Century High School

Unit 2 Ecology

Biology 2016-2017 Century High School

Name ______Hour ______Teacher ______Biosphere

Biotic Factors

Abiotic Factors

Population

Biological Community

Ecosystem

Biosphere

Habitat

Community Interactions

Competition

Predation

Symbiosis

1. Commensalism

2. Mutualism

3. Parasitism

2 Autotroph any organism that absorbs the sun’s energy for food

Heterotroph Get energy from consuming other organisms

Herbivore eat only plants

Carnivore eat meat

Omnivore eats both plants and animals

Detritivore eats fragments of dead matter

Trophic Levels-means each step in a food level or chain

Food chain model that shows how energy flows through an ecosystem

Food Web a model representing multiple interconnected food chains and pathways in which energy flows

3 Ecological Pyramids Energy, Biomass, and Numbers

Primary Producers Plants

Consumers anything that uses producers for energy

Decomposer Break down dead material

Biochemical Cycles

Hydrologic Cycles

Watershed

Condensation

Precipitation

Transpiration

Phosphorus cycle

4 ***Eutrophication*****

Carbon cycle and Oxygen cycle

Photosynthesis Respiration Combustion

Nitrogen Cycle

5 Community Ecology

Community – a group of interacting ______that occupy the same area at the same time.

Example – Rochester

A. Limiting Factors – Any abiotic or biotic factor that restricts

1. Abiotic

2. Biotic

B. Range of Tolerance - The range between the upper and lower limit of abiotic and biotic factors in which an organism can survive.

Ecological Succession – When one community replaces another as a result of changing abiotic and biotic factors.

A. Primary Succession – The establishment of a community where?

Symbiosis: lichens and mosses

B. Secondary Succession – The establishment of a community after a community has been removed but the soil is intact. When???

Climax Communities---A climax community occurs when there is no longer change. Ex: lichens and mosses can live on rock -> these die and become soil -> plants and animals live on the soil -> Climax Community.

6 Community

Limiting Factors

Range of tolerance

Ecological Succession

Primary Succession

Climax Community

Secondary Succession

Biomes (These are NOT part of the standards for HS but can be covered)

Chapter 4

Population Density

Population Distribution (dispersion)

Gains and Losses in Population Size

1. Immigration

2. Emigration

3. Mortality

4. Natality

7 Exponential Growth (J Curve)

Doubling Time:

Biotic Potential

Limiting Factors

Carrying Capacity (S curve)

Density Dependent Control

Density Independent Factors

8 Life History Patterns

r-strategists – type 3 (many offspring)

k-strategists – type 1 (few offspring)

1. Type I

2. Type II

3. Type III

Human Population Growth (demography)

Trends in Human Population

1. Zero population growth

2. Age Structure

3. Human Carrying capacity

How did we as a population get so big?

9 What will happen in the Future?

A. Density Dependent Factors?

B. Density Independent factors?

Chapter 5

Biodiversity

Extinction

Genetic Diversity

Species diversity

Ecosystem Diversity

Importance of biodiversity

1. Economics

2. Indirect economic value

3. Aesthetic and Scientific Value

10 Threats to Biodiversity

Extinction Rates

Background extinction verses mass extinction

Factors that threaten biodiversity

Overexploitation

Habitat loss

Fragmentation of habitat

Pollution

Acid precipitation

Eutrophication

Introduced species (Invasive Exotics)

11 Food Web Simulation

Purpose: This activity is designed to give students a hands-on intuitive perspective of the energy loss within the food web.

Materials: 1. 5 gallon bucket filled with water 2. 21 plastic cups with holes drilled in the bottom and around the sides at ½ inch intervals 3. Signs or stickers indicating animal assignment in the food chains 4. Smaller buckets for water collection 5. Measuring devices (beaker, graduated cylinder) for recovered water measurement.

