetlands.
These indicators evaluate coastal wetland plant and
animal (invertebrate, fish, amphibian, bird,
snapping turtle) community health, the effects of
water level fluctuations on wetland habitats, and
the quantity and quality of remaining coastal
wetland area.
The Assessment
Despite significant historical loss of coastal wetland
habitat in some regions of the Great Lakes, the
Great Lakes and connecting rivers still support
diverse wetlands. Barrier protected coastal
wetlands (wetlands that are physically separated
from the Great Lakes by barrier beaches or a series
of beach ridges) account for over 60,000 hectares of
identified coastal wetland area in Lakes Superior,
Huron and Michigan. One-third of Lake Erie's
22,057 ha of coastal wetlands are protected
embayment wetlands (wetlands protected from
wave action by a partial barrier beach or dike across
the wetland mouth). In Lake Ontario, barrier
protected and drowned river mouth coastal wetlands
(wetlands formed where streams slow as they enter
the lake and deposit fine sediments) account for
19,172 hectares, approximately three-quarters of the
total coastal wetland area. The St. Clair River delta is
the largest single wetland feature in the Great Lakes,
occupying over 13,000 hectares. The upper St.
Lawrence River, near Lake Ontario, supports a large
area of wetland habitats, typically numerous small
embayment and drowned river mouth wetlands
associated with the Thousand Islands region.
Coastal wetland plant community health varies
across the Great Lakes region. Long-term water level
fluctuation, vital to maintaining wetland plant
diversity, naturally stresses coastal wetlands. In some
wetlands, plant communities are deteriorating due to
extremely low water levels. One consequence of
reduced water level fluctuation due to water level
stabilization in Lake Ontario is that coastal wetlands
are comprised of fewer plant species. Recent low
water levels on the other Great Lakes have facilitated
the germination and expansion of diverse plant
communities in many coastal wetlands, especially in
Lake St. Clair and southern Lake Huron. Low water
levels and shoreline alterations facilitate non-native
plant species invasions that further degrade coastal
wetland plant communities.
Southern Michigan coastal wetland. Photo: Dennis Albert.
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WHAT IS THE STATE OF GREAT LAKES
COASTAL WETLANDS?
Fish community composition is often related to
plant community type and quality. Coastal
wetlands in northern Lake Michigan, northern
Lake Huron, and Lake Superior have relatively
diverse fish communities. Lakes Erie and Ontario
have more wetlands containing cattails, which are
indicative of nutrient enrichment, and fish
communities in these wetlands tend to be less
diverse than fish communities in other plant
community types. Wetlands may be a refuge for
native fishes from the influence of certain invasive
fish species, such as the round goby and ruffe.
From 1995 - 2002, 53 bird species that feed and/or
nest in marshes were recorded by volunteers
throughout the Great Lakes region. Population
index declines were observed for the least bittern,
black tern, marsh wren, undifferentiated American
coot/common moorhen, pied-billed grebe, red-
winged blackbird, and Virginia rail. Population
index increases were observed for the willow
flycatcher, common yellowthroat, and mallard. In
the coastal wetlands of Lakes Erie, Michigan, and
Huron, population index trends of the American
coot, least bittern, marsh wren, pied-billed grebe,
sora, swamp sparrow, and Virginia rail tracked
fluctuations in Great Lakes water levels.
Snapping turtles are predators at the top of the
coastal wetland aquatic food web, and through
their diet they accumulate persistent toxic
contaminants that have become concentrated in
their prey. Although contaminant concentrations
are declining in snapping turtle eggs, levels of
many contaminants in fish still exceed the 1998
Canadian Council of Ministers of the Environment
and 2001 Ontario Ministry of the Environment
sport fish consumption guidelines. This indicates
that contamination is present throughout the
coastal wetland aquatic food web.
Basin-wide surveys have detected declines in the
occurrence of American toad, chorus frog, green
frog, and northern leopard frog throughout
wetlands in the Great Lakes region.
Current Actions
The Great Lakes Coastal Wetlands Consortium was
formed in 2000 to develop coastal wetland indicators
and establish a long-term coastal wetland monitoring
program. This Consortium, funded through a
cooperative agreement between the Great Lakes
Commission and the U.S. EPA Great Lakes National
Program Office, in partnership with a binational
group of agencies and organizations, serves as
decision support for programs and policies affecting
the conservation and management of Great Lakes
coastal wetlands.
Actions Needed
Loss of wetland habitats and adjacent upland areas
must be prevented. There is also a need to address
impacts that degrade wetland health such as water
level stabilization, contaminant and nutrient inputs,
sedimentation, and invasion of wetlands by non-
native plants and animals. Future water withdrawals
and diversions from the Great Lakes are potential
pressures on wetlands. Climate change also has the
potential to alter water levels in wetlands.
To Learn More
For further information related to Great Lakes coastal
wetlands, refer to the State of the Great Lakes 2005
report which, along with other Great Lakes
references, can be accessed at
www.epa.gov/glnpo/solec. For more information
about the Great Lakes Coastal Wetlands Consortium,
visit www.glc.org/wetlands.
Duck Bay, Lake Huron. Photo: Ted Cline.
02/06
EPA905-F-06-900
IISG-05-26
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