BSCS Packet #2 – Ecology, part 1 (Unit 2) 2013-2014

This Activity Packet belongs to: ___________________ (___Block)Complete this packet as we go through the activities, notes, the case study, and labs. You will not turn this packet in, but you should expect a variety of quizzes: pop-mini-quizzes (HW credit) on recent work, lab quizzes (lab/ activity credit), and regular quizzes.

5E Page # Activity Due Date

Elaborate Separate packet Ecology Reading Guide

Engage 2-5 Journal 2-1: Interactions in the World Around Us

Explore 6-7 Community Ecology Notes

Explain 8 Ecology Bumper Sticker Mini-Project

9-34 Journal 2-2: The Fish Kill Mystery (Case study with embedded lab)

Engage 9-16 Case Study, Day 1

Explain 16-21 Case Study, Day 2

Engage 22-24 Lab 2-1: pH Lab Procedures A & B, Day 3

Explore 24-28 Lab 2-1: pH Lab Procedures C, Day 4

Explain 29-31 Protist notes & Lab 2-2: Microscope Introduction, Day 5

Explore 32-33 Case Study, Day 6

Explore 34 Lab 2-2: Exploring Pond Life, Day 7

Explore 35-40 Journal 2-3: Mystery on Easter Island

Elaborate 41-47 Easter’s End article (homework)

Evaluate 48 Ecology Vocab & Ecology Packet 1 Review (for quiz/test)

If this packet is LOST, please:drop it off at the BHS Science Dept. (rm 365) ORdrop it off in MS. JUO’S classroom (rm 347) OR

call the Science Dept. at (617) 713-5365.

Daphnia

Journal 2-1: Interactions in the World Around Us (from p 623-625 of BSCS: A Human Approach)

Introduction: Why might an ecologist study a certain area? There are a variety of reasons. Say you were an ecologist studying a particular area. You would attempt to describe and understand the interrelationships that exist between organisms and their environment. First, you would gather information about the organisms and their environment. Then, you might compare this area to different regions to look for similarities, differences, and patterns. Finally, you would try to explain the patterns you observed. You might run experiments to test your hypotheses.

In this activity, you will practice thinking like an ecologist. You will look for patterns and explanations for the interactions you observed in the engage activity. You also will have the opportunity to compare your observations with a series of DVD images from around the world that represent a wide variety of interactions in many different settings.

Procedure:

1. Use your own words to write a definition for the term ecosystem.

2. Take notes on following topics (Intro to Ecology ppt):Ecology

Ecological Levels

Abiotic vs Biotic Factors

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Examples:

3. Watch the DVD segment “Images from around the world.” Pay particular attention to the interactions that involve humans and provide examples of the influences assigned on your task cards. Record at least three examples in the table below:

Negative effect of humans on the abiotic environment

Positive effect of humans on the abiotic environment

Negative effect of humans on other organisms

Positive effect of humans on other organisms

Negative effect of humans on other humans

Positive effect of humans on other humans

Effect of nonhuman organisms on other organisms

Effect of nonhuman organisms on the abiotic environment

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4. Discuss your DVD observations with your partner. Prepare to show your examples with the rest of the class.

5. Participate in a class discussion about the video and your observations. Take notes.

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pg625 from BSCS: A Human Approach

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Analysis:

1. Read the scenario Early Morning Reflections on page 625 of your textbook. Think about the interactivity examples from that reading and the images in the DVD. Write one or two logical conclusions that you can make from those examples about the interactions taking place in the world.

2. The term biosphere refers to the portion of the earth where organisms naturally live. It begins in the lower atmosphere and extends deep into the earth’s crust. Do you think that humans have more or less influence on the biosphere than other organisms? Explain your response.

3. Do you think that humans have a responsibility to monitor how they influence the biosphere? Explain your response.

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BSCS Notes – Community EcologyBefore we begin, define community (from Journal 2-1 notes):

Habitat vs. niche

Describe the habitat and niche for the following organisms:

Sea Star

Habitat-Niche: Nutrition- Activity- Reproduction- Locomotion-

Spider

Habitat-Niche: Nutrition- Activity- Reproduction- Locomotion-

Gray squirrel

Habitat-Niche: Nutrition- Activity- Reproduction- Locomotion-

InteractionsInterspecies competition happens when…

Examples:

(+, -, or 0)

___/___

Predation

Examples:

(+, -, or 0)

___/___

Protection against predationCamouflage:

Mimicry:

What is symbiosis?Page 7

What are the 3 types of symbiosis?

What is mutualism?

Examples:

(+, -, or 0)

___/___

What is commensalism?

Examples:

(+, -, or 0)

___/___

What is parasitism?

Examples:

(+, -, or 0)

___/___

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Ecology Bumper Sticker Mini-Project

This project will give you an opportunity to be creative, both in thought and design. Bumper stickers are eye-catchers, and in that vein, you will design an eye-catching bumper sticker about one ecology-related word that will be assigned to you.

Your design should be on a piece of paper that is 11 ½ inches long and about 4 inches wide. Take a piece of blank computer paper and fold it in half lengthwise:

As mentioned, be creative – use color, drawings, and a clever saying that defines your word. Remember, bumper stickers are usually brief – maybe a sentence – so give yourself plenty of time to think of a clever saying.

An example:If I was assigned the word biology, I could say: ”Biology: Got Life?” I could then draw diagrams of living things around the edge.

You can find information about your word from your textbook, class notes, and online resources. Define your word before you begin to plan the layout of your bumper sticker.

Rubric: 10 pts max Excellent Fine needs helpFormat: plain paper, horizontal fold

1 – followed directions 0.5 – partly followed directions

0 – ignored directions

Word is clearly displayed on the bumper sticker

1 – the word is obvious and used well

0.5 – the word may be there but not obvious

0 – the word is not there

Phrase or slogan convey correct meaning clearly

3 – phrase/slogan gives meaning of the word

2 – phrase/slogan there, but reader is not sure of meaning incorrect

1 – incorrect meaning or confusing or no phrase/slogan

Hand-drawn, colorful picture OR picture pasted from another source that is properly cited on the front of the bumper sticker (MLA format)

2 – followed directions, nicely draw, a good layout of pictures

1 – if hand-drawn, not colorful OR picture from other source is not properly cited

0 – no picture or a poor picture

Neat and well-planned 1 – well laid out 0.5 – thrown together 0 - sloppyCreativity 2 – very creative 1 – somewhat creative 0 – textbook

definition

Possible Vocab –:ProducerFirst order consumerSecond order consumerDecomposersPyramid of biomassPyramid of numbersPyramid of energyFood chain

Food webEcological successionMatter cyclesEnergy flowsBiotic factorsAbiotic factorsPopulationCommunity

EcosystemPredatorPreySymbiosisCarrying CapacityLimiting FactorNiche

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The Fish Kill MysteryNATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCEBy Erica F. Kosal, Biology Department, North Carolina Wesleyan College

with additions from BSCS, A Human Approach, modified by J. Juo

Day 1 - The ScenarioIt was a hot North Carolina July morning and Susan and her friends were headed to the beach. Everyone had the day off from work and it seemed a wonderful opportunity to cool down and have a good time. Susan figured she could get to the beach in two hours from her house in Rocky Mount. After putting on her swimsuit and grabbing her sunscreen, she got into the car. Twenty minutes later she had picked up Kathy and Linda and they were off to the coast!After driving over a bridge that crossed the Pamlico Estuary, a strong odor began to permeate the car. Kathy covered her nose with her hand. Linda, who hadn’t eaten breakfast, felt her stomach turn over and thought to herself that the day was going to be spoiled. Susan, however, was curious and suggested they explore.“What do you think that smell is, anyway?” she said as she pulled the car over and jumped out, leaving her friends no choice but to follow her.As they got closer to the estuary, the source of the odor became clear when they saw hundreds of dead fish floating on the water and washed up on the beach. When Kathy caught up to Susan and Linda, she gasped, “I’ve never seen such a sight—how horrible!”A group of people was gathered on the shore. Some were pulling dead fish out of the estuary while others were sampling the water using various pieces of equipment. The three women walked over and learned that the group was made up of volunteers who were working to clean up the area as well as several biologists gathering data. Kathy, Susan, and Linda offered to help.

