Lake Ecosystem Energetics: The Missing Management Link

ABSTRACT

Phosphorus plays a central role in the bioenergetics of organisms and ecosystems (recall Adenosine Triphosphate [ATP], substrate level phosphorylation, cyclic and noncyclic photophosphorylation). It is a role which no other atom can duplicate. Phosphorus is of paramount importance in lake management because it most often limits the degree of phytoplanktonic autotrophy (algae growth). However, many other aspects of lake ecosystem structure and function offer substantial promise for the future of lake management and restoration. One such aspect, ecosystem energetics, is too often neglected or misunderstood by the lake manager.

There are fundamental differences between autotrophication and allotrophication, trophic and detrital dynamic structures, eutrophication and lake succession, and how these ecosystem components and processes can be effectively managed. An understanding of the nitrogen, sulfur, iron, and phosphorus cycles of lakes yields insight into new restoration technologies (e.g., alum surrogates, anaerobic aeration, biomanipulation) and potential long-term impacts of existing methods (sulfate loading, copper sulfate, aluminum sulfate). Methods to control eutrophication, and its in-lake consequences, are directly related to the energetics of a lake ecosystem, as are treatments of symptoms. Lakes are complex ecosystems in which all living organisms interact collectively with physical and chemical processes of the environment. Understanding a lake ecosystem is understanding nature, and will lead to more effective stewardship of the ecosystem in which we play a major role. This introduction to lake ecosystem energetics is intended to illustrate some fundamental relationships among biology, ecology, physics, chemistry, and lake management.

Key Words:

• ecosystem
• energetics
• respiration
• detritus
• phosphorus
• nitrogen
• autotroph
• heterotroph