Lake and Pond Ecology

Oligotrophic (pristine) phase

Oligotrophic lakes are those that are generally clear, deep, have low primary prduction and are clear and pristine. The food chain in oligotrophic lakes is very structured and is capable of sustaining a fishery of large game fish. These lakes tend to be the most aesthetically pleasing due to their clear blue water. Usually they have a very high clarity reading and low phosporus and chlorophyll readings.

Mesotrophic phase (most lakes)

Mesoytrophic lakes are in the boundary between oligotrophic lakes and eutrophic lakes. They have more nutrients and production than the oligotrophic lakes, but not nearly as much as eutrophic lakes. Mesotrophic lakes have some accumulated organic matter on the bottom, as well as an occasional algae bloom at the surface. They are usually good lakes for fishing, as they are able to support a wide variety of fish. Mesotrophic lakes have water clarity, phosphorus and chlorophyll readings between those of eutrophic and oligotrophic lakes.

Eutrophic phase (problem lakes)

Eutrophic lakes support a very large biomass and are thus normally weedy and subject to frequent algae blooms. There is often a large amount of accumulated organic matter on the bottom of the lake.
Eutrophic lakes are susceptible to oxygen depletion and have low water clarity readings in relation to their depth, high phosphorus and high chlorofyll readings. Most problems occur in Eutrophic lakes.
Nearly all urban lakes and ponds are now Eutrophic in nature.