Lake Layers: Stratification. INSTITUTION Ohio State Univ., Columbus

DOCUMENT RESUME

ED 372 908 SE 053 447

AUTHOR Brothers, Chris; And Others TITLE Lake Layers: Stratification. INSTITUTION Ohio State Univ., Columbus. Ohio Sea Grant Program. SPONS AGENCY National Oceanic and Atmospheric Administration (DOC), Rockville, Md. National Sea Grant Program.; Ohio State Univ., Columbus. School of Natural Resources. REPORT NO EP-028-S; EP-028-T PUB DATE 91 CONTRACT NA90AA-D-SG496 NOTE 40p. AVAILABLE FROM Ohio Sear Grant Publications, The Ohio State University, 1314 Kinnear Road, Columbus, OH 43212-1194. PUB TYPE Guides Classroom Use Instructional Materials (For Learner) (051) Guides Classroom Use Teaching Guides (For Teacher) (052)

EDRS PRICE MF01/PCO2 Plus Postage. DESCRIPTORS Class Activities; *Educational Games; Environmental Education; Graphs; Habitats; Instructional Materials; Intermediate Grades; Junior High Schools; Learning Activities; Teaching Guides; Temperature; *Thermal Environment; *Water; *Water Quality IDENTIFIERS Great Lakes; *Hypoxin; Oxygen; *Stratification

ABSTRACT This teacher guide and student workbook set contains two learning activities, designed for fifth through ninth grade students, that concentrate on lake stratification and water quality. Ii the activities students model the seasonal temperature changes that occur in temperate lakes and observe the resulting stratification of lake waters. Students then relate stratification to water quality within the lake. As prerequisites for these activities, it is recommended that students be able to record data in chart form and prepare graphs of temperature versus depth. In addition, they should be able to use a scale to weigh a flask of water, to read. thermometers, and to measure with rulers; they should also be somewhat familiar with perimeter and area. The teacher's guide includes additional information to aid in processing the activities. Extension activities are provided along with suggested references, review questions and student worksheets. (MCO)

Reproductions supplied by EDRS are the best that can be made from the original document. *********************************************************************** EP-028T wig Lake Layers: Stratification OHIO SEA GR ANT Chris Brothers, David A. Culver, & Rosanne W. Fortner CO LL E GE The Ohio State University PROGRAM

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U II DEPARTMENT OF EDUCATION Ohhce of Educalional Research and Improvement SUMMER (layering) EDUCATIONAL RESOURCES INFORMATION CENTER IERICI Th.s document has been reproducedas rece.ve0 from the person ororgamtahon 0EAGLS orvnahno rt to .mprove OCEANIC ..'"-- O0 Mtnor changes have been made reproduchon cluahlY E DUCATION trhs docu .r...nt. of we* ot oonor,s stated tn &five! * mem do not necessantv represent PERMISSION TO REPRODUCE THIS ACTIVITIES FOR OE RI Posaton or polCyt * MATERIAL HAS BEEN GRANTED BY f, L7REAT LAKES nI...) ?Adaz1z1.6-2--/laszLifjS CFIOOLS 0 TEACHER GUIDE

TO THE EDUCATIONAL PEGOURCES INFORMATION CENTER (ERIC)." BEST COPYAVAILABLE 2 OEAGLS EP-028T 1111111 OHIO SEA Teacher Guide GRANT Completed December 1991 COLLEGE PROGRAM

This instructional activity was prepared by project E/AID-2,OSURF Account 722670. Ohio Sea Grant College Program is partially supported through grantNA90AA-D-SG496 from the National Sea Grant College Program of the National Oceanic and AtmosphericAdministration (NOAA), US. Department of Commerce. Support is provided by the Ohio Board of Regents, TheOhio State University, other participat- ing universities, and industries. Funding support was alsoprovided by The Ohio State University's School of Natural Resources and College of Education. Any opinions,findings, conclusions, or recommendations expressed herein are those of the authorS, and do not necessarilyreflect the views of NOAA or the University.

Activity A was adapted from: Vallentyne, J. R. 1967. A simplified model of a lake for instructional use.Journal of Fisheries Research Board of Canada. 24:2473-9, and Foley, Arlene F. 1984. 'Summer Stratification and Fall OverturnIn a Jar,"Journalof College Science Teaching, Sept. - Oct., 1984.

Rosanne W. Fortner, Education Program Director Victor J. Mayer, Research Coordinator Lorien Marshall, Initial Layout Editor Suzanne Abbati, Final Layout Designer and Illustrator Maran Brainard, Production Coordinator

The U.S. Government is authorized to produce and distribute reprintsfor governmental purposes notwithstanding any copyright notation that may appear hereon. MN LAKE LAYERS: STRATIFICATION (EP-028T) OHIO SEA Teacher Guide* GRANT COLL EGE By Chris Brothers, David A. Culver, and Rosanne W. Fortner PROGRAM The Ohio State University Overview: In this investigation, students will model the seasonal temperature changes that occur in temperate lakes and observe the resulting stratification (layering) of lake waters. Students will then relate stratification of Lake Erie to water quality within the lake. Prerequisite Student Background: Students should be able to record data in chart form and prepare graphs of temperature versus depth (examples are provided). They should be able to use a scale to weigh a flask of water, to read thermometers, and to measure with rulers. They should be somewhat familiar with perimeter and area.

Objectives: When the students have completed this investigation they should be able to:

1. describe how water temperature affects water density;

2. explain how changes in water temperature and density cause stratification of lake waters;

3. describe how stratification of lake waters can influence water quality; and

4. explain how phosphorus affects oxygen levels in lakes.

Materials: Activity A: An aquarium (approximately 40.0 x 20 x 25 cm) containing cold tap water, sieve or aquarium net, several pounds of ice, heat lamp, seven thermometers, small rubber bands, two plasticrulers, masking tape, small fan, 'food coloring, 300 ml flask, 300 ml beaker, colored ice (with food coloring added before freezing). Students must wear safety glasses during this activity. Activity B: Worksheets and diagrams of anoxic areas in Lake Erie, ruler, string. Activity C: a ruler and string.

Suggested Approach: Activity A: Set up the aquarium, heat lamps, and thermometers before the class period. Attach the" thermometers with rubber bands horizontally across the pair of rulers at depths of 1, 3, 5, 9, 13, 17, and 21 cm. Suspend the rulers with attached thermometers vertically in the aquarium and securewith masking tape to the front of the aquarium (see diagram). The heat lamp should be located directly over the middle of the aquarium, 20 - 25 cm above the water surface you will need to adjust thisheight for the lamp that you use. The colored ice will also need to be prepared ahead of time.For activity A, students may work in groups of varying sizes depending on the availability ofsupplies. Optimum group size is three to five students. This activity win take approximately onehour. Activity B: Students can work on this activity as individuals or in small groups.The question sheets may be completed in class, as a homework assignment, or as a class discussion. Activity B should takeapproximately 45 minutes.

*Note: Information for teachers is enclosed in boxes in this guide.

iT 1111111 LAKE LAYERS: STRATIFICATION (EP-028T) OHIO SEA Teacher Guide GR ANT COLL EGE By Chris Brothers, David A. Culver, and Rosanne W. Fortner PROGRAM The Ohio State University

Introduction:

Have you ever been swimming in the ocean or a lake and stepped into a deep area where the water was much colder? Why does colder water stay near the bottom of a lake? Every year, deep lakes in the temperate zones of the world go through water temperature changes as the seasons change. In the Great Lakes, the water may go from an icy winter condition to temperatures as high as 24°C (75°F) or more. What is occurring in the lake when this happens, and how are the plants and animals in the lake affected?

