Title

Using a satellite time-series dataset to analyze growth of cladophora and other submerged aquatic vegetation in the Great Lakes

Document Type

Conference Paper/Presentation

Publication Date

2014

Abstract

Using Landsat imagery back to 1973, we have documented historic changes in the extent and distribution of submerged aquatic vegetation (SAV) in the lower four Great Lakes, showing decreases in SAV extent in most areas following the introduction of phosphorus targets to the Great Lakes Water Quality Agreement, with resurgence of SAV in the wake of the introduction of invasive mussels. We also captured the observed increases in water clarity in all four lakes over time. An MTRI algorithm helped produce maps of SAV in the nearshore zone of inland waters via an index that corrects for the effect of water depth for the lower four Great Lakes that are shallow enough to detect the lake bottom. Maximum mapping depth ranged from >20 m in Lake Michigan to 7 m in Lake Erie. This mapping approach has been validated for an overall map accuracy of 83%. Overall, the time series analysis indicates that the effects of invasive mussels on water clarity and phosphorus availability in the Lakes are enabling an increase in benthic SAV biomass, in deeper water than was previously possible, resulting in nuisance blooms of benthic vegetation even in areas without obvious local point sources of nutrients. These new maps will support Cladophora management efforts and help to prioritize areas for nutrient abatement programs.

Publisher's Statement

© 2014 The authors.

Publication Title

IAGLR 57th Annual Conference on Great Lakes Research