Temperature and Dissolved OxygenSusan was working with one of the biologists, Dr. Edwin Trout, and his graduate student from the local university. She liked Dr. Trout. He appeared focused on his work, but was friendly at the same time. His graduate student, Mark Cooper, was also nice and seemed very passionate about collecting data. Susan directed her questions to him: “What caused this fish kill? Was it the heat? It seems to be affecting a lot of animals these days.”“Well, the high temperatures are often related to low oxygen levels in the water,” Mark replied. “Come on over here. I’ll show you some data maps we have been collecting from the Neuse River.”Mark showed Susan a series of dissolved oxygen maps (http://www.esb.enr.state.nc.us/NeuFolder/images/060708do.gif), pointing out to her that the colors on the maps indicated different concentrations of oxygen.“The blue colors indicate high amounts of oxygen (in mg/L) and so these

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areas are good for the fish,” Mark explained. “The red colors indicate areas in the river where dissolved oxygen is low, around to mg/L. Here is where fish would have a problem. Typically, dissolved oxygen, or , readings of mg/L or less are harmful to fish.”Studying the map for August (http://www.sciencecases.org/fishkill/doaug2002.avi), Susan saw changes occurring over the month. She noticed that at times the river seemed to house enough dissolved oxygen for the fish, but at other times, for example, on August st and August th, red areas were found, indicating that dissolved oxygen was very low in these sections of the river.“Wow, I didn’t realize the dissolved oxygen could fluctuate so much over a short period of time,” said Susan.“What is the here today?” Kathy was working with another small group of people nearby, but became more interested in the conversation between Mark and Susan.Mark responded, “The reading here right now is mg/L. It may have been down to at some point, but I don’t think so.”

“How did the fish die then?” Susan was really interested now. But Kathy interrupted her. “Hey, wait,” she said. “Before you answer that, Mark, you never explained how temperature and dissolved oxygen are connected.”“Oh, you’re right. I’m sorry,” Mark replied. “The amount of oxygen that water can hold depends a lot on its temperature. The cooler the water, the more oxygen it can hold and the warmer the water, the less oxygen it can hold. Look at the map for December of . Notice how much more dissolved oxygen the water holds. Almost everyday there is blue indicated or dissolved oxygen readings in the to mg/L range. Think about how this compares to the maps of August you just looked at, where it was unusual to see blue colors.”

Questions:1. What is the relationship between temperature and dissolved oxygen?

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2. Based on the evidence from the reading, do you think that a lack of oxygen killed the fish? Explain your reasoning.

Split up the following pages of background reading among your group members:1. Algae & cyanobacteria 2. Daphnia & Gammarus3. Pesticides 4. Acid rain

For tonight’s HW:Read your section of background reading and write down any information that may give your group a better understanding of factors that could have led to the death of the fish. You will present your information to your group.

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Algae and CyanobacteriaMost bodies of fresh water on the earth contain microscopic organisms called algae and cyanobacteria (blue-green bacteria). These organisms exist in a variety of forms and colors and are a major food source for aquatic organisms.

Preferred EnvironmentAlgae and cyanobacteria grow anywhere there is a body of water or sufficient quantity of moisture. Submersed glass, shells, and rotting wood all are surfaces on which algae can attach and grow. It also is common to find algae and bacteria growing under the rims of dams or on the edges of stones. Algae and cyanobacteria can grow in threadlike strands or form a fuzzy film. In humid climates, some types grow on the trunks of trees, the surfaces of leaves, or even the backs of shelled animals, such as turtles and crabs. Each type of alga is adapted to its environment in a different way. For example, a type of single-celled alga that contains a red pigment grows on permanent snowfields, giving the snow a reddish color.

Types of Algae and CyanobacteriaThe most commonly found types of algae are green algae, golden algae, and diatoms. Green algae are grass-green in color and can live as single cells, in colonies (groups), or as strands of attached cells called filaments. Many of the single-celled and colonial forms move by means of two to eight threadlike structures called flagella. The golden algae are golden yellow in color and live as single cells or in colonies. Many move by means of two flagella of unequal length. Diatoms are generally brownish in color and can live as single cells or in colonies. They have hard shells that have a top and a bottom like a box and move by gliding. Cyanobacteria are bluish green in color and can live as single cells, in colonies, or in filaments. Some of them move by gliding.

Ecological RelationshipsWhen a lake first forms, it often has few nutrients and supports only a small plant community. Scientists refer to this stage of a lake as being unproductive. When a lake has an abundance of nutrients, it is referred to as productive. Sometimes lakes age from the unproductive stage to the productive stage due to drainage from industrial and residential areas that deposits high concentrations of nitrates and phosphates in the water.Nitrates and phosphates are important nutrients that normally are present in low concentrations. When concentrations increase due to pollution, cyanobacteria and algae may have population explosions. The massive populations of these organisms give the water a pea-green color and produce a funny smell. As the populations increase, many of the algae and cyanobacteria die off. Oxygen-using decomposer bacteria then increase in numbers, which drops the oxygen levels in the lake. As a result, many fish die, which upsets the lake’s balance*. Algae and cyanobacteria are some of the best indicators that a lake is productive.

*This process is called eutrophication.

Information from Copymasters, BSCS – A Human Approach

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DaphniaDaphnia are small aquatic animals. Sometimes called water fleas, they are about 1 millimeter (less than 1/16 inch) long. They move by making rapid strokes with their two feathery antennae. Their clear outer shells make it easy to observe their internal structures, including the beating heart. The heartbeat of a Daphnia varies with the temperature of the water.

Preferred EnvironmentDaphnia thrive in an aquatic environment with a temperature around 20°C (68°F). Higher temperatures usually are fatal, but lower temperatures do not affect them adversely. Daphnia eggs can survive up to eight thaws and freezes; this thaw/freeze cycle stimulates hatching.Daphnia orient themselves by focusing on light that is coming from one direction; they have difficulty swimming when they are exposed to equal amounts of light coming toward them from all directions.

Feeding HabitsDaphnia feed on a variety of organisms, such as bacteria, algae, and protoctists (microscopic, single-celled organisms). Daphnia eat by moving their legs to produce small water currents that sweep the organisms into their mouths. Their feeding rate depends on food concentration, food quality, water temperature, light intensity, oxygen concentration, pH levels, and crowding. Large concentrations of Daphnia can process immense amounts of algae at a time. When food is scarce, Daphnia may outcompete other small organisms, causing these organisms to die.

ReproductionDaphnia produce eggs that develop without fertilization. An adult female may carry 10 to 15 eggs, which develop and hatch in a special brood pouch under its shell. These eggs hatch as female offspring. Adverse conditions, such as excessive crowding, increased water temperature, decreased food supply, or environmental change such as the drying up of a pond, trigger the production of males and females that reproduce sexually. These sexual Daphnia produce eggs in the fall that survive through winter and hatch the next spring.

Ecological RelationshipsDaphnia are a principal food staple for fish and thus are an important link in the food chain. Fish stomachs may contain 95 percent Daphnia by volume. Daphnia also help maintain water quality by efficiently cleaning up cyanobacteria blooms in lakes. These blooms are caused by an overabundance of inorganic nutrients such as phosphates. Phosphates are found in a variety of household cleaning products, and they can leach into water-ways through runoff. Because Daphnia can reduce the amount of algae and cyanobacteria by half in a small amount of time, they are important to lake restoration programs.