Objectives:

When you have completed this investigation you should be able to:

I. describe how water temperature affects water density;

2. explain how changes in water temperature and density cause stratification of lake waters;

3. describe how stratification of lake waters influences water quality; and

4. explain how phosphorus affects oxygen levels in lakes.

Heat lamp (behind if on a stand or clamped to topc aquarium)

1111111111111 1111111111111111C .1111111111111111111C 1111111111111111111111 111111111111111111111111 .111111111111111111111111111[...... ", 111011111111111111 11111111111C >Glass

Rulers (taped on to the aquarium) Thermometers held on by rubberbands)

2T Activity A: How do the Great Lakes change through the seasons?

Materials: A better simulation of seasons and layers can be achieved An aquarium containing cold tap wa:.er, sieve or by blowing a fan or low powered hair dryer across the aquarium net, ice, heat lamp, seven thermometers, surface while the lamp is on. The warmth of the surface rubber bands, two plastic rulers, masking tape, layer will be distributed to a depth of several centimeters. small fan, food coloring, 300 ml flask, 300 ml beaker, colored ice (frozen with food coloring added). Safety F.While you wait, pour 250 ml of ice water into glasses must be worn at all times during this a 300 ml flask. Weigh the flask. activity. 1.What is the temperature and weight of this water?

Procedure: --A-;;;;; will V-a-ry--.Cie-pen-c-linger-l-t-he-terni-)e;n-re-ofhe A. Add enough ice, stirring occasionally, to the water. aquarium to lower the temperature of the water to 4°C. You should still have a shallow layer G. Empty the flask and refill it with 250 ml of 1,,ery of ice on the surface where the temperature will hot tap water. Weigh the flask with th2 hot be 0°C. Allow the water to come to rest. In the water and record its weight. first column of the temperature data chart on your worksheet, record the temperatures of the 2.What is the temperature and weight of this seven thermometers. water?

B. Remove the rest of the ice with a sieve or Answers will vary depending on the temperature ofthe-1 aquarium net as gently as possible. Turn on the water. heat lamp. Be very careful not to splash any water on the heat lamp or it will explode. 3.Which temperature of water weighs morn? Record this time as the beginning of the experi- The cold water weighs more. The actual difference mea- ment. sured will be very low, however (perhaps 2 g. difference, depending on the accuracy of volume measurements.) If C. After 5 minutes, record the temperatures of student level is lower or the equipment is not sophisti- each of the seven thermometers in the second cated, it may not be possible to detect differences in density this way. Water is most dense at 4°C. It becomes column of your data chart. less denseas temperature increa se from 4°C. It alsobecomes less dense as temperatures decrease from 4°C to 0°C, at D. As you wait for the 5 minutes to pass, graph which point it freezes. This is why warm layers of water depth in cm versus temperature in °C on graph rest on top of cold layers during the summer and why #1 using the data from column #1. What time cold water sinks in the fall during fall turnover. of year do these temperatures represent? Label the graph with the time of year. H. Pour the hot water into a beaker or glass jar. ------Gently add a few colored ice cubes to the hot This represents winter before the spring turnover. Tem- water. perature at most depths should be about 4°C with the surface water at about 0°C. 4.What happens to the colored water from the ice as the ice melts? Why? E.At the 12 minute mark, record the temperatures on the seven thermometers in the third column Ice floats on water because it is less dense than water. As of your data chart. Record the water tempera- the ice melts, its colored water will sink because it is colder than the warm tap water. Eventually a cold layer of water tures again at the 30 minute and 45 minute will form at the bottom of the warm water, illustrating marks in the fourth and fifth columns of your the stratification that occurs in lakes. data chart.

3T Spring turnover occurs when water temperatures from this column tO graph depth in cm versus at the surface are equal to those at lower depths temperature in °C on graph #3. What season and water from all depths mixes. The top layers should you label this graph? of water may then start to warm slightly. Data in column five best represent the stratified summer lake. Temperatures will be warmest at the surface, coldest I. Which column of temperature data best repre- at the bottom, and may show a sharp drop at some depth sents spring turnover in your model lake? Use in between. This sharp drop occurs at the metalimnion. the data from this column to graph depth in cm This graph should be labeled "summer stratification." versus temperature in °C on graph #2. Label this graph "spring turnover." 6. What is the temperature in the epilimnion? In the hypolimnion? How much tempera- File data in column two probably best represent spring ture difference is there between these two turnover. The temperatures should be the same over all layers? depths or slightly warmer at the surface. Temperatures in the epilimnion (surface) may be 20°C or As summer a pproaches, the la kecon tinues to warm. higher. Temperatures in the hypolimnion (bottom) may be about 5-8°C. Temperature differences may be 15°C or 5. Why do surface temperatures increase dur- more. ing the summer while water temperatures at lower depths remain cold? When temperature layers form in the lake in the summer the warm surface water (epilimnion) is Surface temperatures increase from warming by the sun separated from the cold bottom water (hynolim- and from the surrounding ai.Not as much sunlight reaches the lower depths, thus these areas are not warmed nion) by the metalimnion. Temperature is not the as much. only factor that is different among the layers. Oxy- gen dissolves better in cold water than in warm During the summer, the lake becomes stratified water, but it is getting used up by living things all into three layers of waterthe warm upper layer the time. Wind at the surface of the lake creates or epilimnion (epi = upon or above), the cold waves and stirs up the water, adding oxygen to it in bottom layer or hypolimnion (hypo = lower or the same way a bubbler works in a fish tank. The below), and the middle layer of rapid temperatuie metalimnion acts as a barrier. It keeps oxygen in the change known as the metalimnion(meta=middle). 'ace waters from reaching the colder waters of the hypolimnion. Gradually, the oxygen in the hy- J. Which temperature data column best repre- polimnion can get used up. sents the stratified summer lake? Use the data

Depth Time Columns in cm #1 #2 #3 #4 #5 #7 1 0 8 10 13 15 13 7

3 4 7 9 12 15 13 7

4 6 7 8 9 9 7

9 4 6 6 7 7 7 7

13 4 6 6 7 7 7 7

17 4 6 6 6 7 7 7

21 4 6 6 6 6 7 L6

4T 7. What happens to the animals living at the Fall turnover mixes the water in the lake. This mixing bottom of the lake when there is no oxygen? resupplies oxygen and other nutrients needed by animals and plants to all depths in the lake. These animals may die from lack of oxygen or may be forced to move to areas of the lake where there is more 10. What seasonal chaige in lake temperatures oxygen (surface or near shore waters.) has happened in the fall? Are there any As autumn begins, the surface waters of the lake temperature layers in the lake once the wa- begin to cool. ter has mixed? Fall turnover has occurred. There should be no tempera- K. Turn off the heat lamp. Turn on the fan and use ture layers in the lake -- temperatures should be fairly ft to create a strong wind by blowing on the similar at all depths. water from one direction. Keep blowing until all the water in the lake is completely mixed. L.Carefully add ice to the surface water to create Record the water temperatures in the sixth col- an ice layer. Try not to mix or disturb the water. umn of your data chart. Record the water temperatures in the last column of your data chart. 8. Why do surface waters of the lake cooi off during the fall? 11. What time of year is represented by these temperature data in the last column? Surface water temperatures cool during the fall as less sunlight reaches and warms them. In addition, air over [These temperature data represent late fall as water tem-1 the lake is cooler and the lake gives up heat to the air. peratures cool and ice starts to form on the lake. Fall turnover occurs when all the lake water has M. Use the data from the last column to graph cooled and has been completely mixed by water depth in cm versus temperature in °C on graph movements and wind. #4. What should this graph be labeled? 9. How might fall turnover be good for ani- This graph should be labded "fall turnover" or "late fall." mals living at the bottom of the lake?

