What term describes a young lake?

The term that describes a young lake is "oligotrophic." Oligotrophic lakes are characterized by their clear waters, low nutrient content, and minimal organic matter. These lakes typically have a high oxygen level and support a diverse range of aquatic life, particularly fish species that thrive in cooler, well-oxygenated waters.

Oligotrophic lakes are often formed in glacial regions and have undergone minimal biological and chemical changes since their formation. This youthful condition contributes to their clarity and low productivity, as they have not yet accumulated significant amounts of nutrients that would foster higher plant and algae growth.

In contrast, the other terms describe different stages of lake development. Eutrophic lakes are older and nutrient-rich, leading to higher productivity and often problematic algal blooms. Mesotrophic lakes represent a middle stage, having moderate nutrient levels. Heliothermic pertains to temperature changes related to sunlight exposure, rather than the development stage of a lake. Thus, the identification of oligotrophic as the correct term aligns with the characteristics of a young lake.