Information from Copymasters, BSCS – A Human Approach

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GammarusGammarus are small crustaceans from the order Amphipoda, which means “feet around.” Nicknamed “scuds,” Gammarus have a unique habit of swimming on their sides and are well known for their acrobatic behavior. Fossil records indicate that crustaceans such as Gammarus have existed since the early Paleozoic period.

Preferred EnvironmentGammarus are one of the few types of freshwater crustaceans that have adapted to marine coastal and cave environments that have a mix of saltwater and freshwater. They are bottom dwellers, usually living on the floors of lakes, rivers, and streams that are well oxygenated, clean, and cool in temperature. Gammarus can reach densities of more than 1,000 individuals per square meter when food is abundant and there is protection from predators. They are sensitive to bright light and have specialized receptors that help them to detect even slight differences in light intensities.

Feeding HabitsGammarus have a well-developed chemical sensory system that enables them to identify potential food and mates by scent. Juveniles normally feed on algae and bacteria that are attached to aquatic plants. Adults and juveniles alike consume dead organic matter, which provides protein.

ReproductionMating occurs soon after the female sheds her shell (molts), when she is vulnerable and needs a male’s protection. During this time, she exposes her eggs for fertilization and waits for her new shell to harden. She then holds her larvae in a birthing chamber called the marsupium. Normally, females produce only one brood during their 1- to 11⁄2-year lifetime. The type of Gammarus most common to the United States needs short days and long nights to reproduce. Therefore, reproduction usually takes place during the winter.

Ecological RelationshipsGammarus are sensitive to changes in their environment, and changes such as acidification of the water can threaten their survival. Because Gammarus are a main source of food for larger freshwater organisms, observations of the effects of pollution on Gammarus can indicate how pollution affects freshwater environments as a whole.

Information from Copymasters, BSCS – A Human Approach

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PesticidesHumans have used pesticides since the time of the ancient Greeks, who used common compounds such as sulfur and olive oil to combat unwanted pests. Unfortunately, by the 19th and 20th centuries, these safe, organic methods were traded for compounds made of heavy metals. The mid-20th century brought creations such as DDT and toxaphene, which later were found to be highly carcinogenic. For a long time, no one seemed to question the use of pesticides. Farmers and government officials fighting the ongoing battle with weeds, insects, plant diseases, and other animals viewed pesticides as a welcome solution.

Many people think that pesticides affect only the land to which they are applied, but pesticides can be spread by water. Water flows through the world like a web. Each river, stream, lake, and ocean is somehow connected. Thus, water runoff from farms and residential areas can affect waterways in adverse ways. It is hard to track exact locations of agricultural water pollution because much of the pollution reaches lakes through groundwater contamination. Half of all water pollution comes from nonpoint sources, which means that the point of pollution cannot be identified.

A fish kill in a Minnesota lake provides an example of the adverse effects of pesticides. In 1989, a fisherman informed a reporter that he had witnessed a major bluegill kill on Coon Lake due to herbicide contamination of the water. (A herbicide is a type of pesticide that destroys plants.) As the man was fishing, a weed-control vessel passed the nearby shoreline and, as it left, the fish began to suffocate. Although the herbicide was intended only to control aquatic weeds along the shoreline, it was toxic enough to kill the fish.

When a lake is contaminated, it is often impossible to restock it with fish because the toxins remain potent even after they have settled into lake sediments. Small organisms such as plankton ingest tiny amounts of toxins into their bodies, and in turn, are eaten by larger predator fish. These fish, through time, absorb chemicals through their gills. With each link in the food chain, this process of accumulation increases the concentration of toxic chemicals. High concentrations of toxic chemicals result in the deaths of large predator fish.**

Although the United States government has banned many pesticides and herbicides, traces of them still can be found in the environment. Newer pesticides that are supposed to be less of a risk to the environment may be harmful to bees, insects, and many fish species. In the summer of 1991, for example, an estimated 750,000 fish died as the result of pesticide runoff from sugar cane fields in Louisiana.

** This process is called biomagnification

Information from Copymasters, BSCS – A Human Approach

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Acid PrecipitationWhat do you think of when you hear the words acid rain? Do you picture green water that melts everything it touches? Do you think of brown, battery-acid raindrops that sting your skin and singe your hair? Acid rain does not look dangerous, and it feels like normal rain: wet, cool, and good for the garden. However, the effects of acid rain can help turn water green, erode rock or metal, and harm nature.

Acid rain results when rain reacts with acidic molecules and particles in the air. These acidic molecules and particles get into the air as emissions—from industry, automobiles, volcanoes, and sulfur-releasing processes—and linger in the atmosphere until it rains. Acid rain lowers the pH level of lakes. A low pH indicates that the water is significantly acidic. Acid rain affects the environment and organisms in a variety of ways, including the following. It

◆erodes stone and cement; ◆causes chemical damage to metal surfaces; ◆changes the chemistry of soil and water; ◆inhibits bacterial growth; ◆decreases plant growth; ◆causes lesions in plants; and ◆affects the reproduction, development, growth, and survival of organisms.

Lakes are perfect models for observing the effects of acid rain. In the United States, acid rain has acidified many lakes in Minnesota, Wisconsin, and upper Michigan, including the Great Lakes. Acid rain also has affected much of the mountainous areas of the West and Southwest. Fortunately, the rate of acidification seems to be slower than was predicted 10 years ago.

In acidified lakes, acid rain has taken its toll on fish and aquatic organisms, mainly damaging species that were valued for sport fishing. Low pH levels have eliminated many fish species and phytoplankton species. And acid rain is just one of many ailments that lakes face. A combination of acid rain and toxic waste pollution can make a lake appear unsalvageable, but many communities are trying to restore their lakes. Declining sulphur emissions have allowed for some recovery of freshwater lakes in the United States and Canada, but it is not clear whether lakes will be able to recover completely. Studies have shown, however, that when pH levels of a lake are raised, it is possible to reintroduce eliminated species.

Information from Copymasters, BSCS – A Human Approach

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3. For HW, record any information about your assigned background reading that may give your group a better understanding of factors that could have led to the death of the fish. In class, you will complete the table below by taking notes as your group members present their finding.

Algae and Cyanobacteria Daphnia & Gammarus

Pesticides Acid Rain

Day 2 – Examining the PossibilitiesA. Present your background information to your group, take notes in the table provided above, and answer Questions 4 and 5 below.

4. What other information do you need to know before you can determine which is most likely to have killed the fish?

5. List all of the abiotic and biotic factors in a lake from our work so far and describe interactions between these factors.

B. Lakes are local ecosystems in which scientists can study populations of fish. The following data provides information about populations of largemouth bass and yellow perch. Examine the information and graphs below, then answer the questions that follow.

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Information from Copymasters, BSCS – A Human Approach

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Information from Copymasters, BSCS – A Human Approach

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Graph 1: This graph shows the number of fish caught each fishing season in the Tri-Lakes region between 1982 and 2002.

Graph 2. This bar graph shows the number of bass (black bar) and the number of perch (gray bar) caught each fishing season between 1982 and 2002 in the Tri-Lakes region.

Information from Copymasters, BSCS – A Human Approach

Questions continued: Interpreting data from long-term studies6. Based on Graph 1, what is the pattern for the total number of fish caught in the last 5 years compared to previous years?

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Graph 3. This graph shows the average size of bass (black bar) and perch (gray bar) caught in the Tri-Lakes region during the 1982-2002 fishing seasons.

7. Based on Graph 2, what pattern or trend do you see for bass? For perch?

8. Based on Graph 3, what pattern or trend do you see for bass? For perch?

9. What is missing from Graph 3? (If you left this out you’d lose points!)

10. Taking all three graphs into consideration: a. Which fish (bass or perch) seems to have been more sensitive to changes in the lake ecosystem? Refer to specific graphs when explaining your answer.

b. Why is it important to examine ALL three graphs when trying to understand the ecosystem of the lake?