Stratifie4 Lake Thermal stratification of a temperate zone lake

HEATING

ICE COVER

4°

SIF 4° 74°

WINTER SPRING SUMMER FALL (turnover) (layering) (turnover)

ST Activity B: How does stratification affect water quality? 1 Some of Lake Erie's water quality problems have C. Repeat step 2 for the enlarged diagrams of the been related to the layering of the lake's waters, lake in 1964, 1973, 1976, and 1982. Enter the which occurs in the summer months. During the perimeter of the anoxic part of the lake for each summer, the warm surface layer of water does not year in the chart on your worksheet. mix with the colder bottom layer of water. If a lot of algae has grown in the lake, decay of the dead algae D. Using the steps for finding the area of a circle on the lake bottom may use up all of the oxygen in from its circumference, find the area of the the cold bottom water layer. When there is no anoxic section of the lake from its perimeter. oxygen in the bottom waters, the water is said to be The formula you should use is A=C2/41t anoxic. Fish and other animals cannot live in these (Tc=3.14). anoxic waters. In the fall, the surface water cools and mixes with the bottom water, resupplying the Although the anoxic section is not a perfect circle in bottom water with oxygen needed for life. shape, we will use this method to estimate the area of the anoxic part of the lake from the perimeter you Materials: measured. Enter the area of the anoxic part of the Worksheet and diagrams of anoxic areas in Lake lake for each year in the chart on your worksheet. Erie, ruler, string. 3.In which year did the lake have the largest Procedure: anoxic area? In which year did it have the A. Look at the anoxia diagrams of Lake Erie on smallest anoxic area? How do these results your worksheet. The shaded area on each dia- compare to your earlier predictions? gram shows the part of the lake bottom that was anoxic tliat year. These parts of the lake con- The lake had the largest anoxic arca in 1973. The smallest tained no oxygen in the hypolimnion. anoxic area occurred in 1930. E. Look at the map of Lake Erie divided into its 1.In which year do you think the lake had the three geographic basins: the Eastern, Central, largest anoxic area? In which year does the lake seem to have had the smallest anoxic and Western basins. Match the basins on this area? map with your map of the lake showing anoxic areas. IThelake had the largest anoxic area in 1973. The samllest anoxic arca occurred in 1930 4.In which basin of the lake are the anoxic L __ areas found? B. On an enlarged diagram from your teacher use the string and ruler method to measure the Anoxic areas are found in the Central Basin. The small perimeter of the anoxic part of the lake in 1930. black dots in the Western Basin are islands, not anoxic Stretch the string all the way around the perim- areas. eter (outer edge) of the shaded anoxic part. 5.Looking at the map of Lake Erie divided Then stretch the string along the ruler to mea- into basins, what is the average depth in sure its length in cm. The length oi the string is each of the three basins? equal to the perimeter of the anoxic part of the lake. You may want to tape the string in place at Average depth in the lake in the Eastern Basin is 80 feet your starting point or mark your starting point (24 meters), the Central Basin, 60 ft. (18m), and the Western with your pencil. Basin, 24 ft. (7m).

2.What was the perimeter of the anoxic sec- Usually only large lakes that are deeper than 40 feet tion in J930? or 12 meters stratify into temperature layers during the summer. [The perimeter of the anoxic section is 4 cm.

6T Three Basins of Lake Erie

(Adapted from Department of the Interior, "Lake Erie Report," Washington, D.C.,1968)

,40

Pi )0611601113

03110 TRUK,'

WESTERN BASIN EASTERN BASIN

20 MIAN DIM l 40 40 14160 orTil NO AO 100 120 140 160 160 Lake Erie Longitudinal Cross-Section 200 220

6.Which of the three basins in Lake Erie will it is so deep. Deep waters are cold, while shallow stratify in the summer? waters are warm. Cold water can hold much more oxygen than warm water can. The Eastern and Central Basin will stratify. The supply of oxygen in the cold waters of the 7.Does the Western Basin stratify during the Eastern Basin at the beginning of the summer is summer? Why or why not? Will it become high. Oxygen at the bottom of the lake is used anoxic? throughout the summer by animals living there The Western Basin does not become anoxic because it does and in the decay of dead algae. Stratification of the not stratify. lt is shallow enough that oxygen is continually lake's waters prevents more oxygen from reaching mixed and supplied to all depths of the lake by wind and the bottom water. Even so, the oxygen supply in the wave action. Eastern Basin does not get used up during the summer, because the supply was very high at the 8.Is the Central Basin deeper or shallower beginning of the summer, and because the hy- than the Eastern Basin? Which of the two polimnion is much thicker in the Eastern Basin than basins will have warmer bottom waters? it is in the Central Basin. Which of the two basins will have less oxygen in its bottom waters at the beginning of 9.What might happen to fish and other ani- the summer? Which of the two basins is mals living in the Central Basin when it more likely to become anoxic? becomes anoxic?

The Central Basin is shallower than the Eastern one, its Fish and other animals cannot live in anoxic waters. They bottom waters are warmer, and these waters contain less may die from suffocation or they may move to areas of the oxygen at the beginning of the summer. The hypolimnion lake that still contain oxygen. There may be a change in the may only be about 1 tn. deep. Thus, the Central Basin is kinds of fish living in the lake from species needing cold, more likely to become anoxic. high oxygen waters (trout and whitefish) to fish that can survive in warmer waters with less oxygen (carp). Although the Eastern Basin stratifies during the summer, it does not become anoxic. This is because

0 The farm fertilizers and the laundry detergents we Great Lakes Basin to limit the amount of phospho- use both contain a chenlical called phosphorus. rus that could be used in detergents. When fertilizers from farms or sewage containing detergents flow into a lake, phosphorus enters the 12. Why do you think laws banning phospho- lake as well. Phosphorus is a nutrient needed by all rus in detergents were passed? plants, including algae, to grow. When a large Such laws, called phosphorus bans or limits, were passed amount of phosphorus enters a lake, it may cause to reduce the amount of phosphorus entering the lakes. It algae to grow very rapidly. The result may be too was hoped that by reducing the amount of phosphorus much algae. The algae may use up the dissolved entering the lakes, algae growth and anoxic areas could oxygen (D.O.) in the water, both through their own also be reduced. growth and as they decay. The amount of phosphorus entering Lake Erie has been reduced nearly 60 percent in the past twenty 10. What happens to the lake when growth and years. decay of algae uses up all the oxygen? 13. How would you now explain why the size rThe lake becomes anoxic. of anoxic areas in the lake seems to have People started putting phosphorus into detergents decreased since 1976?

