Comparison of benthos and plankton for selected areas of concern and non-areas of concern in western Lake Michigan Rivers and Harbors in 2012

Scientific Investigations Report 2016-5090
Prepared in cooperation with the Wisconsin Department of Natural Resources and the U.S. Environmental Protection Agency—Great Lakes National Program Office
By: , and 

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Abstract

Recent data are lacking to assess whether impairments still exist at four of Wisconsin’s largest Lake Michigan harbors that were designated as Areas of Concern (AOCs) in the late 1980s due to sediment contamination and multiple Beneficial Use Impairments (BUIs), such as those affecting benthos (macroinvertebrates) and plankton (zooplankton and phytoplankton) communities. During three seasonal sampling events (“seasons”) in May through August 2012, the U.S. Geological Survey collected sediment benthos and water plankton at the four AOCs as well as six less-degraded non-AOCs along the western Lake Michigan shoreline to assess whether AOC communities were degraded in comparison to non-AOC communities. The four AOCs are the Lower Menominee River, the Lower Green Bay and Fox River, the Sheboygan River, and the Milwaukee Estuary. Due to their size and complexity, multiple locations or “subsites” were sampled within the Lower Green Bay and Fox River AOC (Lower Green Bay, the Fox River near Allouez, and the Fox River near De Pere) and within the Milwaukee Estuary AOC (the Milwaukee River, the Menomonee River, and the Milwaukee Harbor) and single locations were sampled at the other AOCs and non-AOCs. The six non-AOCs are the Escanaba River in Michigan, and the Oconto River, Ahnapee River, Kewaunee River, Manitowoc River, and Root River in Wisconsin. Benthos samples were collected by using Hester-Dendy artificial substrates deployed for 30 days and by using a dredge sampler; zooplankton were collected by net and phytoplankton by whole-water sampler. Except for the Lower Green Bay and Milwaukee Harbor locations, communities at each AOC were compared to all non-AOCs as a group and to paired non-AOCs using taxa relative abundances and metrics, including richness, diversity, and an Index of Biotic Integrity (IBI, for Hester-Dendy samples only). Benthos samples collected during one or more seasons were rated as degraded for at least one metric at all AOCs. In the Milwaukee Estuary, benthos richness was lower in the Milwaukee River subsite spring and summer samples and in the Menomonee River subsite spring sample relative to the paired non-AOCs. Benthos diversity and IBIs at the Menomonee River subsite and IBIs at the Milwaukee River subsite and Sheboygan River were significantly lower than at all non-AOCs as a group across all seasons and therefore were rated as degraded. In addition, IBIs at the Lower Menominee River were significantly lower than those at the paired non-AOCs during all seasons and were therefore rated degraded. Benthos at both Fox River subsites and the Milwaukee River subsite were significantly different from their paired non-AOCs during all three seasons, based on a comparison of the relative abundances of taxa using multivariate testing. Metrics for plankton at AOCs were not significantly lower than those at the paired or group non-AOCs during all seasons; however, zooplankton richness in spring at the Sheboygan River and in fall at the Menomonee River subsite was rated as degraded in comparison to paired non-AOCs. Also, zooplankton richness in fall at the Fox River near Allouez subsite and in spring at the Milwaukee River subsite was rated degraded overall because values were lower than at all non-AOCs as a group and lower than at the paired non-AOCs. Zooplankton diversity in fall at the Fox River near Allouez subsite and the Lower Menominee River was rated degraded in comparison to paired non-AOC comparison sites. Zooplankton communities at the Fox River near Allouez subsite were significantly different from the paired non-AOCs when multivariate comparisons were made without rotifers other than A. priodonta. Overall, benthos and zooplankton BUIs remained at the AOCs in 2012 but no AOCs with a phytoplankton BUI were rated degraded in comparison to non-AOCs. The use of a multiple ecological measures, structural and functional, and multiple statistical analyses, biological metrics and multivariate statistics, provided assessments that defined 2012 status of communities relative to less-impaired non-AOCs in the Great Lakes area.

Suggested Citation

Scudder Eikenberry, B.C., Bell, A.H., Templar, H.A., and Burns, D.J., 2016, Comparison of benthos and plankton for selected Areas of Concern and non-Areas of Concern in Western Lake Michigan Rivers and Harbors in 2012: U.S. Geological Survey Scientific Investigations Report 2016–5090, 28 p., http://dx.doi.org/10.3133/sir20165090.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Methods
  • Condition of the Benthos and Plankton Communities
  • Summary and Conclusions
  • References 

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Comparison of benthos and plankton for selected areas of concern and non-areas of concern in western Lake Michigan Rivers and Harbors in 2012
Series title Scientific Investigations Report
Series number 2016-5090
DOI 10.3133/sir20165090
Year Published 2016
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Wisconsin Water Science Center
Description vi, 38 p.
First page 1
Last page 28
Country United States
State Michigan
Other Geospatial Lake Michigan
Online Only (Y/N) Y
Additional Online Files (Y/N) N