Biodiversity and conservation of Lake Huron's islands

Abstract

Lake Huron has the largest collection of freshwater islands in the world. These islands are a significant contributor to the biodiversity of the region. In this paper, we give preliminary results of a project that assembles mapping of over 23,000 islands and island groups and provides the most comprehensive biodiversity assessment of islands in Lake Huron to date. The number, extent and configuration of many islands, particularly small, low-lying systems, is very dynamic depending on lake-levels. Islands in Lake Huron can be divided into three general groups: 1) limestone and dolostone islands associated with and surrounding Manitoulin and Drummond Islands and the Bruce Peninsula, 2) dense archipelagos of small nearshore Precambrian Shield islands in eastern Georgian Bay and the North Channel and, 3) small groups of low-erodible islands in Saginaw Bay.

All three of these island groups are important for supporting colonial nesting waterbirds, endemic species and communities, and migratory birds. Lake Huron islands have been somewhat buffered from anthropogenic change due to their isolation and therefore support a rich and diverse sets of species and communities. Primary threats to island communities include development and invasive species. Threats are generally greater in many of the southern island regions where fewer islands are protected. Results from this project can be used to set priorities for conservation of key sites with high biodiversity values and conservation urgency.

Keywords:

• Great Lakes
• coast
• nearshore
• Georgian Bay

Acknowledgements

Funding for this project has been provided by the US Environmental Protection Agency – Great Lakes Program Office and the Canada-Ontario Agreement. Information for this paper was created through the Bi-nation Framework for the Conservation of Great Lakes Island project. In addition to the authors, this project team includes: M. Seymour (US Fish and Wildlife Service), R. Greenwood (EPA), K. Vigmostad (IJC), L. Wires (University of Minnesota), F. Cuthbert (University of Minnesota). Team members for the Ontario portion of the project includes: W. Bakowsky (NHIC), B. Crins (Ontario Parks), J. Mackenzie (NHIC) and M. McMurtry (NHIC). GIS and technical support for this project has been provided by G. White (The Nature Conservancy of Canada), J. Slatts (The Nature Conservancy), T. Krahn (Provincial Geomatics Service Centre, OMNR). The authors also wish to thank two anonymous reviewers.

Notes

(1): Some larger islands in Ontario are divided by coastal environments (e.g. Manitoulin Island) and are included in more than one region

(2): Many of the island polygons mapped in the Georgian Bay region may appear as several smaller islands if observed in the field. The configuration and numbers of these islands varies greatly based on water levels.