1; in the late 1950s. Before that, phosphorus was not Reducing the amount of phosphorus entering the lake has used in detergents. contributed to a reduction in algae growth in the lake. ' With less algae growth in the lake, smaller areas of the lake IL How would you now explain the large became anoxic during the 1980s. anoxic areas that occurred in Lake Erie during the 1970s? How can you explain the In January of 1990, the State of Ohio joined other smaller anoxic areas that occurred in 1930 Great Lakes states that have reduced phosphorus in and 1964? detergents.

rLarge anoxic areas in the 1970s probably resulted from 14. Predict what will happen to the anoxic area large amounts of phosphorus from laundry detergents of Lake Erie in the 1990s if phosphorus entering the lake. In 1970 half of the phosporus in sewage continues to be reduced in the lake.

came from laundry detergents. The smaller anoxic areas . . . in 1930 occurred before phosphates came into use. Al- As less phosphorus enters Lake Eric, anoxic areas of the though phosphates were being used by 1960, not as much lake should decrease in size. However, phosphorus will phosphorus had entered the lake by 1960 as it had by the still be entering Lake Erie from farm runoff and other 1970s. sources. In 1978, laws were passed by many states in the

0 Phosphorus Sunlight penetration decreases (sewage & fertilizers)

Algae increase Fish species 0 change Algae die

Dissolved Oxygen (13.0.) used up

8T Ideas for Extension Suggested References 1.Nutrients in the Great Lakes, OEAGLS activity num- Herdendorf, Charles E. "Recovering from Phosphorus ber EP-29, includes two activities related to eutrophi- Enrichment." The Great Lake Erie, Rosanne W. Fortner cation and water quality in the Great Lakes. Students and Victor J. Mayer, editors. The Ohio State University investigate the impact of nutrients in a lake by observ- Research Foundation, 1987. ing algae growth in samples of lake water and plot the Oglesby, Ray T. "Lakes Which Produce Too Much." The amounts of nutrients reaching a lake following a storm Conservationist. June-July, 1970. to learn about the role of wetlands in improving water Reutter, Jeffrey M., Frank R. Lichtkoppler, and Charles E. quality. Herdendorf. "Lake Erie: Phosphorus and Eutrophica- 2. Have students check the phosphorus content of the tion." Ohio Sea Grant Fact Sheet # 15. detergents their families use. Most brands include this Vallentyne, John R. The Algal Bowl: Lakes and Man. Depart- iniormation in the list of ingredients. Which deter- ment of the Environment Fisheriesand MarineService, gents contain the most and the least amounts of phos- Ottawa, Canada, 1974. phorus? 3. Have students research the farming practices used in their area. What is no-till agriculture? Arc any farmers using it? What are the advantages and disadvantages of no-till? Students could interview farmers or county Soil and Water Conservation District staff to find out.

9T Review Questions

1. How does water temperature affect water den- 7. How does phosphorus contribute to anoxia in sity? Lake Erie?

[ Colder water is denser and heavier than warmer water. Phosphorus is a nutrient needed by algacto grow. When phosphorus enters a lake, it acts as a fertilizer, causing algae to grow rapidly. The algae may use up the oxygen 2.When water is stratified in a lake, where is the in the water both through its own growth and as it colder water found? Why? decays.

In a lake, cold water is denser and will sink while warm 8. Why have Great Lakes states passed laws limit- water is less dense and will "float" on top of the cold ing the amount of phosphorus that can be used water. Therefore, the cold water will be found at the in detergents? bottom of the lake. Phosphorus limits or bans were passed to reduce the 3.What are the names given to the three layers of amount of phosphorus entering the lakes and thus water that form when a lake is stratified? reduce algae growth and problems caused by anoxia.

Epilimnion, hypoliminion, and inetalimnion. Detergent phosphorus limits (70P) in Great Lakes basin.

Area %P Starting 4. How does stratification affect the amount of Date oxygen found in the bottom of the lake? Ontario 2.2 1973 When the lake is stratified, the rnctalimnion acts as a Chicago, Ill. 0.5 1972 barrier keeping water from mixing and oxygen from Indiana 0.5 1973 reaching the hypolimnion. Oxygen in the hypolimnion Michigan 0.5 1977 may get used up,:suiting in anoxia. Minnesota 0.5 1977 New York 0.5 1973 Wisconsin 0.5 1979 5. Why does the Western Basin of Lake Erie not Ohio (lake basin) 0.5 1990 become anoxic during the summer? Pennsylvania no limitations

The Western Basin does not stratify during the summer 1

because it is too shallow. Wind and wave action con- 1 tinually mix the water in the lake. Because oxygen is supplied to all depths, thebasin does not become anoxic.

6. What are the human-produced sources of phosphorus nutrients entering the lakes?

Phosphorus enters a lake primarily from run-off of fertilizers from farms and from laundry detergent.

ti 1OT OHIO SEA Lake Layers: Stratification (EP-028T) GR ANT Answer Sheet COLL EGE PROGRAM

Activity A: How do the Great Lakes change through the seasons?

1.What is the temperature of the ice water in the flask?

What is the flask's weight with cold water?

2.What is the temperature of the hot tap water in the flask?

What is the flask's weight with hot tap water?

3.Which temperature of water is heavier? (compare the flask weights)

4.What happens to the colored water from the ice as the ice melts?

Why?

5. Why do surface water temperatures increase during the summer while water temperatures atlower depths remain cold?

6.What is the temperature in the epilimnion of your lake?

In the hypolimnion?

How much temperature difference is there between these two layers?

7.What happens to the animals living at the bottom of the lake when there is no oxygen?

8. Why do surface water temperatures of the lake cool during the fall?

9. How might fall turnover be good for animals living at the bottom of thelake?

10. What seasonal change in lake temperatures has happened in thefall?

Are there any temperature layers in the lake once the water hasmixed?

11. What time of year is represented by the temperature data inthe last column?

11T -I; Water Temperature Graphs

Graph #1(from Data Chart column #1) Graph #2 (from Data Chart column #2) Spring Season Winter Season

0 0

0,4 8 a.)

12 12

16 16

20 20

I I I 10 12 14 16 0 2 4 6 8 10 12 14 16 Temperature °C Temperature °C

Graph #3 (from Data Chart column #5) Graph #4 (from Data Chart column #7)

Season Summer Season Fall

20 0 20

6 8 10 12 14 16 6 8 10 12 14 16 Temperature °C Temperature °C

12T MOM OHIO SEA Lake Layers: Stratification (EP-028T) GR ANT Answer Sheet COLLEGE PROGRAM

Activity B: How does stratification affect water quality?

1.In which year do you think the lake had the largest anoxic area?

In which year does the lake seem to have had the smallest anoxic area?

2.What was the perimeter of the anoxic section in ',930?

YEAR 1930 1964 1973 1976 1982 F PERIMETER r- ANOXIC AREA

3.In which year did the lake have the largest anoxic area?

In which year did it have the smallest anoxic area?

How do these results compare to your earlier predictions?

4.In which basin of the lake are the anoxic areas found?

5.What is the average or mean depth in each of the three basins?

Eastern Central Western

6.Which of the three basins in Lake Erie will stratify in the summer?

7.Does the Western Basin stratify?

Why or why not?

Will it become anoxic?

8.Is the Central Basin deeper or shallower than the Eastern Basin?

Which of the two basins will have warmer bottom waters?

