lake stratification and dissolved oxygen
Figure 7. JSTOR®, the JSTOR logo, JPASS®, Artstor®, Reveal Digital™ and ITHAKA® are registered trademarks of ITHAKA. Dissolved Oxygen Just after summer stratification is established, the hypolimnion is rich in dissolved oxygen from the early spring mixing of the lake. The lake was relatively uniform in the horizontal direction and significantly stratified vertically. One of the most user-friendly data portals is the Great Lakes FieldScope project. Authors: Lindstedt, D.Website, accessed December 1, 2009. Describe what thermal stratification is and why some lakes in temperate regions stratify. This promotes atmospheric diffusion of oxygen into the water. How can dissolved oxygen levels influence organisms living in a lake? Identified tropic levels are: In eutrophic lakes, such as Lake Erie, large blooms of algae grow at the surface during the summer. A discussion of a few stratification impacts follows. For terms and use, please refer to our Terms and Conditions With a growing open access offering, Wiley is committed to the widest possible dissemination of and access to the content we publish and supports all sustainable models of access. Michigan Department of Environmental Quality (MDEQ). Introduce the concept of dead zones. Construct and interpret graphs of dissolved oxygen and water depth. The permanent stratification has decisive impact on the redistribution of dissolved substances, such as nutrients or oxygen, and hence determines the biocenosis that can form in the lake [e.g., Gaedke et al., 1998; George and Hewitt, 2006; Thackeray et al., 2006]. Michigan Sea Grant helps to foster economic growth and protect Michigan’s coastal, Great Lakes resources through education, research and outreach. All Rights Reserved. This lesson and activity utilize the 5 E learning cycle. Encourage students to ask questions about. The reason is again the stratification of the lake. The dissolved oxygen probe is relatively accurate at high and medium oxygen concentrations, but takes increasingly longer times to equilibrate at very low oxygen concentrations, and may indicate slight amounts of oxygen present when there is actually no oxygen. (e.g., Lake Erie). Upon completion of this lesson, students will be able to: From late spring through early fall, some lakes in temperate climates experience thermal stratification, a phenomenon wherein lakes separate into three distinct thermal layers (Figure 1). Density differences in water bodies facilitate an evolution of chemical differences with many consequences for living organisms in lakes. How can human activities affect dead zones? The stratification periods expand up to 23% (46 days), thermocline depths increase 49%, and the onset of anoxia occurs 4 weeks earlier under the future climate scenarios. Read your article online and download the PDF from your email or your account. Lake stratification is the separation of lakes into three layers The 3 Layers of freshwater are: ... slowly loses its dissolved oxygen and become less able to support aquatic life. Especially, lakes in volcanic areas are known for the continuous recharge of dissolved substances (e.g., Lake Nyos and Lake Kivu in East Africa, Lake Monoun see Figure 8). Evaluation is ongoing. In this section students are provided with additional resources on hypoxia. Moderate and heavy rainfall events could reduce the thermal stability of water column, deepen the mixing layer depth, and shape the thermocline, resulting … Diel dissolved oxygen variations were less than 0.5 mg/l in surface regions. Figure 2. Guide to Writing An Inquiry-based Question, Next Generation Science Standards Summary, How dissolved oxygen varies with lake depth and thermal stratification, http://www.michigan.gov/documents/deq/wb-npdes-DissolvedOxygen_247232_7.pdf. However, the amount of dissolved oxygen may actually increase in winter, as decreasing lake ice allows light into the water and photosynthesis can occur, producing oxygen. The atmosphere Spring and fall turnover events mix water and allow oxygen in the upper level of the lake (epilimnion) to mix into the deeper portions of the lake (hypolimnion).