Oligotrophic vs. Eutrophic Lake

Oligotrophic Lake Eutrophic Lake Deep, steeply banked Large deep—water volume relative to surface—water volume Highly transparent Water blue or green Low nutrient content Oxygen abundant through all levels throughout year Not much phytoplankton; green algae and diatoms dominant Aerobic decomposers favored in profundal zone Low biomass in profundal zone Shallow with broad littoral Small deep—water volume relative to surface—water volume Limited transparency Water green to yellow— or brownish—green High nutrient content Oxygen depleted in deep water during summer Abundant, thick masses of phytoplankton; cyano— bacteria dominant Anaerobic decomposers in profundal zone High biomass in profundal zone