Which of the two basins will have less oxygen in its bottom waters at the beginning of the summer?_

Which of the two basins will most likely become anoxic?

13T L 9.What might happen to fish and other animals living in the Central Basin when it becomes anoxic?

10. What happens to the lake when growth and decay of the algae uses up all the oxygen?

11. How would you now explain the large anoxic areas that occurred in Lake Erie during the 1970s?

How can you explain the smaller anoxic areas that occurred in 1930 and 1964?

12. Why do you think laws banning pl-osphorus in detergents were passed?

13. How would you now explain why the size of anoxic areas in the lake seems to have decreased since

1976?

14. Predict what will happen to the anoxic area of Lake Erie in the 1990s if phosphorus continues to be

reduced in the lake.

14T Worksheet for Activity B

15T c."") Anoxia Diagrams of Lake Erie 1930-1982

16T Anoxia diagrams of Lake Erie

e"..-- 1,0 k i 17T Anoxia diagrams of Lake Erie

1973

-.wow

1976 Anoxia diagrams of Lake Erie

19T 1..1 Oceanic Education Activities for Great Lakes Schools(0EAGLS) Results of studies of student knowledge about the oceans and Great Lakes environments indicate a needfor greater awareness of those environments, and a greater understanding of the impact they have upon the lives of people.OEAGLS (pronounced "eagles") are designed to take a concept or idea from the existing school curriculum and develop it into an oceanic andGreat Lakes context, using teaching approaches and materials appropriate for children in grades fivethrough nine. OEAGLS materials are designed to be easily integrated into existing curricula. Investigations arccharacterized by subject mauer compatibility with existing curriculum topics, short activities lastingfrom one to three classes, minimal preparation time, minimal equipment needs, standard page size for easy duplication, student workbookplus teacher guide, suggested extension activities for further information or creative expression, teachability demonstrated by usein middle school class- rooms; and content accuracy assured by critical reviewers. Each titleconsists of a student workbook and a teacher guide and costs $3.00 for the publication, postage, and handling. If orderingEP-026, add an additional $4.00 to cover the cost of the computer disk.

THE EFFECT OF THE GREAT LAKES ON TEMPERATURE (EP-001)THE ESTUARY: A SPECIAL PLACE (EP-016) THE EFFECT OF THE GREAT LAKES ON CLIMATE (EP-002) THE GREAT LAKES TRIANGLE (EP-017) ANCIENT SHORES OF LAKE ERIE (EP-003) KNOWING THE ROPES (EP-018) HOW TO PROTECT A RIVER (EP-004) GETTING TO KNOW YOUR LOCAL FISH (EP-019) CHANGING LAKE LEVELS (EP-00S) SHIPPING: THE WORLD CONNECTION (EP-020) EROSION ALONG THE GREAT LAKES (EP-006) WE HAVE MET THE ENEMY (EP-021) COASTAL PROCESSES AND EROSION (EP-007) IT'S EVERYONE'S SEA: OR IS IT? (EP-022) POLLUTION IN LAKE ERIE: AN INTRODUCTION (EP-008) PCBs IN FISH: A PROBLEM? (EP-023) YELLOW PERCH IN LAKE ERIE (EP-009) A GREAT LAKES VACATION (EP-024) EVIDENCE OF ANCIENT SEAS IN OHIO (EP-010) STORM SURGES (EP-025) TO HARVEST A WALLEYE (EP-011) RIVER TREK with computer program (EP-026) OIL SPILL! (EP-012) WAVES (EP-027) SHIPPING ON THE GREAT LAKES (EP-013) LAKE LAYERS: STRATIFICATION (EP-028) GEOGRAPHY OF THE GREAT LAKES (EP-014) NUTRIENTS IN THE GREAT LAKES (EP-029) OHIO CANALS (EP-015) EATING LIKE A BIRD (EP-030)

0EAGLets In the primary grade range we have three activities. All use Lake Eric informationapplied to all primary subject areas. Each title costs $5.00 for the publication, postage, and handling. LAKE ERIETAKE A BOW (EP-031) BUILD A FISH TO SCALE (EP-032) A DAY IN THE LIFE OF A FISH (EP-033)

COMPUTER PROGRAMS All programs run on Apple II computer series. EP-24/Disk This program is an optional purchase to accompany OEAGLS A GREAT LAKESVACATION. $4.00 EP-74/Disk To accompany OEAGLS EP-011, 019, 021, and 023. $5.00

ADDITIONAL EDUCATIONAL MATERIALS SUPPLEMENTAL CURRICULUM ACTIVITIES TO ACCOMPANY HOLLING C.HOLLING'S PADDLE-TO-THE-SEA (EP-076) $10.00 ACTIVITIES FROM MIDDLE SEA (EP-071) S2.50 WATERWORKS (EP-072) $2.50 THE OHIO SEA GRANT EDUCATION PROGRAM: DEVELOPMENT,IMPLEMENTATION, EVALUATION (EP-075) $8.00 MARINE EDUCATION BIBLIOGRAPHY $2.00

OTHER PUBLICATIONS AVAILABLE TWINE LINE Sea Grant eight-page bimonthly newsletter. $4.50 for six issues. PUBLICATION BROCHURE Free. EDUCATION BROCHURE Free. TECHNICAL PUBLICATIONS BROCHURE Free. SEA GRANT PROGRAM BROCHURE Free. GREAT LAKES PURSUIT SE. Pflaurner and R.W. Fortner. A game playedlike Trivial Pursuit ® but the questions challenge players to learn about the Great Lakes. $24.00 (Reduced price available for educators.) TOO MUCH MUSSEL 1991. This 5 1/2 minute video (VHS format)provides an overview of the zebra mussel impact to Lake Eric. $15.00 GLOBAL CHANGE IN THE GREAT LAKES SCENARIOS 1991.Ten scenarios about global change in the Great Lakes. $6.00 23 T -H E OHIO SFATE UNIVERSITY

Ohio Sea Grant College Program The Ohio State University 1314 Kinnear Road Columbus, OH 43212-1194 Tel. 614/292-8949 Fax 614/292-4364 (Send all publication requests to thisaddress.)

For information about the education program, contactthe Ohio Sea Grant Education Coordinator, Dr. RosanneW. Fortner, at The Ohio State University (59 Rarnseyer Hall, 29 W. Woodruff Avenue,Columbus, OH 43210-1077, 6141292-1078).

Dr. Jeffrey M. Reutter, Ohio Sea GrantDirector EP-028S

OHIO SEA Lake Layers: Stratification GR ANT /Ins Brothers, David Cuiver. r Rosanne IV. rortner CO LLEGE The Ohio State University PROGRAM

1VINTER SPRING (turnover)

4°C 4°C 22°C 21 C 8°C 11 +'KC 7°C A7°C + 6°C 6°C 11 6°C

FALL (turnover) SUMMER (layering) OEAGLS OCEANIC EDUCATION ACTIVITIES FOR GREAT LAKES S CHOOLS STUDENT WORKBOOK lag OEAGLS EP-028S 0410 SEA Student Workbook ANT Completed December 1991 COLL EGE PROGRAM

This instructional activity was prepared by project E/ AID-2,OSURF Account 722670. Ohio Sea Grant College Program is partially supported through grantNA90AA-D-SC496 from the National Sea Grant College Program of the National Oceanic and AtmosphericAdministration (NOAA), U.S. Department of Commerce. Support is provided by the Ohio Board of Regents, TheOhio State University, other participat- ing universities, and industries. Funding support was alsoprovided by The Ohio State University's School of Natural Resources and College of Education. Any opinions,findings, conclusions, or recommendations expressed herein are those of the authors, and do not necessarilyreflect the views of NORA or the University.

