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There are a number of mechanisms that can cause this switch. To the extent these mechanisms can be minimized or avoided, the clear water condition will be protected: • Destruction of the lake's aquatic plants by: - Mechanical cutting and removal - Boat damage - f-lerbicide use - Extreme water level fluctuations • Interference with buffer mechanisms by: - Excessive pesticide or toxic chemical inputs - Inappropriate changes in fish populations Professor Moss listed these characteristics of the two alternate stable conditions in shallow lakes (Moss 1998): Plant-Dominated • Suppression of eddy currents • Luxury uptake of nutrients • Plant metabolism favorable to fish activity • Provision of structural refuges for zooplankton • Allelopathy • Stabilization of sediment suitable for germination and support of plant propagules Algae-Dominated • Open water habitat allowing for vigorous wind mixing • Early growth of algae that compete with rooted plants for light and carbon dioxide • Structure-less habitat with no refuge for large zooplankton from fish predation • Production of small algae species with high capacity for light absorption • Production of amorphous, watery sediments poorly suited for plant regeneration • Fish communities dominated by planktivorous fish Both conditions are stable. The Challenge The challenge presented by shallow lakes is not so much ecological, but perhaps more sociological. Unlike the United Kingdom and Scandinavia, many shallow lakes in Minnesota - indeed North America as well -are deep lake `wanna-bes.' To paraphrase Garrison Keillor's Prairie Nome Companion mantra, Mmnesota is the dace where all the lakes are c%ar, all the bottoms are sandy and a// the fish are wa//eye. There are many examples of I O-foot-deep lakes trying to live up to this Minnesota ideal. There are an equal number of examples of I O-foot-deep lakes falling short of this ideal and being frustrated.