Title

Mapping cladophora and other submerged aquatic vegetation in the Great Lakes using satellite imagery

Document Type

Conference Paper/Presentation

Publication Date

2013

Abstract

The Michigan Tech team has developed and verified a remote sensing algorithm to map the extent of Cladophora and other submerged aquatic vegetation (SAV) in coastal waters using a depth-invariant bottom reflectance index. With this algorithm, maps of SAV were generated from recent Landsat satellite imagery for all optically visible areas of the lower four Great Lakes. The area mapped varies depending on water clarity, with maximum mapping depth ranging from >20 m in Lake Michigan to 7 m in Lake Erie. The maps show that 28%, 15%, 30%, and 40% of the visible bottom of Lakes Michigan, Huron, Erie and Ontario, respectively, are colonized by SAV. The total mapped area of SAV is estimated to represent between 130,000 and 260,000 metric tonnes dry weight based on published biomass density measurements. This new mapping approach was validated using field data for an overall map accuracy of 83%. The archive of Landsat imagery dating back to 1973 was also utilized to document historic changes in SAV extent and water clarity, showing increases in SAV extent in most areas following the introduction of invasive mussels. A seasonal analysis of SAV extent revealed intra-annual changes of ~5% or less. The time series analyses also captured the observed increases in water clarity in all four lakes.

Publisher's Statement

© 2013 The authors.

Publication Title

IAGLR 56th Annual Conference on Great Lakes Research