The genus can be found in oligotrophic, mesotrophic, and eutrophic coastlines. Lakes can be categorized according to the increasing productivity as oligotrophic, mesotrophic, eutrophic, and hypereutrophic. Estuaries tend to be naturally eutrophic because land runoff discharges nutrients into estuaries. Zander inhabit freshwater bodies, preferentially large rivers and eutrophic lakes. In eutrophic lakes, the hypolimnion is often anoxic. They are the most common toxic cyanobacterial bloom in eutrophic fresh water. Unlike most fish species, cyprinids generally increase in abundance in eutrophic lakes. Heavily eutrophic soils are inappropriate for its habitat. The lake is eutrophic or hyper-eutrophic owing to excessive nutrient levels. The periphyton roughly equals the production level in temperate eutrophic lakes. This contrasts sharply with mesotrophic or eutrophic lakes from similar climates. The water must not be nutrient rich (eutrophic). "Spirogyra" is very common in relatively clear eutrophic water, developing slimy filamentous green masses. Due to its shallow depth and warm temperatures, Clear Lake is naturally eutrophic. In some eutrophic aquatic systems, biodilution can occur.