Activity A was adapted from: Vallentyne, J. R. 1967. A simplified model of a lake for instructional use.Journal of Fisheries Research Board of Canada. 24:2473-9, and Foley, Arlene F. 1984. "Summer Stratification and Fall OverturnIn aJar," Journal of College Science Teaching, Sept. - Oct., 1984.

Ohio Sea Grant Education Ohio Sea Grant College Program The Ohio State University The Ohio State University 059 Ramseyer Hall 1314 Kinnear Road 29 West Woodruff Avenue Columbus, OH 43212-1194 Columbus, OH 43210 614/292-8949 614/292-1078 Rosanne W. Fortner, Education Program Director Victor J. Mayer, Research Coordinator Lorien Marshall, Initial Layout Editor Suzanne Abbati, Final Layout Designer and Illustrator Maran Brainard, Production Coordinator

Permission is hereby granted to educators to reproduce the material from the studentworkbook (only) for educational purposes. The U.S. Government is authorized to produce and d istribute reprints for governmental purposesnotwithstanding anycopyright notationthat may appear hereon. 111111LAKE LAYERS: STRATIFICATION (EP-028S) OHIO SEA Student Workbook GR ANT COLLEGE By Chris Brothers, David A. Culver, and Rosanne W. Fortner PROGRAM The Ohio State University

Introduction:

Have you ever been swimming in the ocean or a lake and stepped into a deep area where the water was much colder? Why does colder water stay near the bottom of a lake? Every year, deep lakes in the temperate zones of the world go through water temperature changes as the seasons change. In the Great Lakes, the water may go from an icy wintercondition to temperatures as high as 24°C (75°F) or more. What is occurring in the lake when this happens, and how are the plants and animals in the lake affected?

Objectives:

When you have completed this investigation you should be able to:

I.describe how water temperature affects water density;

2.explain how changes in water temperature and density cause stratification of lake waters;

3.describe how stratification of lake waters influences water quality; and

4.explain how phosphorus affects oxygen levels in lakes.

Heat lamp (behind if on a stand or clamped to top of aquarium)

1111111111111C " 1111111111111111C 11111111111111111111I 11111 1111111111111111 10111111111111111111111...... : .... 11111111111111111111111-1111' 1111111111111 111111111 111111C Glass

Rulers (taped on to the aquarium) Thermometers (held on by rubberbands)

is Ad Activity A: How do the Great Lakes change through the seasons?

Materials: G. Empty the flask and refill it with 250 ml of very An aquarium containing cold tap water, sieve or hot tap water. Weigh the flask with the hot aquarium net, ice, heat lamp, seven thermometers, water and record its weight. rubber bands, two plastic rulers, masking tape, small fan, food coloring, 300 ml flask, 300 ml beaker, 2.What is the temperature and weight of this colored ice (frozen with food coloring added). Safety water? glasses must be worn at all times during this

activity. . 3.Which temperature of water weighs more?

Procedure: H. Pour the hot water into a beaker or glass jar. A. Add enough ice, stirring occasionally, to the Gently add a few colored ice cubes to the hot aquarium to lower the temperature of the water water. to 4°C. You should still have a shallow layer of ice on the surface where the temperature will 4.What happens to the colored water from the be 0°C. Allow the water to come to rest. In the ice as the ice melts? Why? first column of the temperature data chart on your worksheet, record the temperatures of the Spring turnover occurs when water temperatures seven thermometers. at the surface are equal to those at lower depths and water from all depths mixes. The top layers B. Remove the rest of the ice with a sieve or of water may then start to warm slightly. aquarium net as gently as possible. Turn on the heat lamp. Be very careful not to splash any I. Which column of temperature data best repre- water on the heat lamp or it will explode. sents spring turnover in your model lake? Use Record this time as the beginning of the experi- the data from this column to graph depth in cm ment. versus temperature in °C on graph #2. Label this graph "spring turnover." C. After 5 minutes, record the temperatures of each of the seven thermometers in the second As summer approaches, the lake continues to warm. column of your data chart. 5. Why do surface temperatures increase dur- D. As you wait for the 5 minutes to pass, graph ing the summer while water temperatures depth in cm versus temperature in °C on graph at lower depths remain cold? #1 using the data from column #1. What time of year do these temperatures represent? Label During the summer, the lake becomes stratified the graph with the time of year. into three layers of waterthe warm upper layer or epilimnion (epi = upon or above), the cold E.At the 12 minute mark, record the temperatures bottom layer or hypolimnion (hypo = lower or on the seven thermometers in the third column below), and the middle layer of rapid temperature of your data chart. Record the water tempera- change known as the metalimnion (meta = middle). tures again at the 30 minute and 45 minute marks in the fourth and fifth columns of your J.Which temperaiure data column best repre- data chart. sents the stratified summer lake? Use the data from this column to graph depth in cm versus F.While you wait, pour 250 ml of ice water into temperature in °C on graph #3. What season a 300 ml flask. Weigh the flask. should you label this graph?

1.What is the temperature and weight of this 6.What is the temperature in the epilimnion? water? In the hypolimnion? How much tempera-

2S ture difference is there between these two Record the water temperatures in the sixth col- layers? umn of your data chart.

When temperature layers form in the lake in the 8. Why do surface waters of the lake cool off summer the warm surface water (epilimnion) is during the fall? separated from the cold bottom water (hypolimnion) by the metalimnion. Temperature is not the Fall turnover occu:s when all the lake wa ter has only factor that is different among the layers. Oxy- cooled and has been completely mixed by water gen dissolves better in cold water than in warm movements and wind. water, but it is getting used up by living things all the time. Wind at the surface of the lake creates 9. How might fall turnover be good for ani- waves and stirs up the water, adding oxygen to it in mals living at the bottom of the lake? the same way a bubbler works in a fish tank. The 10. What seasonal change in lake temperatures metalimnion acts as a barrier. It keeps oxygen in the surface waters from reaching the colder waters of has happened in the fall? Are there any the hypolimnion. Gradually, the oxygen in the hy- temperature layers in the lake once the water has mixed? polimnion can get used up. L.Carefully add '.ce to the surface water to create 7.What happens to the animals living at the an ice layer. Try not to mix or disturb the water. bottom of the lake when there is no oxygen? Record the water temperatures in the last column of your data chart. As autumn begins, the surface waters of the lake begin to cool. 11. What time of year is represented by these temperature data in the last column? K. Turn off the heat lamp. Turn on the fan and use it to create a strong wind by blowing on the M.Use the data from the last column to graph water from one direction. Keep blowing until depth in cm versus temperature in °C on graph all the water in the lake is completely mixed. #4. What should this graph be labeled?

Stratified. Lake Thermal stratification of a temperate zone lake

Ilk.HEATING

ICE COVER

WINTER SPRING SUMMER FALL (turnover) (layering) (turnover)

3S Activity B: How does stratification affect water quality?

