Eutrophic lake

A eutrophic lake (Eu meaning good/well and trophic meaning food/nutrients) is a lake with high primary productivity, the result of high nutrient content. These lakes are subject to excessive algal blooms, resulting in poor water quality. The bottom waters of such lakes are commonly deficient in oxygen, ranging from hypoxic to anoxic; thus, such lakes commonly lack those fish species, like trout, which require cold, well-oxygenated waters. This oxygen deficiency is most apparent in shallow lakes, owing to the smaller hypolimnetic volume. Ecologists use the term to distinguish productive lakes with an ample or excessive nutrient supply from unproductive oligotrophic ones, characterized by a nutrient deficiency. Mesotrophic lakes are lakes with an intermediate level of productivity, greater than oligotrophic lakes, but less than eutrophic lakes. The process of eutrophication may occur naturally or be the result anthropogenic influences.