Possible Food Webs:

Phytoplankton  Krill  Baitfish  Dolphin  Shark  Benthic worm

Grain  Mouse  Fox  Owl  Bobcat  Decomposing Bacteria

Or Make up your own to reflect the interest of students

How to Play this Game

Assign one student to play the role of the sun. This student is in charge of the 5 gallon bucket of water (may be 2 if the class is large) and will hold the bucket at an accessible angle during play. Pass out signs indicating food web placement to each of 21 students (add another chain if the class is large). Form lines around the sun in the order given so that all Primary consumers are dipping energy directly from the source (the sun). The students will form food chains of various lengths. The object of the game is for students to pass energy (water) along the food chain and into the bucket at the end of the line to represent the passing of energy in a food chain much like a bucket brigade. However, there are holes in the cups. Any energy that is used up by an animal in the process of metabolism, physical energy or non-consumable parts such as bones or scales is represented by the water that escapes out of these holes. (Students are not allowed to cover up these holes). If enough students are available it is advisable to assign a student as a counter in each chain to keep track of the amount of energy originally obtained from the sun. Otherwise, the phytoplankton will need to keep track of the number of times they fill their cup with energy from the sun.

At the end of the game students will return to the classroom to measure the amount of water (energy) which was successfully passed along the chain and compare it to the amount that was originally obtained from the sun. They will then calculate the percentage of energy that was actually preserved in the food chain. After the calculations the students will graph their results. Essentially, the longer the food chain, the less of the original energy made it to the end of the food chain. This illustrates the basic form of the energy pyramid and why the numbers need to be so much higher on the bottom with producers as so much energy is lost as it makes its way to the top (10 percent rule).

12 Activity adapted from: Community of Life, “Applications in Biology/Chemistry”, CORD Communications, Waco TX, 1994.

Map of Play

SUN Grain

Grain Grain Mouse Grain Grain Grain Mouse Fox Mouse Mouse Mouse Fox Owl Fox Fox Owl Cat Owl Cat Bacteria

Data Collection and Calculations 1 Cup=250ml

Food Chain Amount of Amount of End / Sun Percent of the Number Energy from the collected energy X 100 Energy Sun (ml) at the end (ml) Recovered

13 DATA VISUAL REPRESENTATION

Graph the Recovery of energy in this food chain. This will show the relationship between the length of the food chain and the energy transfer efficiency. Put the % of energy transfer on the Y axis and the food-chain length on the X axis.

Questions

1. What does water in the five-gallon bucket represent in an ecosystem?

2. What does water you receive from another food-chain species represent?

3. What does spilled water represent?

4. What does water in the end container represent?

14 5. Consider all “energy” that was lost to the food chain during the activity. In an actual ecosystem how would this energy be used?

DISCUSSION

1. If you were living in a country without enough food and you were the president of this country, how might you relieve some of their food problem? Which foods would best put energy into the people?

2. In this country of plenty, we often eat from the top of the food chain. Can you see any problem with that as far as the ecosystem is concerned?

3. Where does all of our energy come from? Hint: Have you eaten anything that wasn’t at one time alive? Where did it get its energy?

4. Currently we are using fossil fuels as our energy source outside of our bodies. Where did this energy ultimately come from?

15 The Lynx Eats the Hare

The Hare and Lynx are a classic predator prey interaction. Today you will be conducting a simulation to show how the two populations intermix. To begin start with 3 hares (spatially dispersed), toss the lynx into the square. If the lynx captures 3 hares it will reproduce and have 1 offspring (for a total of 2 lynx). If it does not capture 3, it will die and one will move in for the next generation to replace it. Every surviving hare has an offspring each generation. Tally 25 generations.