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Examining the Effects of pH More Closely:

How Does Acid Rain Affect Fish and Other Aquatic Organisms?http://www.epa.gov/acidrain/effects/surface_water.htmlAcid rain causes a cascade of effects that harm or kill individual fish, reduce fish population numbers, completely eliminate fish species from a water body, and decrease biodiversity. As acid rain flows through soils in a watershed, aluminum is released from soils into the lakes and streams located in that watershed. So, as pH in a lake or stream decreases, aluminum levels increase. Both low pH and increased aluminum levels are directly toxic to fish. In addition, low pH and increased aluminum levels cause chronic stress that may not kill individual fish, but leads to lower body weight and smaller size and makes fish less able to compete for food and habitat.

Some types of plants and animals are able to tolerate acidic waters. Others, however, are acid-sensitive and will be lost as the pH declines. Generally, the young of most species are more sensitive to environmental conditions than adults. At pH 5, most fish eggs cannot hatch. At lower pH levels, some adult fish die. Some acid lakes have no fish. The chart below shows that not all fish, shellfish, or the insects that they eat can tolerate the same amount of acid; for example, frogs can tolerate water that is more acidic (i.e., has a lower pH) than trout.

Table 1: pH Tolerance of Various Organisms. pH 6.5 pH 6.0 pH 5.5 pH 5.0 pH 4.5 pH 4.0

Trout Yes Yes Yes Yes No NoBass Yes Yes Yes No No NoPerch Yes Yes Yes Yes Yes NoFrogs Yes Yes Yes Yes Yes YesSalamanders Yes Yes Yes Yes No NoClams Yes Yes No No No NoCrayfish Yes Yes Yes No No NoSnails Yes Yes No No No NoMayfly Yes Yes Yes No No No

Questions continued:11. What other abiotic factor is known to be toxic to fish other than low pH?

12. Which organism is least tolerant to low pH level?

13. Of the three fish (trout, bass, and perch), which can best tolerate a lower pH level?

For tonight’s HW: Read the pH Lab and highlight important information. Answer Questions

1-3 after reading the Introduction and Background section.Page 25

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Day 3 – Understanding the Basics of pHDuring this block, you will conduct a pH lab to practice testing pH (using pH paper) and demonstrate how living things use buffers to maintain homeostasis. You will learn about what pH is and how to read a pH scale. This is “Procedure A: Practice measuring pH with pH paper” and “Procedure B: pH and homeostasis” from your Ecology Packet.

You will be assigned your group’s organism: Daphnia or Gammarus.

Lab 2-1: Fish Kill Mystery pH LabOriginal from W. Sailer, with additions from BSCS – a Human Approach, modified by J. Juo

Introduction and Background Reading:

In this lab you will learn what acids and bases are and how they are measured on the pH scale using pH paper. You will test a few samples, then test the capacity of a living system to buffer against pH changes – evidence for homeostasis.

Many substances are classified according to the chemical quality of being acidic or basic. To measure this quality, scientists use the pH scale. The pH scale measures how acidic a solution is. The scale ranges from 0 to 14, and the meaning of these values is the opposite of what you might expect. The lower the pH value, the stronger the acid is. A solution with a pH of less than 7 is classified as an acid. The higher the pH value, the weaker the acid is. A solution with a pH above 7 is low in acidity and is classified as a base. So, while the pH scale measures acidity, it also measures how basic a solution is.

A pH value of 7 - the midpoint of the scale - indicates a neutral solution. A neutral solution is neither acidic nor basic. Each consecutive number on the pH scale represents a tenfold change in acidity or basicity. For example, a solution with a pH of 5 is 10 times more acidic than a solution with a pH of 6.

In water solutions, whether a solution is acidic or basic depends on the relative concentration of hydrogen ions (H+) and hydroxide ions (OH-). Acidic water solutions have more H+ ions than OH- ions. Basic water solutions have more OH- ions than H+ ions. Pure water, which is neutral, contains equal numbers of H+ ions and OH- ions:

H+ + OH- = H2O Hydrogen ion hydroxide ion water

Acids add H+ ions to water solutions. For example, hydrochloric acid (HCl), which is a strong acid, separates into H+ ions and Cl- ions in water. This raises the number or H+ ions in the solution. Bases combine with H+ ions in water solutions. For example, sodium hydroxide (NaOH), which is a strong base, separates into Na+ and OH- in water. The OH- ions combine with H+ ions in the water. This lowers the number or H+ ions in the solution.

The pH of a solution is tested with special dyes. These dyes change color as the acidity in the solution changes. The dyes are usually put on a strip of paper called pH paper. The pH paper is keyed to a color chart, which shows the color that the paper will be at different pH values.

Many biological reactions require specific pH ranges in order to function properly. The pH of solutions inside and outside of cells greatly influences chemical processes. Digestive enzymes in the mouth work best at a pH of 6.8, and those in the stomach work best at a pH of 2. Stomach enzymes do not work at a pH of 9. The functions of blood require a nearly neutral pH, not varying much from pH 7.2 to 7.4. In fact, each cell, tissue, and organ has a characteristic pH that is important for homeostasis.

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Often, however, organisms are exposed to things that have a pH that is very different from their own. For example, much of the food that you eat has a pH that is different from that of your stomach. How do living tsystems maintain a relatively stable pH in their internal environment when changes occur in their external environment?

A buffer maintains the pH of a solution within a narrow range of values even when external conditions threaten to change pH. In effect, this means that small additions of acid or base to a buffered solution do not cause a change in pH. Cells have physiological buffers that help maintain its characteristic pH; this protects the internal environment. Different types of buffers are effective in maintaining pH within different ranges. One type of buffer might keep the internal pH in a slightly acidic range, and a different type might keep the pH of the inside of another cell in a neutral range.

After reading the Introduction and Background section, answer the following questions in your own words:1. What is pH?

2. How much more acidic is a solution with a pH of 5 compared to a solution with a pH of 7?

3. What is homeostasis?

Materials: Spot plate, color chart and pH paper, 0.1 M hydrochloric acid (HCl), 0.1 M sodium hydroxide (NaOH).

Your samples for today may include a few of the following:baking soda in water, carbonated beverage, crushed raw potato in water, lemon or tomato juice, egg white, water, your saliva

Procedure A: Practice measuring pH with pH paperCaution! Hydrochloric acid and sodium hydroxide are strong chemicals that can burn skin and clothing. Handle them with care.

Put a few drops of each solution to be tested on a spot plate. Make sure you use the numbers on the plate so that you know which solution is in which spot! You will need one strip per sample. Avoid touching the paper with your hands. Match the color of the pH paper to the color chart to determine the pH of the solution. Discard the used pH paper, and record your pH data on the data table. Repeat this procedure for each solution, using a new piece of pH paper every time.

Data Table 1: Predicting and Measuring pH of Samples. Number on Spot Plate

Name of Sample Predicted pH number Actual pH number from pH paper

1 0.1M HCl2 0.1M NaOH3456

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Procedure B: pH and homeostasis

Data Table 2: Systematically Decreasing the Acidity of a Liquid. As NaOH (base) is added to water:Number of total drops added

pH of water pH of buffer solution pH of milk

Individual data Class data Individual

data Class data Individual data Class data

05101520

Results: Organizing DataGraph 1: Construct a line graph to illustrate collected data in regards to pH.Be sure that your line graph includes a descriptive title, labeled x-axis, labeled y-axis, and a key to show which data correspond to water, etc.

