What defines oligotrophic water bodies?

Oligotrophic water bodies are characterized by low nutrient levels, particularly nitrogen and phosphorus, which results in typically pristine water conditions. These environments tend to support lower primary productivity, meaning that there's a limited amount of plant growth, including algae.

Because oligotrophic waters have low nutrient availability, they often exhibit high oxygen concentrations, especially in deeper layers where photosynthesis is minimal but oxygen can still be replenished through atmospheric diffusion and water mixing. The clarity of oligotrophic waters allows sunlight to penetrate deeper, further contributing to the oxygen levels as aquatic plants perform photosynthesis.

In contrast, higher nutrient levels can lead to eutrophication, a process that results in increased algal blooms and decreased oxygen levels due to decomposition, which fundamentally differs from the environments described as oligotrophic. Thus, the defining attributes of oligotrophic water bodies align closely with low nutrient levels and high oxygen concentration.