Generation Number Number Hares Hares Lynx Lynx Lynx Of Of Lynx Eaten Remaining Starved Surviving Offspring Hares (Total) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

16 Graph: Lynx/Hare Population per Generation

Graph Paper #2

17 Questions

1. What are other examples of variables (besides predators) that may influence hare population?

2. What pattern does the lynx population follow?

3. What would happen to the hare population if there were no lynx?

4. Give an example of a wild animal that no longer has a predator to control its population.

5. What would cause the hare population to grow exponentially?

6. Why is it useful to graph these populations for analysis?

7. How would hare emigration affect the lynx population?

18 Pond Ecosystem Lab

The presence or absence of certain organisms, or indicator species, reveals much about the quality of the water. Some macroinvertebrates are extremely sensitive to changes in water quality and are found in large amounts, in waters that are generally clean or unpolluted by organic wastes and have more oxygen. Other macroinvertebrates are not sensitive to pollution; therefore if a large number of these organisms are found in a sample it would serve as an indicator of poor water quality.

Good Water Fair Water Poor Water______

Mayfly lavae Crayfish Midge fly larvae Caddisfly larvae Riffle beetle larvae Blackfly larvae Stonefly largae Dragonfly Leeches Gilled snails Cranefly larvae Aquatic worms Riffle beetle – adult Damselfly Lung snails Planaria Scuds Water Penny Alderfly Hellgramite Sowbug Watersnipe fly Whirligig beetle larvae Fishfly Clam or mussel

Macro-organism survey Procedure: Each group will have 20 minutes to collect as many macro-organisms as possible. We will return to class and identify organisms today and tomorrow and will compose a list of all organisms found in the pond. Sketch and identify 5 of your organisms below:

19 Class Species list:

______

Micro-organism Survey Procedure: Micro-organisms are microscopic. Each group will use their collection water from the macros to identify as many microorganisms as possible. We should be able to find various types of organisms including daphnia, insect larvae, protests, small crustaceans and other micros. Sketch 5 of your organisms.

Class Species list:

______

Biochemistry:

As a class determine the following values using the kits supplied by your teacher.

Dissolved Oxygen______Nitrates______pH ______Phosphates______

20 Questions:

1. Which of the above chemical test values are most likely to cause eutrophication in your pond?

2. What happens to the dissolved oxygen in the pond if eutrophication is taking place?

3. Why does eutrophication change the amount of dissolved oxygen in a pond?

4. What could cause the pH to become more acidic in a water ecosystem?

5. What natural buffer do we have to protect us from decreasing (or increasing) pH levels?

21 How Many Bears Can Live in This Forest? Project Wild

Although black bears were once found through most of North America, today their range is much smaller. In Minnesota, black bears are found primarily in the forested northeast and north-central regions of the state. Because bears travel over large areas, especially when food is scarce, reports of bears outside their usual range in the state are not uncommon.

Full-grown males are large, weighing 115-160 Kg. (250-350 pounds), during the summer and more in the fall. Males, called boars, are solitary except during the breeding period in early summer (June to mid-July). Females, or sows, are smaller, weighing about 55-100 Kg. (120-220 pounds). When food is plentiful sows generally breed every two years. However, when food is scarce, successful breeding may only occur every third or fourth years. Sows give birth to cubs, usually 2-3, while still in their den in winter. Cubs generally remain with their mother until the spring of their second year.

Until 1971 the black bear was not protected in Minnesota. In fact, there was a bounty on bears until the mid-1960’s. Today the number of bears in the state is regulated largely by the hunting season. Population goals for bears in Minnesota are set at a level to ensure a healthy, viable population through the black bear range, providing enough bears for viewing and hunting while preventing excessive nuisance and damage problems. Each year the number of hunting permits issued is adjusted for different areas of the state. Estimates of annual food availability are used to help interpret the sometimes wide yearly fluctuations in the success rates of bear hunters and in the age and sex of bears killed during the hunting season.

