An oligotrophic lake is characterized by which?

• A. Shallow lake with many nutrients
• B. Deep lake with few nutrients and little organic material
• C. Wetlands with vegetation
• D. Sea water with minerals

Answer: (B)

Oligotrophic lakes have very low nutrient levels, which keeps primary production low and the water clear. They are typically deeper relative to their size, with little organic material accumulated in the water or sediment. This combination of low nutrients and depth produces the characteristic clarity and low productivity.

The description that fits this best is a deep lake with few nutrients and little organic material, because it reflects both the scarcity of nutrients that limits algae and the depth that helps keep the water clear. In contrast, a shallow lake rich in nutrients tends to be murkier and more productive (eutrophic); wetlands with vegetation and seawater are different kinds of environments and don’t match the freshwater oligotrophic lake profile.