Difference Between Oligotrophic and Eutrophic Lakes

The key difference between oligotrophic and eutrophic lakes is that the oligotrophic lakes contain a very low level of nutrient composition while the eutrophic lakes contain a very high amount of nutrient composition.

There are many lakes located all over the world. They differ by geographic location, pollution rates, environmental conditions and the nutrient contents. Based on the nutrient content, lakes can be classified as oligotrophic lakes, mesotrophic and eutrophic lakes. The trophic states of lakes provide reliable information about the pollution status and the geographical details of the particular area in which the lake situates. When distinguishing between oligotrophic and eutrophic lakes, the main nutrients considered are Nitrogen and Phosphorus.

CONTENTS

1. Overview and Key Difference
2. What are Oligotrophic Lakes
3. What are Eutrophic Lakes
4. Similarities Between Oligotrophic and Eutrophic Lakes
5. Side by Side Comparison – Oligotrophic vs Eutrophic Lakes in Tabular Form
6. Summary

What are Oligotrophic Lakes?

Oligotrophic lakes refer to the lakes that have a very less nutrient composition. Thus, the levels of Nitrogen and Phosphorus in an oligotrophic lake are very low. Highly oxygenated water can be observed in the oligotrophic lakes. Hence the oxygen levels of the water are comparatively high. The water in oligotrophic lakes is also very cold. This increases the dissolution of oxygen in the water, further increasing the oxygen levels. The bottom water of the oligotrophic lake makes it difficult for the survival of most aquatic organisms due to very low temperature. The fish found in oligotrophic lakes include whitefish and trout.

The algal content in oligotrophic lakes is very low as they do not have adequate nutrient conditions. Therefore, light penetration is high, and there is no odor emitting from oligotrophic lakes.

The decomposition process in oligotrophic lakes is very slow as there are very fewer decomposers due to the less availability of nutrients. Presence of oligotrophic lakes also suggests that the pollution level and surface runoff containing chemicals is less in that area.

What are Eutrophic Lakes?

Eutrophic lakes are the lakes that have an excessive algal growth due to the high content of nutrients. Eutrophication is the process that creates this kind on lakes. In eutrophic lakes, there is a high content of Nitrogen and Phosphorus. Since eutrophic lakes are rich in nutrients; they support for the increased growth of algal forms such as Chlorella and Spirulina.

This increases the biological oxygen demand. Thus, the bottom of the lake is most often anoxic as it doesn’t receive ample amount of oxygen. Due to the growth of excel algal blooms, the penetration of light into the lake also decreases. Decomposition rate is high in eutrophic lakes hence, there is an odor coming out from these lakes.

What is the Similarity Between Oligotrophic and Eutrophic Lakes?

• Both types of lakes depict the nutrient levels of the aquatic environments.

What is the Difference Between Oligotrophic and Eutrophic Lakes?

Oligotrophic and eutrophic lakes are two types of lakes defined based on the nutrient composition of the lake. Oligotrophic lakes do not contain a high level of nutrients. Hence, they contain oxygen-rich clean water. On the other hand, eutrophic lakes contain high levels of nutrients mainly nitrogen and phosphorus hence, they have increased growth of algal blooms. This is the key difference between oligotrophic and eutrophic lakes. Furthermore, another notable difference between oligotrophic and eutrophic lakes is that the eutrophic lakes have a high oxygen demand and high rate of decomposition.

The below infographic presents an in-depth analysis of the difference between oligotrophic and eutrophic lakes.

Summary – Oligotrophic vs Eutrophic Lakes

Trophic level of the lakes defines based on the nutrient composition of the lake. There is a minute concentration of nutrients present in the oligotrophic lakes. In contrast, there is a high concentration of nutrients in the eutrophic lakes. Furthermore, in eutrophic lakes, there is a high level of nitrogen and phosphorus. Eutrophic lakes result due to excess surface run-off water from agricultural lands and due to pollution. Therefore, eutrophic lakes are rich in algal populations and lead to fast decomposition of dead aquatic organic matter. In comparison, oligotrophic lakes have a very less or absence of algal forms and contain clear cold water. This is the difference between oligotrophic and eutrophic lakes.

Reference:

1.“Lake Trophic States.” RMBEL. Available here 
2.Martin, Pierre, and Robert A. MacLeod. “Observations on the Distinction Between Oligotrophic and Eutrophic Marine Bacteria.” Advances in Pediatrics., U.S. National Library of Medicine, May 1984. Available here 

Image Courtesy:

1.”Lake George from village beach”By Daniel Case – Own work, (CC BY-SA 3.0) via Commons Wikimedia
2.”River algae Sichuan”By Felix Andrews (Floybix) – Own work, (CC BY-SA 3.0) via Commons Wikimedia