Food Habits

Black bears are omnivores, which means they eat both plants and animals. Their primary food are fruits, nuts and insects. Other foods such as flowers, buds and green vegetation are eaten when primary foods are not available. Meat is a minor part of their diet. Bears will occasionally kill livestock and deer, particularly newborn fawns. Bears will also eat carrion (dead animals) when available. Because foods are not available for bears year-round they hibernate during the winter. Bears spend a great deal of the time fattening themselves before hibernation. Bears lose 15-30 percent of their weight while hibernating. Fat layers provide energy and help insulate them from the cold. Their fat stores continue to provide much of their energy during the weeks after they awaken in the spring when food is still scarce.

The first foods available to bears in the spring are grasses, leafy plants and the leaves and catkins (flowers0 of aspen trees. While young and succulent, these foods can be high in protein, but are typically low in carbohydrates and fats. In early June, as plants mature and become less nutritious, bears begin to feed intensively on several species of ants, if available. Bears then switch to berries and nuts as they ripen, usually beginning in early July. Garbage dumps are also used as a food source where available.

22 Effects of Food Availability

Differences in age of first breeding and number of years between litters have been found between bears in north-central and northeastern Minnesota. DNR researchers have found that sows in north-central Minnesota usually breed in the summer of their third and fourth year. In contrast, U.S. Forest Service researcher, Lynn Rogers, studying bears in northeastern Minnesota, found a sow’s age of first breeding was usually five or six years. Sows in the northeast often produced litters only every three or four years compared to north-central sows which usually produced a litter of cubs every other year.

These differences are most likely due to differences in the food supply available to bears in the two areas. Although many of the same foods are present in both areas, overall fruit abundance is generally lower in the northeast. Acorns, a very important fall food source for bears, are largely absent from the northeast, as are blackberries and wild plums. In early summer before berries ripen, ants dominate the diet of north-central bears but make up only a small percentage of the diet of northeast bears. Ant abundance may differ in the two areas and also contribute to the differences observed in reproduction.

In general, Rogers found a survival rate of 88% for cubs in the northeastern Minnesota that were both conceived and born during years of abundant food resources. (Conception and birth take place during separate growing seasons.) The survival rate was only 59 percent, however, for cubs that were both conceived and born in years when food was scarce. Cub survival in north-central Minnesota averaged 83 percent over a 15 year period, similar to the cub survival reported by Rogers for good food years in northeastern Minnesota. After three years of scarce food resources Rogers documented a 35 percent decline in the bear population in his study area, whereas no population changes have been linked to food availability in north-central Minnesota.

The amount of nuisance activity by bears (raiding garbage dumps, campgrounds, gardens, etc.) is also related to food availability. The years 1985, 1990 and 1995 had the poorest food availability recorded statewide since the food survey began in 1982; these same years had the highest recorded number of bears killed as nuisances. Food abundance also affects the timing of nuisance activity. For example, nuisance reports were high during the late summer in 1981 when there was a statewide failure of many fruits. However, during 1983, most bear nuisance complaints were received in early summer and then decreased as fruits and berries became available.

The availability of garbage dumps can also alter bear biology. Rogers found that the use of dumps was most important in years of poor berry crops. He also found that the use of dumps allowed individual bears to extend their growing and fattening period resulting in earlier maturation and greater reproductive success than bears that did not have frequent access to dumps.

23 Reading Analysis and Interpretation

1. Is a difference in food availability the cause of the difference in the breeding activity of bears? Why do you think this?

2. Why do we hunt black bears at all? Is it necessary to give hunting licenses?

3. In order for a bear to fatten up prior to hibernation which foods are most important to it at that time? If these foods are unavailable to the bear in a large enough quantity what will happen to the bear?

4. How is the breeding of bears different in north-east verses north-central Minnesota. List two differences? How do these differences influence the bear population in these areas? Where would you find more bears?

5. From the reading, would you say that dumps are important to bears? When are they most important to the survival of the population? How do they influence the nuisance factor for bears?