For tonight’s HW: Finish graphing your pH data and write a conclusion for the pH lab. Read the following in your Ecology Packet “Procedure C: The Effect of pH on

Microorganisms, Daphnia and Gammarus”. Follow the directions to complete your pre-lab, which includes writing a formal hypothesis based on the question, and setting up a data table to record your group data.

Day 4 – Understanding How pH Affects OrganismsDuring this block, you will perform an experiment to test how pH affects Daphnia and Gammarus, two organisms that live in freshwater. You will record both your group’s data as well as copy down class data.

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Procedure C: The Effect of pH on Microorganisms, Daphnia and Gammarus.

Overview: In this lab you will work in groups to answer the question ‘how does pH affect the microorganisms Daphnia and Gammarus?’ Each group of 2-3 students will be assigned one microorganism (Daphnia or Gammarus). If you alter the given protocol in any way, make sure that you make note of it. When you have collected all your data, have one person in your group record the data in the class chart while the rest of the group cleans up their lab space.

Pre-Lab: Read through the entire lab, write a hypothesis for your experiment, and create a data table (see next page).

Hypothesis:

Materials: room temperature aquarium H2O (~22oC), 2 small (ex. 50mL) beakers, graduated cylinders to measure volume of H2O (25 mls), vinegar in dropper bottle, distilled H2O in dropper bottle, pH paper, disposable plastic pipette, Q-tip or toothpick for stirring, hand lens, “used culture” beakers (control, variable), labeling tape, sharpie marker.

Cooperative Group Roles for the D and G lab Fill in name of group member

Communicator (with other groups, the teacher) – remember ‘Ask 3 before me!’Keeper of materials (gathers and returns),Data manager (records group & class data)Lab manager (ensures group members focuses on tasks, and each member has copied group & class data by end of the session)

Procedure: Remember that pH measures how acidic a liquid is. pH values range from 0-14; 0 is the most acidic and 14 is the least acidic.

Your group’s organism: _________________

1. Add 25 mL of room temperature water to the “experimental” beaker.2. Using plastic pipette, place 2 Daphnia or Gammarus in the beaker. Use hand lens to

observe organism behavior and record in chart.3. Measure and record the pH of vinegar by adding one drop of vinegar to the pH paper _____.4. Measure and record the pH of the water in chart with “Trial 1”.5. Adding 1 drop at a time and stirring gently in between each drop with a Q-tip or toothpick,

add 3 drops of acid (vinegar) to the beaker.6. Measure pH. pH should change slightly. If the pH does not change, add one drop of acid at

a time (stirring in between) until it does change slightly. Keep track of how many drops you added!

7. Once the pH changes, record the pH of the water and total # of vinegar drops added under “Trial 2”.

8. Use hand lens to observe organism behavior and record in chart. Repeat steps 5-8.9. As a control set up, repeat steps above in a second beaker. However, use distilled water

instead of acid, being careful to add the same number of drops as you did in the experimental group for each trial.

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Your Group’s Data Table:Use a ruler to draw your table.Remember to account for:

two groups (control and experimental groups) 5 trials quantitative data (pH measurements, number of drops) qualitative data (observations of behavior – you can also be as quantitative as you can

here, ex. Gammarus swam up to the surface 3 times in one minute).

Cleanup reminder: All “control” organisms should be placed in the appropriate waste beaker labeled “control Daphnia” or “control Gammarus”. All “variable” organisms should be placed in the waste beaker labeled “variable”. Please wash all of the lab equipment (anything that touched aquarium water or organisms, such as beakers) with soapy water, rinse well, and turn them upside down on a paper towel on your tray to dry. Your trays should look exactly as they did when you received them.

Don’t forget to send one person (the data manager) up to fill in the class data chart. Each person needs to copy the class data in the chart provided for use in completing the Analysis Q’s.

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The Effect of pH on Microorganisms, Daphnia and Gammarus.Class Data – Summary of Observed Patterns

Lab Group #

OrganismDaphnia or

Gammarus?

pH range Behavior observations

1

2

3

4

5

For tonight’s HW:Page 32

Answer Discussion Questions for the Daphnia and Gammarus lab and complete the Pre-lab section of Lab 2-2 (Microscopes) using your textbook.

Discussion: Analysis Questions:1. For the experiment that your group performed, describe the control set-up. Be specific. Why is having a control set-up so important? In other words, your results would be invalid without the control – explain why.

2. What pattern appears from your group’s data with the microorganism in your experiment? OR, what are some of the inconsistencies in your group’s data? (In other words, what pattern did you expect that is NOT apparent?)

3. Use the class data to tell the similarities and differences between the two microorganisms and their responses to pH.

4. Based on the class data, do you think that acid rain is a potential cause for the death of the fish in the Fish Kill Case Study?

Conclusion: What can you conclude about pH, homeostasis, and living systems from this lab? (3-5 sentences)

Day 5 – Microorganisms in Freshwater EcosystemsPage 33

During this block, you will learn about how to use a microscope and about protists (an important part of water ecosystems). On Day 7, you will use a microscope to examine pond life.

Previewing Protists – Notes from the powerpoint presentation:What is the Endosymbiont Theory?

When we organize, or classify, organisms, we put them first into 3 Domains (Archaea, Bacteria, and Eukarya) and within these Domains are subcategories called Kingdoms. The Eukarya Kingdom consists of Protista, Fungi, Plantae, and Animalia. Why is the Protista Kingdom the most diverse kingdom of all?

List the characteristics of Protists:

What are examples of animal-like protists and what are some of their important characteristics?

What are examples of plant-like protists and what are some of their important characteristics?

What are examples of fungi-like protists?

Lab 2-2: Fish Kill Mystery (Exploring Pond Life)

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Adapted from Prentice-Hall.

Introduction: Ecosystems are collections of living and non-living things. In this lab you will be examining a pond ecosystem. You will be taking close observations of the organisms that live in this ecosystem, specifically to compare and learn about various protists. This will also be your chance to review or learn about the proper use of the microscope.

Pre-Lab: Complete the table below using your textbook Appendix

Part Name FunctionABCDEFGHIJ

Procedure Part I – Learning About the Microscope

1. One member of your lab group should obtain a microscope. Always carry the microscope in an upright position (not tilted) using two hands. One hand should hold the microscope’s arm and the other hand should support the base, as shown in Figure 1. Set it down away from the edge of the table. Always remember that a microscope is an expensive, precision instrument that should be handled carefully. Do not push the microscope around on the table, but instead swivel the ocular lens or reposition your body.

2. Plug the microscope in at your lab desk. Turn it on and make sure

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Word Bank:

ArmBaseCoarse AdjustmentDiaphragmFine AdjustmentObjective Lenses (high & low powers)Eyepiece/ Ocular LensLight/ IlluminatorStageStage Clips

that the light comes on.

3. Compare your microscope with the diagram on the previous page. Identify the parts on your microscope and determine the function of each part. Use the words from the word bank to fill in the parts names in Table 1.

4. The ocular lens is marked with its magnification power. (This is how much larger the lens makes objects appear.) What is the magnification power of the ocular lens of your microscope? _____________

5. The three objective lenses are marked with their magnification power. The first number marked on each lens is the magnification power of that lens.

a. What is the magnification of the lowest power lens of your microscope? _______b. What is the magnification of the high power lens? _______

6. To find the total magnification of the microscope as you are using it, multiply the ocular lens power times the power of the objective lens that you are using. For example, if the ocular lens of a microscope has a power of 5x and you use an objective that is 10x, then the total magnification of the microscope at that time is 50x (5x10 = 50).

a. What is the total magnification of your microscope when using low power? ____What is the total magnification of your microscope when using high power? ____

THE LETTER “e” (Practice)1. From the newspaper, find a lower case letter “e.”2. Cut out the letter.3. Place it on a slide (so that it is upright). Place 1-2 drops of water over the letter.4. Lower a cover slide. Use a 45-degree angle to minimize air bubbles.5. Start with lowest power, and then move up to medium power.6. Using 100X total magnification, sketch everything that you see (not what you THINK you should

see). Use pencil, and include as much detail as possible. Don’t forget to label your diagram with the total magnification used.

