Oligotrophic lakes are best characterized by which of the following features?

Oligotrophic lakes are indeed best characterized by low nutrient levels and high oxygen levels. These lakes typically have clear waters, which is a result of low concentrations of algae and aquatic plants. The limited availability of nutrients, such as nitrogen and phosphorus, restricts biological productivity, leading to a lower biomass in comparison to more nutrient-rich, eutrophic lakes.

The high oxygen levels in oligotrophic lakes are primarily due to the abundance of dissolved oxygen, which is often maintained by the colder temperatures of these waters and their greater exposure to the atmosphere. This characteristic is vital for many fish species, especially those requiring well-oxygenated water, such as trout and salmon.

In contrast, lakes with high nutrient levels generally experience eutrophication, leading to increased productivity and the potential for harmful algal blooms, which can deplete oxygen levels and harm aquatic life. Understanding these distinctions helps in assessing the ecological health of aquatic systems and their capacity to support various forms of life.