24fi 



Aciuatic Ecosyslfins — Our Living Resources 



wetland vegetation. Dominants included grass- 

 es, sedges, rushes, short emergent plants, and 

 submersed aquatic vegetation. At elevations that 

 were rarely or never dewatered, submersed and 

 floating plants were dominant, with emergent 

 plants also occun'ing at some sites. 



Lake Superior 



Water levels on Lake Superior have been 

 regulated for much of this century, although the 

 range of tluctuations and the cyclic nature of 

 high and low lake levels have not been altered 



183.5 



1830 



182.5 



182 



75.0 



.9 74.0 



73.0 



Figure. Schematic cross-sections depicting tlie structural habitat provided by plant communities characteristic of regulated Lakes Superior and Ontario. 

 Elevations at which vegetation sampling was conducted are shown beneath each cross-section (benchmark: International Great Lakes Datum 1955). 