Some of Lake Erie's water quality problems have lake seem to have had the smallest anoxic been related to he layering of the lake's waters, area? which occurs in the summer months. During the summer, the warm surface layer of water does not B.On an enlarged diagram from your teacher use mix with the colder bottom layer of water. If a lot of the string and ruler method to measure the algae has grown in the lake, decay of the dead algae perimeter of the anoxic part of the lake in 1930. on the lake bottom may use up all of the oxygen in Stretch the string all the way around the perim- the cold bottom water layer. When there is no eter (outer edge) of the shaded anoxic part. oxygen in the bottom waters, the water is said to be Then stretch the string along the ruler to mea- anoxic. Fish and other animals cannot live in these sure its length in cm. The length of the string is anoxic waters. In the fall, the surface water cools equal to the perimeter of the anoxic part of the and mixes with the bottom water, resupplying the lake. You may want to tape the string in place at bottom water with oxygen needed for life. your starting point or mark your starting point with your pencil.

Materials: 2.What was the perimeter of the anoxic sec- Worksheet and diagrams of anoxic areas in Lake tion in 1930? Erie, ruler, string. C.Repeat step 2 for the enlarged diagrams of the Procedure: lake in 1964, 1973, 1976, and 1982. Enter the A. Look at the anoxia diagrams of Lake Erie on perimeter of the anoxic part of the lake for each your worksheet. The shaded area on each dia- year in the chart on y our worksheet. gram shows the part of the lake bottom that was anoxic that year. These parts of the lake con- D.Using the steps for finding the area of a circle tained no oxygen in the hypolimnion. from its circumference, find the area of the anoxic section of the lake from its perimeter. 1.In which year do you think the lake had the The formula you should use is A=0/4ir (7r=3.14). largest anoxic area? Tn which year does the

Three Basins of LakeErie (Adapted from Department of the Interior, "Lake Erie Report," Washington, D.C.,1968)

DETROrt

ERE NEW YOAV

PE NNSYLVANLI

10LEDD CLEVELAND

CENTRAL BASIN EASTERN BASIN

20 MEAN DEVT1111' 40 11040 ',Frill 40 Z/0 MEAN Dort LI la AO 100 120 140 160 180 Lake Erie Longitudinal Cross-Section 200 220 4S Although the anoxic section is not a perfect circle, basins will have warmer bottom waters? we will use this method to estimate the area of the Which of the two basins will have less oxy- anoxic part of the lake from the perimeter you gen in its bottom waters at the beginning of measured. Enter the area of the anoxic part of the the summer? Which of the two basins is lake for each year in the chart on your sheet. more likely to become anoxic?

3.In which year did the lake have the largest Although the Eastern Basin stratifies during the anoxic area? In which year did it have the summer, it does not become anoxic. This is because smallest anoxic area? How do these results it is so deep. Deep waters are cold, while shallow compare to your earlier predictions? waters are warm. Cold water can hold much more oxygen than warm water can. E. Look at the map of Lake Erie divided into its three geographic basins: the Eastern, Central, The supply of oxygen in the cold waters of the and Western basins. Match the basins on this Eastern Basin at the beginning of the summer is map with your map of the lake showing anoxic high. Oxygen at the bottom of the lake is used areas. (See previous page.) throughout the summer by animals living there and in the decay of dead algae. Stratification of the 4.In which basin of the lake are the anoxic areas found? lake's waters prevents more oxygen from reaching the bottom water. Even so, the oxygen supply in the 5.Looking at the map of Lake Erie divided Eastern Basin does not get used up during the into basins, what is the average depth in summer, because the supply was very high at the each of the three basins? beginning of the summer, and because the hypolimnion is much thicker in the Eastern Basin than Usually only large lakes that are deeper than 40 feet it is in the Central Basin. or 12 meters stratify into temperature layers during the summer. 9.What might happen to fish and other animals living in the Central Basin when it 6.Which of the three basins in Lake Erie will becomes anoxic? stratify in the summer? The farm fertilizers and the laundry detergents we 7.Does the Western Basin stratify during the use both contain a chemical called phosphorus. summer? Why or why not? Will it become When fertilizers from farms or sewage containing anoxic? detergents flow into a lake, phosphorus enters the lake as well. Phosphorus is a nutrient needed by all 8.Is the Central Basin deeper or shallower plants, including algae, to grow. When a large than thck Eastern Basin? Which of the two amount of phosphorus enters a lake, it may cause

0 Phosphorus Sunlight penetration decreases (sewage & fertilizers)

Algae increase Fish species 0 change Algae die

Dissolved Oxygen (D.O.) used up

5S algae to grow very rapidly. The result may be too 12. Why do you think laws banning phospho- much algae. The algae may use up the dissolved rus in detergents were passed? oxygen (D.O.) in the water, both through their own growth and as they decay. The amount of phosphorus entering Lake Erie has been reduc,:d nearly 60 percent in the past twenty 10. What happens to the lake when growth and years. decay of algae uses up all the oxygen? 13. How would you now explain why the size People started putting phosphorus into detergents of anoxic areas in the lake seems to have in the late 1950s. Before that, phosphorus was not decreased since 1976? used in detergents. In January of 1990, tl 2 State of Ohio joined other 11. How would you now explain the large Great Lakes states that have reduced phosphorus anoxic areas that occurred in Lake Erie dur- in detergents. ing the 1970s? How can you explain the smaller anoxic areas that occurred in 1930 14. Predict what will happen to the anoxic area and 1964? of Lake Erie in the 1990s if phosphorus continues to be reduced in the lake. In 1978, laws were passed by many states in the Great Lakes Basin to limit the amount of phosphorus that could be used in detergents.

Review Questions

1. How does water temperature affect water density?

2. When water is stratified in a lake, where is the colder water found? Why?

3.What are the names given to the three layers of water that form when a lake is stratified?

4. How does stratification affect the amount of oxygen found in the bottom of the lake?

5. Why does the Western Basin of Lake Erie not become anoxic during the summer?

6.What are the human-produced sources of phosphorus nutrients entering the lakes?

7. How does phosphorus contribute to anoxia in Lake Erie?

8. Why have Great Lakes states passed laws limiting the amountof phosphorus that can be used in detergents?

6S t.)) OHIO SEA Lake Layers: Stratification (EP-028S) GR ANT Worksheet COLL EGE PROGRAM NAME

Activity A: How do the Great Lakes change through the seasons?

1.What is the temperature of the ice water in the flask?

What is the flask's weight with cold water?

2.What is the temperature of the hot tap water in the flask?

What is the flask's weight with hot tap water?

3.Which temperature of water is heavier? (compare the flask weights)

4.What happens to the colored water from the ice as the ice melts?

Why?

5. Why do surface water temperatures increase during the summer while water temperatures at lower depths remain cold?

6.What is the temperature in the epilimnion of your lake?

In the hypolimnion?

How much temperature difference is there between these two layers?

7.What happens to the animals living at the bottom of the lake when there is no oxygen?

8. Why do surface water temperatures of the lake cool during the fall?

9. How might fall turnover be good for animals living at the bottom of the lake?

10. What seasonal change in lake temperatures has happened in the fall?

Are there any temperature layers in the lake once the water has mixed?