24 Survivorship

Introduction

Within a population, some individuals die very young while others live into old age. To a large extent, the pattern of survivorship is species dependent. Generally, three patterns of survivorship have been identified. These three have been summarized by survivorship curves, graphs that indicate the pattern of mortality (death) in a population.

Humans in highly developed countries with good health care services are characterized by a Type 1 curve, in which there is high survivorship until some age, then high mortality. The insurance industry has generated information to determine risk groups. The premiums they charge are based upon the risk group to which an individual belongs.

While survivorship curves for humans are relatively easy to generate, information about other species is more difficult to determine. It can be quite a trick to simply determine the age of an individual plant or animal, not to mention watching an entire population over a period of years. However, the principle of determining survivorship can be demonstrated in the laboratory using nonliving objects.

In this exercise we will study the populations of dice and soap bubbles, using them as models of real populations to construct survivorship curves. We will subject these populations to different kinds of stress to determine the effects upon survivorship curves.

Materials 15 cm ruler Bucket containing 50 dice Soap bubble solution and wand Survivorship frame Stopwatch or clock

Dice Survivorship

Work in a group of four for this experiment. One person should be assigned to dump the dice, another to record data, while the other two count.

Population 1

1. Empty the bucket of fifty dice onto the floor. 2. Assume that all individuals that come up as 1s die of heart disease. All others survive. 3. Pick up all the 1s, set them aside (in the cemetery) and count the number of individuals who have survived. Record the number of survivors in this generation (Generation 1). 4. Return the survivors to the bucket. 5. Dump the survivors onto the floor again and remove the deaths (1s) that occurred during this second generation. 6. Count and record the number of survivors. 7. Continue this process until all the dice have died from heart disease.

25 Population 2

1. Start again with a full bucket of fifty dice. Assume that the 1s die of heart disease and 2s die of cancer. Proceed as described for Population 1, recording numbers in the table until all dice are dead. 2. Now determine the percentage of survivors for each generation with the following formula: Percentage surviving = # surviving / 50 x 100 3. Plot your data on the graph paper provided. Make one graph on regular even graph paper and one graph on semi-log paper. Put both populations on one graph.

Soap Bubble Survivorship

Work in groups of four for this experiment. One person will blow bubbles, a second group member will serve as the timer, a third observes survivorship and the fourth records the data. Three different populations of soap bubbles will be formed based upon actions of group members, with each group being assigned one population to work with during this exercise.

Population 1: Once the bubble leaves the wand, group members wave, blow, or fan and effort to keep the bubble in the air and prevent it from breaking (dying).

Population 2: Group members do nothing to interfere with the bubbles or keep them up in the air.

Population 3: This group uses a wand mounted on a wooden frame. The group member blowing bubbles tries to blow the bubbles through the opening in the frame. Bubbles that break rather than passing through the frame are timed and included in the data. Bubbles that fall without passing through or breaking on the frame are ignored (not counted in the data). Do not attempt to manipulate the frame in any way so as to increase the chances that the bubbles will pass through it.

1. Practice blowing bubbles for a few minutes until they can be generated with the single end of the wand. 2. Once the bubble is free of the wand, the timer should start the watch. When the bubble bursts, the timer notes the time and puts a check mark next to the appropriate age at death in the table. 3. Obtain data on fifty bubbles 4. Summarize your data as follows: a. Count the number of checks (the number of bubbles dying) at each age. Record the number in the column marked “Total Number Dying at this Age”. b. By subtracting the number dying at each age from 50, determine and record the number surviving at each age. For example, if five bubbles broke (died) at age 1 second, then 50-5=45 survived at least 1 second.

26 c. Calculate the percentage surviving at each age. Since at birth (moment the bubble left the wand) fifty bubbles were alive, 100% were alive at age 0. Use the following formula: % surviving to this age = # surviving / 50 x 100% d. Plot the percentage surviving on the graphs. Do both straight arithmetic graphs and logarithmic plots of the survivorship.