Total Magnification: ____ X

Sketch of how the “e” looks on the stage without using the microscope:

For tonight’s HW: Read the Day 6 reading (a separate, small packet) – we continue with the Scenario. Do

NOT answer questions at home, you will do this in class.

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Answer these IN CLASS with your group

– DO NOT DO THESE FOR HOMEWORK – POINTS OFF!

Questions for Day 6 reading (separate packet):.14. Why are estuaries, such as the Pamlico Estuary, so important?

15. What is killing the fish? Explain specifically what, how, and why this happens.

16. High levels of nutrients moving into the estuary have been linked to Pfiesteria outbreaks. What nutrient sources might contribute to this problem? You should be able to list several potential nutrient sources.

17. What are the potential impacts of the toxin on human health?

18. The Environmental Protection Agency (EPA) has regulations to manage water pollution. (You may examine those found at http://www.epa.gov/lawsregs/laws/cwa.html). Given that nutrient influx can be considered a form of pollution, do you think additional regulation is needed? Why or why not?

19. Under which circumstances should we try to control the population numbers of Pfiesteria? a. If human health was not threatened, but commercially valuable fish species were harmed, should we control Pfiesteria? Justify your answer.

b. If the fish species harmed were not commercially significant, should we control Pfiesteria? Justify your answer.

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20. HONOR ONLY: Briefly summarize the two different camps of thought on the life cycle of Pfiesteria. Given there is an active controversy in the scientific community on the Pfiesteria life stages, should public policy decisions be made when the scientific community is not in agreement? Take these two questions into consideration: What would happen if action on this problem were delayed until the controversy was resolved? What if action were taken without all the “facts” known?

For tonight’s HW:Read 20-1 “The Kingdom Protista” in the Dragonfly textbook and answer the Section Assessment Q’s on p498. 1. What is a protist?

2. Describe Margulis’s theory about the evolution of protists.

3. Are most protists unicellular or multicellular?

4. What are the three methods that protists use to obtain food?

5. Identify the characteristics of organisms belonging to the kingdom Protista.

6. Critical Thinking/ Using Analogies: In what way is the kingdom Protista similar to a group of people who do not belong to a political party?

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Day 7 – Microorganisms in Freshwater Ecosystems under a Microscope

Procedure Part II – Exploring Pond Life1. All data should be recorded in the provided data table. Make detailed observations. You

should always draw your own sketches – it is considered plagiarism to copy off of someone else’s sketch!

2. Make one depression slide of the pond water culture for your pair. a. Using a pipette, gently transfer 1-3 drops from the jar to the depression slide.b. You may add a few strands of cotton fiber from cotton balls. This may slow down

the organisms while you are observing them.3. Examine the slide under the microscope, first under low power, then under medium

power. a. You should always start in low power because this makes it easiest to find the

objects on the slide. Position the diaphragm so that the largest opening is used, allowing the maximum amount of light through.

b. While looking through the ocular lens, use the coarse adjustment knob to bring the sample into focus. Then use the fine adjustment knob to sharpen the focus.

c. Important Note: Before switching to the next higher power, you should always position the specimen in the center of the field of view and use the fine adjustment to focus the image. DO NOT move the stage back down before switching objectives. Never use the coarse adjustment when using medium or high power.

d. Switch to the medium power objective lens and use the fine adjustment knob to sharpen the focus. It should already be mostly in focus from your previous viewing.

4. Search for and find one organism on the slide. Use the “Pond Life” books to identify the organisms you might observe in your pond water culture. Record the type of organism that you have found and do a sketch of the organism in the data table. Also record any significant facts that you learn from the “Pond Life” book.

5. Leave your microscope focused on the organism and the “Pond Life” book open to the appropriate page at your lab bench.

6. Once you have completed the observation of your organism visit 2 other microscopes and repeat Step #5 above.

7. Obtain a freshly-prepared depression slide of protists (ex. paramecium, spirogyra, amoeba, dinoflagellates) from your teacher. Observe the dinoflagellates using the microscope under low power, then medium power. Determine which power is best to use for observations. Record observations & power used and sketch the organism on the separate paper provided.

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Journal 2-3: Mystery on Easter Island (P 627-632 of BSCS: A Human Approach)

Part I: Read the introduction on page 627 of the BSCS Textbook and do the “Process and Procedures” as described below. Note that you will not do #3 as written in the textbook. Refer to the Notes sheet provided.

Process and Procedures:1. Study the graph on page 629 and answer the questions. Don’t forget units (like people,

years people/year, etc)!

a. _____________________ f. _____________________

b. _____________________ g. _____________________

c. _____________________ h. _____________________

d. _____________________ i. _____________________

e. _____________________ j. _____________________

2. Refer to the vegetation charts and information in Figure 15.8. Write a brief description of the Easter Island ecosystem. Include at least 3 examples of biotic and 3 examples of abiotic resources that likely influenced the colonizing population.

3. Read the Easter Island Notes Sheet (next page).

4. Looking back at Figure 15.8 and the Easter Island Notes Sheet, discuss with your partner the changes that took place on Easter Island after colonization. Below, write 1 or 2 paragraphs that summarize the changes in vegetation on Easter Island between 950 and 1980. Explain what you think caused those changes.

Analysis: (From Page 631-632)Look at the essay “Interdependence Involves Limiting Factors and Carrying Capacity” on page 650 as a resource to answer the following questions.1. Think about the growth in human population between 1000 and 1600. Compare that with the

rate of growth during the first years that colonizers were on the island (450 to 1000). What might account for this large increase in the rate of growth?

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2. Easter Island Notes Sheet

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3. p650 from BSCS: A Human Approach

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4. p651 from BSCS: A Human Approach

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5. p652 from BSCS: A Human Approach

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6. What factor or factors finally limited the growth of the human population?

What other factors might limit the growth of a population? Give at least three specific examples.

7. Redraw the population growth graph in Figure 15.7. Color-code your graph so that each significant trend in the rate of growth is a different color. Create a legend that shows what type of growth rate happened during each different-colored period.

8. The maximum number of people that the island can support without destroying its ability to renew itself is called its carrying capacity. Add a line to your graph that shows where you think the island’s carrying capacity for people was when the colonizers first landed on Easter Island. Label this line initial carrying capacity. Why did you draw your line there? (Think – did the people reach carrying capacity? Did they exceed it?)

9. What evidence is there that the number of people on the island exceeded carrying capacity?

10.Add another line to your graph. Show where you think the island’s carrying capacity for people was after 1690. Label this line later carrying capacity. Why did you draw your line there?

11.What does this study tell you about unchecked population growth?

12.Think about the relationship between the island’s population size and resources-available-per-individual. What does this relationship demonstrate?

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Easter's End by Jared Diamond, Discover Magazine 08.01.1995

Among the most riveting mysteries of human history are those posed by vanished civilizations. Everyone who has seen the abandoned buildings of the Khmer, the Maya, or the Anasazi is immediately moved to ask the same question: Why did the societies that erected those structures disappear?

Their vanishing touches us as the disappearance of other animals, even the dinosaurs, never can. No matter how exotic those lost civilizations seem, their framers were humans like us. Who is to say we won’t succumb to the same fate? Perhaps someday New York’s skyscrapers will stand derelict and overgrown with vegetation, like the temples at Angkor Wat and Tikal.