11. What time of year is represented by the temperature data in the last column? Water Temperature Data Chart °C

Depth Time Columns in cm #1 #2 #3 #4 #5 #6 #7 1

8S 0 '.-1 Water Temperature Graphs

Graph #1 Graph #2 Season Season

4,4 CI)

Temperature °C Temperature °C

Graph #3 Graph #4 Season Season

ra4

Temperature °C Temperature °C 9S NMI OHIO SEA Lake Layers: Stratification (EP-028S) GR ANT Worksheet COLL EGE fROGRAM NAME IIIIININIIIM111111111111111111111

Activity B: How does stratification affect water quality?

1.In which year do you think the lake had the largest anoxic area?

In which year does the lake seem to have had the smallest anoxic area?

2.What was the perimeter of the anoxic section in 1930?

YEAR 1930 1964 1973 1976 1982

PERIMETER

ANOXIC AREA

3.In which year did the lake have the largest anoxic area?

In which year did it have the smallest anoxic area?

How do these results compare to your earlier predictions?

4.In which basin of the lake are the anoxic areas found?

5. What is the average or mean depth in each of the three basins?

Eastern Central Western

6.Which of the three basins in Lake Erie will stratify in the summer?

7.Does the Western Basin stratify?

Why or why not?

Will it becomeanoxic?

8.Is the Central Basin deeper or shallower than the Eastern Basin?

Which of the two basins will have warmer bottom waters?

Which of the two basins will have less oxygen in its bottom waters at the beginning of the summer?

Which of the two basins will most likely become anoxic?

lOs 9.What might happen to fish and other animals living in the Central Basin when it becomes anoxic?

10. What happens to the lake when growth and decay of the algae uses up all the oxygen?

11. How would you now explain the large anoxic areas that occurred in Lake Erie during the 1970s?

How can you explain the smaller anoxic areas that occurred in 1930 and 1964?

12. Why do you think laws banning phosphorus in detergents were passed?

13. How would you now explain why the size of anoxic areas in the lake seems to have decreased since

1976?

14. Predict what will happen to the anoxic area of Lake Erie in the 1990s if phosphorus continues to be

reduced in the lake. Worksheet for Activity B

12S Oceanic Education Activities for Great Lakes Schools (OEAGLS) '.esults 01 studies 01 student knowledge about the oceans and Great Lakes environments indicate a need tor greater awareneN, of those environments, and a greater understanding of the impact they have upon the lives of people.OEAGLS (pronounced "eagles") are designed to take a concept or idea from the existing school curriculum and develop it into an oceanic andGreat Lakes context, using teaching approaches and materials appropriate for children in grades livethrough nine. OEAGLS materials are designed to be easily integrated into existing curricula. Investigations are characterized by Nuhiect matter compatibility with existing curriculum topics, short activities lastingtrom one to three classes, minimal preparation ume, minimal equipment needs, standard page size for easy duplication, studentworkbook plus teacher guide, suggested extension activities for further information or creative expression, teachabilitydemonstrated by use in middle school class- rooms; and content accuracy assured by critical reviewers. Each title consistsof a siudent workbook and a teacher guide and costs 53.00 for the publication, postage, and handling. If orderingEP-026, add an additional S4.00 to cover the cost of the computer disk.

THE EFFECT OF THE GREAT LAKES ON TEMPERATURE (EP-001)THE ESTUARY: A SPECIAL PLACE (EP-016) THE EFFECT OF THE GREAT LAKES ON CLIMATE (EP-002) THE GREAT LAKES TRIANGLE (EP-017) ANCIENT SHORES OF LAKE ERIE (EP-003) KNOWING THE ROPES (EP-018) HOW TO PROTECT A RIVER (EP-004) GETTING TO KNOW YOUR LOCAL FISH (EP-019) . CHANGING LAKE LEVELS (EP-005) SHIPPING: THE WORLD CONNECTION (EP-020) EROSION ALONG THE GREAT LAKES (EP-006) WE HAVE MET THE ENEMY (EP-021) COASTAL PROCESSES AND EROSION (EP-007) IT'S EVERYONE'S SEA: OR IS r? (EP-022) POLLUTION IN LAKE ERIE: AN INTRODUCTION (EP-008) PCBs IN FISH: A PROBLEM? (LP-023) YELLOW PERCH IN LAKE ERIE (EP-009) A GREAT LAKES VACATION (EP-024) EVIDENCE OF ANCIENT SEAS IN OHIO (EP-010) STORM SURGES (EP-02S) TO HARVEST A WALLEYE (EP-011) RIVER TREKwith computer piogram(EP-026) OIL SPILL! (EP-012) WAVES (EP-027) SHIPPING ON THE GREAT LAKES (EP-013) LAKE LAYERS: STRATIFICATION (EP-028) GEOGRAPHY OF THE GREAT LAKES (EP-014) NUTRIENTS IN THE GREAT LAKES (EP-029) OHIO CANALS (EP-015) EATING LIKE A BIRD (EP-030)

OEAGLets In the primary grade range we have three activities. All use Lake Erie information applied toall primary subject areas. Each title costs S5.00 for the publication, postage, and handling. LAKE ERIETAKE A BOW (EP-031) BUILD A FISH TO SCALE (EP-032) A DAY IN THE LIFE OF A FISH (EP-033)

COMPUTER PROGRAMS All programsrunon Apple II computer series. EP24/DlskThis program is an optional purchase to accompany OEAGLS A GREAT LAKESVACATION. S4.00 EP-74/DlskToaccompany 0EAGLS EP-011, 019, 021, and 023. S5.00

ADDITIONAL EDUCATIONAL MATERIALS SUPPLEMENTAL CURRICULUM ACTIVITIES TO ACCOMPANY HOLLING C.HOLLING'S PADDLE-TO-THE-SEA (EP-076) S10.00 ACTIVITIES FROM MIDDLE SEA (EP-071) S2.50 WATERWORKS (EP-072) $2.50 THE OHIO SEA GRANT EDUCATION PROGRAM: DEVELOPMENT,IMPLEMENTATION, EVALUATION (EP-075)S8.00 MARINE EDUCATION BIBLIOGRAPHY S2.00

OTHER PUBLICATIONS AVAILABLE TWINE LINESea Grant eight-pagebimonthlynewsletter. $4.50 for six issues. PUBLICATION BROCHURE Free. EDUCATION BROCHURE Free. TECHNICAL PUBLICATIONS BROCHURE Free. SEA GRANT PROGRAM BROCHURE Free. GREAT LAKES PURSUIT S.E. Pflaumer and R.W. Fo,tner. Agame played likeTrivial Pursuit IDbut the questions challenge players to learnabout the Great Lakes. $24.00(Reduced priceavailable foreducators.) TOO MUCH MUSSEL1991. This 5 1/2 minute video (VHS format) provides anoverview of the zebra mussel impact to Lake Erie. S15.00 GLOBAL CHANGE IN THE GREAT LAKES SCENARIOS 1991.Ten scenarios about global change in the Great Lakes. $6.00 H F. OH IO S FAIT UN t VERcTry

Ohio Sea Grant College Program The Ohio State University 1314 Kinnear Road Columbus, CH 43212-1194 Tel. 614/292-8949 Fax 614/292-4364 (Send all publication requests to this address.)

For infon-nation about the education program, contact thc Ohio Sca Grant Education Coordinator, Dr. Rosanne W. Fortner, at The Ohio State University (59 Ramscycr Hall, 29 W. Woodruff Avenue, Columbus, OH 43210-1077, 614/292-1078).

Dr. .1e0-rey M. Rcutter. Ohio Sea Grant Director