NOTE: Make Graphs of Your Data only. We will be comparing the graphs from 3 different bubble groups and the dice group. We will then share the data in order to answer the questions in the next section. Interpretation of the Survivorship Curves

Share your data with the other groups in the class and also examine their data. Examine first the plots from the dice populations. In the first population (heart disease only), a constant one-sixth of the population dies at each age. In the second population two-sixths die at each age. As you see on the arithmetic plot these data form a smooth curve, while on the logarithmic plot they form a straight line. Both types of plots provide useful information. A straight line on a logarithmic plot indicates the death rate is constant. In the arithmetic plot it is easier to see that more individuals die at a young age than at older ages. In natural populations, three basic trends of survivorship affecting population size have been identified. Their shapes are graphed below on “regular arithmetic” graph paper.

Type 1 (I) Number of living organisms

Type 2 (II)

Type 3 (III)

Type 1 = Low mortality early in life, most deaths occurring in a narrow time span at maturity. Type 2 – Rate of mortality fairly constant at all ages Type 3 – High mortality early in life.

27 Analysis

1. How do your graphs compare with the Type I, II, and III shown?

2. Do any of the soap bubble populations show a constant death rate for at least part of their lifespan? If so, which one?

3. How did the treatments that the soap populations 1, 2, and 3 were subjected to affect the shape of the curves?

Post-Lab Questions

1. Which type of survivorship curve describes a population of organisms that produces a very large number of offspring, most of which die at a very early age, only a few surviving to old age? Give an example of a real world population of this type.

2. Would you expect a population in which most members survive for a long time to produce few or many offspring? Which would be most advantageous to the population as a whole?

3. Suppose a human population exhibits a Type III survival curve. What would you expect to happen to the curve over time if a dramatic improvement in medical technology takes place?

4. What would you expect to happen to a population whose birth rate is about equal to the death rate?

5. Returning to the survivorship model you created using dice: You found that the chance of dying from heart disease is one-sixth for each die, indicating that survivorship is essentially the same for each age group. Relate what happened in your model with a realistic projection showing at what ages most humans die of heart disease.

28 DATA CHARTS

Dice Population

POPULATION 1 POPULATION 2 (heart disease only) (cancer & heart #1 on the dice Disease) #1 and #2

Generation Number Percentage Number Percentage Surviving Surviving Surviving Surviving 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Draw double line graph here:

29 DATA CHARTS

Soap Bubbles

Age at Death Check here for Total Number Number Percentage (seconds) each bubble Dying at This Surviving to this Surviving to this dying Age Age Age 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30+ Draw triple line graph here……..

30 Rival for Survival

Exotic species are organisms that are brought into an ecosystem that is not their own. These organisms attempt to fill the niche of organisms that are already present. There is a limited amount of resources in any environment. Adding new species means that species already now have more competition for food and shelter. If an exotic species does well, it usually means a preexisting species begins to decrease in numbers through intense competition for ecosystem resources.

Exotic species have been introduced into new environments both intentionally and unintentionally. For example, purple loosestrife was introduced for landscaping purposes. Other species, such as zebra mussels, were transferred unintentionally through the ballast water of ocean freighters.

Vocabulary

Alewife

Eurasian water milfoil

Exotic species

Fishhook flea

Indigenous species

Organism

Purple loosestrife

Round goby

Sea lamprey

Zebra mussel

1. What are exotic species?

2. How do you think exotic species affect the environment?

31 3. Can you name some exotic species?

4. What are the potential problems of taking a species out of its natural habitat?

5. How did some exotic species get transported to the Great Lakes region?

Create a concept map for the term exotic species. List each exotic species and indicate its interaction and effect on native species and other exotics. Natives to include are: Walleye, Chinook Salmon, Lake Trout.

