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U.S. Geological Survey - Great Lakes Science Center

Invasive Dynamics

Invasive species have had a long history in the Great Lakes and are responsible for many negative impacts. Sea lampreys, Phragmites australis, zebra and quagga mussels, Asian carp, round goby, Hemimysis anomala (bloody-red mysid), Bythotrephes longimanus (spiny water flea), and Oriental bittersweet are invasive species for which the USGS-GLSC has focused research projects. Uncovering movement patterns, determining preferred habitats, mapping and modeling locations vulnerable to invasion, estimating population abundances, observing methods of expansion, and documenting relationships and interactions of invasive species with native species are all components of the USGS-GLSC's program. A greater understanding of invasive species ecology allows for better control, improved management, and enhanced protection of Great Lakes ecosystems.


Problem Statement
Lack of a current basin-wide distribution map of established Phragmites stands limited the ability of managers to make decisions on a landscape scale. Similarly, coastal areas most vulnerable to invasion were not identified.


  1. Map current stands of Phragmites in the U.S. coastal zone of the Great Lakes
  2. Model coastal areas most vulnerable to invasion by Phragmites
  3. Publish the data and develop an online decision support tool to allow users to interact with the data

Background & Justification
Alterations to the Great Lakes shoreline or water-level patterns associated with global climate change could have significant impacts on the extent and composition of coastal habitat. Low lake levels can expose fertile wetland bottomlands to invasive species such as common reed (Phragmites). USGS is using remote-sensing data to establish a baseline understanding of current distributions of invasive wetland plants and then forecast potential invasion corridors.

A map of the current Phragmites distribution along the US Great Lakes coastal zone (10-km buffer inland from shore) was generated ( and published as a management decision-support tool ( This map can be used to understand the large-scale factors influencing Phragmites distribution, such as, but not limited to, nutrient loading to the coastal zone, proximity to urban and agricultural land-use types, shoreline development, slope and topography, and water depth. The major influencing factors were used to develop a GIS modeling framework to identify areas vulnerable to invasion by Phragmites.

Principal Investigator: Kurt Kowalski

Problem Statement
Of the many species introduced from other continents or other regions, most are benign, but the few (approximately 5-10%) are highly invasive. Under altered human induced disturbance regimes some native species are also highly invasive and are ecologically and economically problematic. Research is needed on the ecology, impacts and control of such problem invasive species. In this context, studies of comparative or congeneric species can provide significant insights into their ecology and what characteristics make species invasive.


  1. Understand the ecological processes that determine the distribution and abundance of invasive species and identify weak links that might provide some control measures.
  2. Characterize the potential for and the ecological and genetic processes involved in hybridization between congeneric native and invasive species.

Background & Justification
Oriental bittersweet as a liana is of great concern to land managers because it invades many habitats, modifies soil chemistry, alters rates and trajectories of forest succession, girdles trees, and a makes canopy trees susceptible to ice damage and windthrow. It has expanded to cover about three fifths of the lower 48 states of the US and is invading northward into Canada. The science, management, and control of lianas is poorly developed due to their complex growth habit leading researchers and managers to avoid dealing with them. Land managers need science based information about the ecology and control of oriental bittersweet and other woody lianas. This information will be nationally relevant as oriental bittersweet expands westward beyond the eastern Great Plains of North America.

Oriental bittersweet is invading westward through the range of the native American bittersweet. Thus we have a native and invasive congeneric pair of liana species that co-occur in North America. The former species is potentially hybridizing with the native bittersweet and possibly leading to its extinction. The Great Lakes region is suitable for studying this potential hybridization because both species are common in some dune ecosystems and American bittersweet has not declined as much as it has in the Northeast and Atlantic seaboard. In the Great Lakes region, the sand dunes appear to be an important refugia for American bittersweet.

Previous research has examined how best to morphologically distinguish the two species and its distribution and abundance in the forest continuum in the Southern Lake Michigan region.

The objectives of our research program are to provide scientifically based tools for species identification, investigate the potential of hybridization between oriental bittersweet, and understand how wild and prescribed fire influences the regeneration, vegetation reproduction, and spread of oriental bittersweet.

Principal Investigator: Noel B. Pavlovic

Lake-wide adult sea lamprey abundance estimates are a key metric of sea lamprey control program success reported to stakeholders and resource managers. Lake-wide sea lamprey abundance is estimated from a combination of stream-specific mark-recapture estimates, trap catches adjusted for capture efficiency, and model-based estimates based on stream drainage area and treatment history. Lake-wide adult sea lamprey abundance estimates are sensitive to mark-recapture estimates on large rivers, because a small proportion of large rivers are trappable within each Great Lake. Model-based estimates of lake-wide abundance could be improved if abundance of adult sea lampreys could be estimated in large streams that cannot be trapped. Dual-frequency identification sonar (DIDSON) is capable of imaging fish up to 40 m in turbid water and has been used to quantify abundance of salmonids in rivers. We propose to determine if DIDSON can be used to estimate adult sea lamprey abundance in medium and large rivers of the Great Lakes. We hypothesize that the anguilliform swimming pattern of sea lamprey will increase the probability of detecting sea lamprey passage within the DIDSON field of view. We predict that adult sea lamprey abundance estimates based on mark-recapture techniques will not differ significantly from those based on DIDSON. Furthermore, if our hypothesis is supported, DIDSON monitoring will provide previously undocumented insight into the natural timing of the sea lamprey spawning migration. Our objectives are to 1) determine if DIDSON counts of upstream migrating adult sea lampreys differ from mark-recapture estimates of adult sea lamprey abundance in medium and large rivers and 2) determine if timing of the upstream spawning migration of adult sea lampreys differs between trap catches and DIDSON observations.

Principal Investigator: Nicholas Johnson

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