MSU Extension

Introduction

Imagine flying over the shoreline of western Lake Erie and seeing a mile-wide swath of grasses and bulrushes rippling in the winds. As the plane passes, thousands of waterfowl rise and take flight to a distant edge of the marsh. We could also be in a canoe, paddling through shallow, meandering channels at the mouth of the River Raisin, gliding through an open bed of wild rice, with broad meadows of blue-joint grass and bulrush surrounding us in all directions. The channel splits again and again before we reach the open waters of the lake.

One hundred and fifty years ago, as the Michigan territory was being settled, broad coastal marshes lined western Lake Erie, Lake St. Clair and the magnificent bird’s-foot delta of the St. Clair River, and many other river mouths and shallow bays of the Great Lakes. Such marshes could be found on all of the Great Lakes, from the western tip of Lake Superior to the upper reaches of the St. Lawrence River and its countless tributaries. Early surveyors and historians described and mapped many of the largest wetlands. These descriptions invariably include uncountable flocks of waterfowl or abundant spawning and feeding fish. For centuries, Native American villages had congregated on the shoreline, attracted by the abundant fish and wildlife. Annual spawning of lake sturgeon, whitefish and suckers and the presence of many other wildlife species provided a bountiful harvest to these original settlers of Michigan.

But as the number of European settlers to the Great Lakes region increased, these protected waters took on other values that conflicted with the ecological values so important to the Native American settlements and the fish and wildlife of the marsh. The river mouths and bays provided refuge to commercial boats and ships. The waters became important for industrial processes such as steam power or cooling. The shorelines were developed as factory or docking sites, requiring the wetlands to be filled. Ship access required dredging, straightening and stabilizing of the lower stream channels. Rapidly the seemingly limitless marshes along the Great Lakes and their connecting channels began to disappear.

In this book, we define and describe the diversity of coastal wetlands found along the Great Lakes shoreline and connecting waterways. Throughout the region, a series of environmental factors converge to create distinctive wetland environments and wetland types with characteristic assemblages of plant and animal species. We identify the natural processes that occur within the various types of coastal wetlands and make Great Lakes wetlands ecologically different from the smaller, inland wetlands familiar to many of us. Finally, we discuss the impacts of human development and land use on coastal wetlands and discuss ways in which we can protect and restore this important natural resource for future generations.

The Natural Setting: The Environmental Context of Coastal Wetlands

Aquatic Environments along the Great Lakes Shoreline

Shoreline Configuration

Wetland Site Types of Lacustrine Systems

Wetland Site Types of Barrier-protected Lacustrine Systems

Wetland Site Types of Riverine Systems

Fluctuations in Great Lakes Water Levels

Wetland Plant Response to Water Level Fluctuations

Bedrock Geology

Climate

Human Land Use and Anthropogenic Stress

The Diversity of Great Lakes Coastal Wetlands

Zonal Wetland Vegetation

Great Lakes Coastal Wetlands of Northern Michigan

Northern Great Lakes Marsh

Plankton: The Hidden World of the Marsh

Northern Rich Fen

St. Marys River Marshes

Macroinvertebrates in Michigan’s Coastal Wetlands

Lake Superior Poor Fen

Fish in Great Lakes Coastal Wetlands

Great Lakes Coastal Wetlands of Southern Michigan

Lake Michigan Drowned River Mouths

Saginaw Bay Lakeplain Marsh

Lakeplain Prairie

St. Clair Lakeplain Marsh

Waterfowl Use of Michigan’s Coastal Wetlands

Lake Erie Lakeplain Marsh

Case History of a Marsh: River Raisin Delta

Restoration and Recovery

Appendices

Appendix A: Marshes in Michigan

Appendix B: Referenced Species

Appendix C: Suggested Readings