Among all such vanished civilizations, that of the former Polynesian society on Easter Island remains unsurpassed in mystery and isolation. The mystery stems especially from the island’s gigantic stone statues and its impoverished landscape, but it is enhanced by our associations with the specific people involved: Polynesians represent for us the ultimate in exotic romance, the background for many a child’s, and an adult’s, vision of paradise. My own interest in Easter was kindled over 30 years ago when I read Thor Heyerdahl’s fabulous accounts of his Kon-Tiki voyage.

But my interest has been revived recently by a much more exciting account, one not of heroic voyages but of painstaking research and analysis. My friend David Steadman, a paleontologist, has been working with a number of other researchers who are carrying out the first systematic excavations on Easter intended to identify the animals and plants that once lived there. Their work is contributing to a new interpretation of the island’s history that makes it a tale not only of wonder but of warning as well.

Easter Island, with an area of only 64 square miles, is the world’s most isolated scrap of habitable land. It lies in the Pacific Ocean more than 2,000 miles west of the nearest continent (South America), 1,400 miles from even the nearest habitable island (Pitcairn). Its subtropical location and latitude--at 27 degrees south, it is approximately as far below the equator as Houston is north of it--help give it a rather mild climate, while its volcanic origins make its soil fertile. In theory, this combination of blessings should have made Easter a miniature paradise, remote from problems that beset the rest of the world.

The island derives its name from its discovery by the Dutch explorer Jacob Roggeveen, on Easter (April 5) in 1722. Roggeveen’s first impression was not of a paradise but of a wasteland: We originally, from a further distance, have considered the said Easter Island as sandy; the reason for that is this, that we counted as sand the withered grass, hay, or other scorched and burnt vegetation, because its wasted appearance could give no other impression than of a singular poverty and barrenness.

The island Roggeveen saw was a grassland without a single tree or bush over ten feet high. Modern botanists have identified only 47 species of higher plants native to Easter, most of them grasses, sedges, and ferns. The list includes just two species of small trees and two of woody shrubs. With such flora, the islanders Roggeveen encountered had no source of real firewood to warm themselves during Easter’s cool, wet, windy winters. Their native animals included nothing larger than insects, not even a single species of native bat, land bird, land snail, or lizard. For domestic animals, they had only chickens.

European visitors throughout the eighteenth and early nineteenth centuries estimated Easter’s human population at about 2,000, a modest number considering the island’s fertility. As Captain James Cook recognized during his brief visit in 1774, the islanders were Polynesians (a Tahitian man accompanying Cook was able to converse with them). Yet despite the Polynesians’ well-deserved fame as a great seafaring people, the Easter Islanders who came out to Roggeveen’s and Cook’s ships did so by swimming or paddling canoes that Roggeveen described as bad and frail. Their craft, he wrote, were put together with manifold small planks and light inner timbers, which they cleverly stitched together with very fine twisted threads. . . . But as they lack the knowledge and particularly the materials for caulking and making tight the great number of seams of the canoes, these are accordingly very leaky, for which reason they are compelled to spend half the time in bailing. The canoes, only ten feet long, held at most

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two people, and only three or four canoes were observed on the entire island.

With such flimsy craft, Polynesians could never have colonized Easter from even the nearest island, nor could they have traveled far offshore to fish. The islanders Roggeveen met were totally isolated, unaware that other people existed. Investigators in all the years since his visit have discovered no trace of the islanders’ having any outside contacts: not a single Easter Island rock or product has turned up elsewhere, nor has anything been found on the island that could have been brought by anyone other than the original settlers or the Europeans. Yet the people living on Easter claimed memories of visiting the uninhabited Sala y Gomez reef 260 miles away, far beyond the range of the leaky canoes seen by Roggeveen. How did the islanders’ ancestors reach that reef from Easter, or reach Easter from anywhere else?

Easter Island’s most famous feature is its huge stone statues, more than 200 of which once stood on massive stone platforms lining the coast. At least 700 more, in all stages of completion, were abandoned in quarries or on ancient roads between the quarries and the coast, as if the carvers and moving crews had thrown down their tools and walked off the job. Most of the erected statues were carved in a single quarry and then somehow transported as far as six miles--despite heights as great as 33 feet and weights up to 82 tons. The abandoned statues, meanwhile, were as much as 65 feet tall and weighed up to 270 tons. The stone platforms were equally gigantic: up to 500 feet long and 10 feet high, with facing slabs weighing up to 10 tons.

Roggeveen himself quickly recognized the problem the statues posed: The stone images at first caused us to be struck with astonishment, he wrote, because we could not comprehend how it was possible that these people, who are devoid of heavy thick timber for making any machines, as well as strong ropes, nevertheless had been able to erect such images. Roggeveen might have added that the islanders had no wheels, no draft animals, and no source of power except their own muscles. How did they transport the giant statues for miles, even before erecting them? To deepen the mystery, the statues were still standing in 1770, but by 1864 all of them had been pulled down, by the islanders themselves. Why then did they carve them in the first place? And why did they stop?

The statues imply a society very different from the one Roggeveen saw in 1722. Their sheer number and size suggest a population much larger than 2,000 people. What became of everyone? Furthermore, that society must have been highly organized. Easter’s resources were scattered across the island: the best stone for the statues was quarried at Rano Raraku near Easter’s northeast end; red stone, used for large crowns adorning some of the statues, was quarried at Puna Pau, inland in the southwest; stone carving tools came mostly from Aroi in the northwest. Meanwhile, the best farmland lay in the south and east, and the best fishing grounds on the north and west coasts. Extracting and redistributing all those goods required complex political organization. What happened to that organization, and how could it ever have arisen in such a barren landscape?

Easter Island’s mysteries have spawned volumes of speculation for more than two and a half centuries. Many Europeans were incredulous that Polynesians--commonly characterized as mere savages--could have created the statues or the beautifully constructed stone platforms. In the 1950s, Heyerdahl argued that Polynesia must have been settled by advanced societies of American Indians, who in turn must have received civilization across the Atlantic from more advanced societies of the Old World. Heyerdahl’s raft voyages aimed to prove the feasibility of such prehistoric transoceanic contacts. In the 1960s the Swiss writer Erich von Däniken, an ardent believer in Earth visits by extraterrestrial astronauts, went further, claiming that Easter’s statues were the work of intelligent beings who owned ultramodern tools, became stranded on Easter, and were finally rescued.

Heyerdahl and Von Däniken both brushed aside overwhelming evidence that the Easter Islanders were typical Polynesians derived from Asia rather than from the Americas and that their culture (including their statues) grew out of Polynesian culture. Their language was Polynesian, as Cook had already concluded. Specifically, they spoke an eastern Polynesian dialect related to Hawaiian and Marquesan, a

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dialect isolated since about A.D. 400, as estimated from slight differences in vocabulary. Their fishhooks and stone adzes resembled early Marquesan models. Last year DNA extracted from 12 Easter Island skeletons was also shown to be Polynesian. The islanders grew bananas, taro, sweet potatoes, sugarcane, and paper mulberry--typical Polynesian crops, mostly of Southeast Asian origin. Their sole domestic animal, the chicken, was also typically Polynesian and ultimately Asian, as were the rats that arrived as stowaways in the canoes of the first settlers.

What happened to those settlers? The fanciful theories of the past must give way to evidence gathered by hardworking practitioners in three fields: archeology, pollen analysis, and paleontology.

Modern archeological excavations on Easter have continued since Heyerdahl’s 1955 expedition. The earliest radiocarbon dates associated with human activities are around A.D. 400 to 700, in reasonable agreement with the approximate settlement date of 400 estimated by linguists. The period of statue construction peaked around 1200 to 1500, with few if any statues erected thereafter. Densities of archeological sites suggest a large population; an estimate of 7,000 people is widely quoted by archeologists, but other estimates range up to 20,000, which does not seem implausible for an island of Easter’s area and fertility.

