Great Lakes Cladophora Mapping

Cladophora, a nuisance, native green algae that grows attached to solid substrate in all of the Laurentian Great Lakes, has expanded its range partially due to invasive quagga and zebra mussels. During significant storm events it detaches and washes up on lakeshore beaches, causing outbreaks of avian botulism as it decays. Our research question has been, "Can Cladophora extent be mapped using satellites for mitigation of this problem?"

A depth-invariant algorithm developed at MTRI has been used successfully with satellite imagery to map Cladophora on the bottom of Lake Michigan under NASA funding. Under a GLRI grant, we are mapping the near-shore extent of Cladophora for Lakes Michigan, Huron, Erie and Ontario (Cladophora is not yet a significant issue in colder Lake Superior).

Satellite-Derived Lake Michigan Submerged Aquatic Vegetation (SAV) Map

Link to the 11x17 inch map (adobe .pdf) >>>

MTRI generated the Satellite-Derived Lake Michigan SAV Map (above) under the Great Lakes Restoration Initiative (GLRI) funding (award no. GL-00E00561-0), which represents the extent of SAV in the optically shallow areas of Lake Michigan (areas where there is a return of light from the bottom). The SAV is predominantly Cladophora, with localized areas of macrophytes, Chara, and diatoms. The map, which has a 30 meter resolution, was generated using a MTRI-developed depth-invariant algorithm, and utilized Landsat satellite data from 2008-2011 collected during the vegetative growing season (April-May). The total area of optically shallow water mapped is approximately 4,210 square kilometers of which 1,024 square kilometers or 24% is mapped as SAV. The wet weight biomass of the SAV is estimated at a conservative weight of 375,000 metric tonnes, using an area-weighted average dry weight of 36 g/meter2.

The Cladophora map (below) was created using band 1 and band 2 depth invariant index with May 16, 2010 Landsat 5 satellite imagery. Landsat is the best compromise between cost and resolution for this analysis.

Cladophora extent has been successfully mapped in the nearshore using Landsat 5 and 7 imagery in addition to commercial satellite imagery. Moreover, Landsat satellites offer a near-nadir, consistent viewing geometry that is helpful for Cladophora mapping. The historical archive offered by Landsat is longer than any commercial satellites, allowing for long-term time series analysis of Cladophora growth. Continued support from existing and future Landsat missions is essential for this and other Great Lakes research programs.

For Additional Information

Robert Shuchman, Ph.D.
Co-Director
734.913.6860
shuchman@mtu.edu

Michael Sayers
Research Engineer
734.913.6852
mjsayers@mtu.edu

Colin Brooks
Research Scientist, Manager of the Environmental Sciences Lab
734.913.6858
colin.brooks@mtu.edu

Martin Auer, Ph.D.
Professor - Michigan Technological University
906.487.2799
mtauer@mtu.edu

(Above) Cladophora washed up the shore of North Manitou Island, June 2010.

Research is funded by EPA's Great Lakes Restoration Initiative (GLRI) and NASA. Research contributors are scientists and engineers at Michigan Technological University and the University of Michigan.

Project results will be made available on the MichiganView (www.michiganview.org) and GLOS (http://glos.us) websites as they are finalized.

Watch researchers on YouTube explain the Cladophora research being done at MTRI.