6. How do Chinook Salmon fit into this picture? Are they exotic? Where do they come from?

32 Which Fish Can We Eat?

Bioaccumulation of a toxin occurs when a toxin collects in the body of an organism. PCBs, a class or organic compounds, and DDT, a compound previously used as an insecticide, are toxins of concern in the Great Lakes, because they remain in the environment long after their use is prohibited. When some toxins (such as PCBs or DDT) are ingested, they do not pass through the body of the organism but collect and accumulate in its body. High concentrations of toxins can cause a variety of health problems, genetic disorders, and death in humans and animals. The class of toxin called PCBs (polychlorinated biphenyls) is soluble in fat, which means that it collects in fatty tissue. The family of PCBs included 209 compounds, and PCB products contain both the chemicals and added components. As fish and other organisms live in bodies of water that contain PCBs, they eat other organisms, such as plankton, which contain the toxins. As the fish ingest PCB-laden food, the toxins collect in their fatty tissue so that the concentration of PCBs in their bodies is much higher than in the water around them. The longer they live in those waters, the more toxins they accumulate from the organisms they consume. If a bird eats several fish that are contaminated with PCBs then that bird “collects” the toxins from each of the fish it eats. In this manner, the PCBs are passed up the food chain at higher and higher levels of concentration.

Some of the symptoms in humans associated with PCBs are cancer, neurological effects, and effects on reproduction and development. In wildlife, PCBs have been associated with premature deaths and effects on reproduction and the immune system. It is recommended that people not eat fish that have PCB concentrations of 2 parts per million or more.

Objectives

After completing this activity you should understand some reasons why toxic concentrations vary in fish.

Procedure

The Ohio Department of Natural Resources measured the PCB concentration in white bass and walleye in spring 1987 and fall 1987, respectively. Each was collected at three different places on Lake Erie. Table 1 has the data that was obtained.

White Walleye Bass Size Maumee Cedar Sandusky Size Middle Cedar Lorain Bay Point Bay Sis Isl. Point 9-10.9” 1.34ppm 0.66 0.74ppm 14-17.9” 0.16 0.16 0.15 11-12.9” 1.27 0.93 0.91 18-21.9” 0.25 0.24 0.22 13” + 1.64 0.96 1.06 22” + 0.33 0.35 0.42

33 1. Using Table 1 and the graph below, construct a bar graph of the data from Sandusky Bay for white bass (concentration of PCB vs. size of fish.

2. Construct another bar graph with the data from Middle Sister Island for walleye.

3. Answer the following questions a. How is fish size related to PCB content for the white bass at Sandusky Bay?

b. Is the relationship between size and PCB content the same for the walleye at Middle Sister Island?

c. What could cause this relationship?

d. Now examine the data from the other sites. Does the relationship seem to hold for fish taken at each site?

34 e. Compare the data collected for the concentration of PCBs in white bass and walleye. Which species contains higher concentrations of PCBs? When comparing the data, be careful to note the size categories. The walleye samples were larger than the white bass. Remember, PCB concentration should increase with size because PCBs bioaccumulate (i.e., contrite in fatty tissues as fish become larger and older).

f. Why might the concentration of PCBs be lower in walleye compared to white bass?

State of Ohio Advisory Meal Advice for Eating Lake Erie Sport Fish

Fish Number of Meals Suggested Yellow Perch No Restrictions Walleye One Meal a week Freshwater drum Carp under 20” One meal a month White perch Steelhead Trout Coho salmon Chinook salmon over 19” Smallmouth bass White bass Carp over 20” One meal every two months Carp from Maumee Bay Channel catfish Lake Trout Channel catfish DO NOT EAT From Maumee Bay

g. Looking at this chart, give a possible explanation for why carp and channel catfish from Maumee bay must contain the highest level of contaminants?

h. Give two other reasons why some fish are safer to eat than other fish.

g. What effect do you think the natural life span of a fish might have on its PCB content (hint: salmon live 4-6 years while lake trout live 15-20 years). Which would you suspect to have more PCBs?