Dystrophic

A dystrophic lake refers to a lake containing brown- or tea-coloured water which is the result of high concentrations of humic substances and organic acids suspended in the water. In response to historical misuse of the term in literature, these lakes are better referred to as "humic lakes". Although dystrophic lakes are often considered acidic and nutrient-poor (oligotrophic), these lakes actually vary greatly in terms of both pH and productivity. Due to the low pH associated with dystrophic lakes, few bacterial species and other aquatic life are able to survive. They are common in the taiga of North America and Eurasia.

An example of this type of lake is Humic Lake in South Georgia, named for the dark water caused by the leaching of decaying peat from nearby slopes. In the dystrophic Lake Flosek in Poland, the abundance peaks of autotrophic picoplankton and phytoplankton varied from non-dystropic lakes. In the dystrophic lake Flosek, there were two abundance peaks of autotrophic picoplankton and phytoplankton, while non-dystrophic lakes had one abundance peak.

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