Credits
Glenn Merrick and Kent Montgomery developed this lesson.

Goals
Students will learn about the relationship between dissolved oxygen (DO) concentrations and water temperature and the limits oxygen concentration and water temperature may impose on fish species.

Introduction
This lesson introduces students to the basic relationship between dissolved oxygen (DO) concentrations and water temperature. Students use that information as they determine whether a lake association should stock lake trout (Salvelinus namaycush)into Ice Lake. This lesson builds on familiar observations, such as bubbles forming in a glass of water as it warms and minnows dying in a bait bucket when water isn’t changed. Students explore the ability of lake trout to survive in a specific environment.

Students can meet the goals for this lesson by completing a directed study or an inquiry lesson.

The directed study lesson consists of a student worksheet that analyzes oxygen solubility and temperature. Students will need to print the worksheet.

* The directed study lesson is found in the student section of WOW under the title: "Studying Fish Stocking Decisions."

The student inquiry lesson places students as Minnesota Department of Natural Resources fisheries biologists. Students collect and analyze data and develop a final presentation. The instructor specifies the format of the final presentation: written paper, oral presentation, poster, or multi-media presentation. They need to print directions for the student inquiry lesson.

* The student inquiry lesson is found in the student section of WOW under the title: "Investigating Fish Stocking Decisions."

Outcomes
Students will:

1. Describe and graph the basic relationship between oxygen solubility and water temperature.
2. Explain the physical basis for declining O₂ concentration with increasing temperature.
3. Graph oxygen/temperature profile.
4. Use real data to make decisions about the suitability of specified lakes for fish species given the physiological limits of the species.

Keywords
Oxygen, solubility, temperature, lake trout

Prerequisites
There are no prerequisites, but basic graphing skills and knowledge of abiotic environmental factors help students complete the lesson successfully.

Materials/Resources/Software
Printed copies of "Studying Fish Stocking Decisions" (for directed study lesson)

Access to the Internet to retrieve WOW data

Time Required
1-2 hours

Curriculum Connections
Biology - abiotic factors, fish physiology, stratification, thermocline
Chemistry - oxygen solubility, non-polar gas, saturation
Resource Management - fish stocking, lake associations

WOW Curriculum Links
Thermal Stratification, The Effect of Photosynthesis and Respiration on Aquatic Chemistry, Properties of Water, Aquatic Respiration

Procedure
Students can meet the goals for this lesson plan by completing a directed study or an inquiry lesson. Students may want the directions for their lessons printed.

* The directed study lesson is found in the student section of WOW under the title: "Studying Fish Stocking Decisions."

* The inquiry lesson is found in the student section of WOW under the title: "Investigating Fish Stocking Decisions."

Knowledge Base
The WOW data visualization tools can help illustrate changes in DO and temperature during an extended period of sampling. These changes could be demonstrated by advancing the Profile Plotter through several sampling periods or by creating graphs in Excel (see Figures 1-3). You may want to display these for the students. This could be done either during your initial discussions for this lesson, or as part of the discussion and closure for the lesson.

Figure 1. Ice Lake DO and temperature on 6/9/99

Figure 2. Ice Lake DO and temperature on 7/6/99

Figure 3. Ice Lake DO and temperature on 8/15/99

Directed Study and Student Inquiry
Discuss the students’ knowledge of fish, focusing on the survival needs of lake trout. What water qualities are necessary for lake trout to survive in a given lake? What factors need to be considered before stocking a lake? What social and economic issues are related to stocking? What can happen if a lake is "incorrectly" stocked?

Experimental Design

Directed Study
Divide students into pairs to work on the lesson. The students need in-class work time where they can retrieve WOW data to complete the worksheet.

Student Inquiry
Present the Minnesota Department of Natural Resources fisheries biologist scenario to students. As fisheries biologists, students need to determine whether or not to stock Ice Lake with lake trout. They should use DO and temperature to make the decision about stocking.

Data Collection

Directed Study
Students use WOW temperature and DO levels for Ice Lake after an analysis of temperature and oxygen concentrations for Mackinaw Lake (provided on the worksheet).

Student Inquiry
Students need to decide how they will use WOW data to answer the question of whether or not to stock. They should choose as many dates as they feel necessary for data on temperature and DO in Ice Lake.

Data Management and Analysis

Directed Study and Student Inquiry
Students graph DO and temperature. Remind students to label axes and include titles and legends on their graphs.

Interpretation of Results

Directed Study
When the presentations are over the class should play the role of the Lake Association and discuss the feasibility of stocking before voting on whether or not to stock lake trout in Ice Lake.

Student Inquiry
Students should explore the lake survey data of the Minnesota Department of Natural Resources (http://www.dnr.state.mn.us/lakefind). Ask students to consider the physical characteristics of Clearwater, Greenwood, Saganaga, and Seagull Lakes (all in Cook County). Lake trout lakes are most common in Northeastern Minnesota, but even there lake trout are near the southern edge of their range.

Students should come to a conclusion about stocking lake trout in Ice Lake. They need to be able to explain the reasoning behind their decision.

Reporting Results

Directed Study
When the students have completed the lesson, call on at least two groups to present their findings. Ask the rest of the class to serve as area fishermen who want to know why the DNR has chosen to stock or not stock lake trout in Ice Lake.

Student Inquiry
Students need to make a presentation to concerned anglers about the ability of lake trout to survive in Ice Lake. The data and analysis should provide most of the information needed to complete the report. Specify the presentation format: a written paper, an oral presentation, a poster, or multi-media presentation. Remind students to be prepared to answer any questions about their research findings.

Evaluation
The completed data tables and graphs demonstrate students’ ability to retrieve and present temperature data from a lake using WOW. Completion of the worksheet or the final presentation provides evidence of their level of understanding of the conceptual material contained in the lesson.

Resources
Minnesota Department of Natural Resources Lakefinder

Extensions
Explore the Minnesota Department of Natural Resources (http://www.dnr.state.mn.us/lakefind) lake survey data in greater detail.