Archeologists have also enlisted surviving islanders in experiments aimed at figuring out how the statues might have been carved and erected. Twenty people, using only stone chisels, could have carved even the largest completed statue within a year. Given enough timber and fiber for making ropes, teams of at most a few hundred people could have loaded the statues onto wooden sleds, dragged them over lubricated wooden tracks or rollers, and used logs as levers to maneuver them into a standing position. Rope could have been made from the fiber of a small native tree, related to the linden, called the hauhau. However, that tree is now extremely scarce on Easter, and hauling one statue would have required hundreds of yards of rope. Did Easter’s now barren landscape once support the necessary trees?

That question can be answered by the technique of pollen analysis, which involves boring out a column of sediment from a swamp or pond, with the most recent deposits at the top and relatively more ancient deposits at the bottom. The absolute age of each layer can be dated by radiocarbon methods. Then begins the hard work: examining tens of thousands of pollen grains under a microscope, counting them, and identifying the plant species that produced each one by comparing the grains with modern pollen from known plant species. For Easter Island, the bleary-eyed scientists who performed that task were John Flenley, now at Massey University in New Zealand, and Sarah King of the University of Hull in England.

Flenley and King’s heroic efforts were rewarded by the striking new picture that emerged of Easter’s prehistoric landscape. For at least 30,000 years before human arrival and during the early years of Polynesian settlement, Easter was not a wasteland at all. Instead, a subtropical forest of trees and woody bushes towered over a ground layer of shrubs, herbs, ferns, and grasses. In the forest grew tree daisies, the rope- yielding hauhau tree, and the toromiro tree, which furnishes a dense, mesquite-like firewood. The most common tree in the forest was a species of palm now absent on Easter but formerly so abundant that the bottom strata of the sediment column were packed with its pollen. The Easter Island palm was closely related to the still-surviving Chilean wine palm, which grows up to 82 feet tall and 6 feet in diameter. The tall, unbranched trunks of the Easter Island palm would have been ideal for transporting and erecting statues and constructing large canoes. The palm would also have been a valuable food source, since its Chilean relative yields edible nuts as well as sap from which Chileans make sugar, syrup, honey, and wine.

What did the first settlers of Easter Island eat when they were not glutting themselves on the local equivalent of maple syrup? Recent excavations by David Steadman, of the New York State Museum at Albany, have yielded a picture of Easter’s original animal world as surprising as Flenley and King’s picture of its plant world. Steadman’s expectations for Easter were conditioned by his experiences

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elsewhere in Polynesia, where fish are overwhelmingly the main food at archeological sites, typically accounting for more than 90 percent of the bones in ancient Polynesian garbage heaps. Easter, though, is too cool for the coral reefs beloved by fish, and its cliff-girded coastline permits shallow-water fishing in only a few places. Less than a quarter of the bones in its early garbage heaps (from the period 900 to 1300) belonged to fish; instead, nearly one-third of all bones came from porpoises.

Nowhere else in Polynesia do porpoises account for even 1 percent of discarded food bones. But most other Polynesian islands offered animal food in the form of birds and mammals, such as New Zealand’s now extinct giant moas and Hawaii’s now extinct flightless geese. Most other islanders also had domestic pigs and dogs. On Easter, porpoises would have been the largest animal available--other than humans. The porpoise species identified at Easter, the common dolphin, weighs up to 165 pounds. It generally lives out at sea, so it could not have been hunted by line fishing or spearfishing from shore. Instead, it must have been harpooned far offshore, in big seaworthy canoes built from the extinct palm tree.

In addition to porpoise meat, Steadman found, the early Polynesian settlers were feasting on seabirds. For those birds, Easter’s remoteness and lack of predators made it an ideal haven as a breeding site, at least until humans arrived. Among the prodigious numbers of seabirds that bred on Easter were albatross, boobies, frigate birds, fulmars, petrels, prions, shearwaters, storm petrels, terns, and tropic birds. With at least 25 nesting species, Easter was the richest seabird breeding site in Polynesia and probably in the whole Pacific.

Land birds as well went into early Easter Island cooking pots. Steadman identified bones of at least six species, including barn owls, herons, parrots, and rail. Bird stew would have been seasoned with meat from large numbers of rats, which the Polynesian colonists inadvertently brought with them; Easter Island is the sole known Polynesian island where rat bones outnumber fish bones at archeological sites. (In case you’re squeamish and consider rats inedible, I still recall recipes for creamed laboratory rat that my British biologist friends used to supplement their diet during their years of wartime food rationing.)

Porpoises, seabirds, land birds, and rats did not complete the list of meat sources formerly available on Easter. A few bones hint at the possibility of breeding seal colonies as well. All these delicacies were cooked in ovens fired by wood from the island’s forests.

Such evidence lets us imagine the island onto which Easter’s first Polynesian colonists stepped ashore some 1,600 years ago, after a long canoe voyage from eastern Polynesia. They found themselves in a pristine paradise. What then happened to it? The pollen grains and the bones yield a grim answer.

Pollen records show that destruction of Easter’s forests was well under way by the year 800, just a few centuries after the start of human settlement. Then charcoal from wood fires came to fill the sediment cores, while pollen of palms and other trees and woody shrubs decreased or disappeared, and pollen of the grasses that replaced the forest became more abundant. Not long after 1400 the palm finally became extinct, not only as a result of being chopped down but also because the now ubiquitous rats prevented its regeneration: of the dozens of preserved palm nuts discovered in caves on Easter, all had been chewed by rats and could no longer germinate. While the hauhau tree did not become extinct in Polynesian times, its numbers declined drastically until there weren’t enough left to make ropes from. By the time Heyerdahl visited Easter, only a single, nearly dead toromiro tree remained on the island, and even that lone survivor has now disappeared. (Fortunately, the toromiro still grows in botanical gardens elsewhere.)

The fifteenth century marked the end not only for Easter’s palm but for the forest itself. Its doom had been approaching as people cleared land to plant gardens; as they felled trees to build canoes, to transport and erect statues, and to burn; as rats devoured seeds; and probably as the native birds died out that had pollinated the trees’ flowers and dispersed their fruit. The overall picture is among the most extreme examples of forest destruction anywhere in the world: the whole forest gone, and most of its tree species extinct.

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The destruction of the island’s animals was as extreme as that of the forest: without exception, every species of native land bird became extinct. Even shellfish were overexploited, until people had to settle for small sea snails instead of larger cowries. Porpoise bones disappeared abruptly from garbage heaps around 1500; no one could harpoon porpoises anymore, since the trees used for constructing the big seagoing canoes no longer existed. The colonies of more than half of the seabird species breeding on Easter or on its offshore islets were wiped out.

In place of these meat supplies, the Easter Islanders intensified their production of chickens, which had been only an occasional food item. They also turned to the largest remaining meat source available: humans, whose bones became common in late Easter Island garbage heaps. Oral traditions of the islanders are rife with cannibalism; the most inflammatory taunt that could be snarled at an enemy was The flesh of your mother sticks between my teeth. With no wood available to cook these new goodies, the islanders resorted to sugarcane scraps, grass, and sedges to fuel their fires.

All these strands of evidence can be wound into a coherent narrative of a society’s decline and fall. The first Polynesian colonists found themselves on an island with fertile soil, abundant food, bountiful building materials, ample lebensraum, and all the prerequisites for comfortable living. They prospered and multiplied.

After a few centuries, they began erecting stone statues on platforms, like the ones their Polynesian forebears had carved. With passing years, the statues and platforms became larger and larger, and the statues began sporting ten-ton red crowns--probably in an escalating spiral of one-upmanship, as rival clans tried to surpass each other with shows of wealth and power. (In the same way, successive Egyptian pharaohs built ever-larger pyramids. Today Hollywood movie moguls near my home in Los Angeles are displaying their wealth and power by building ever more ostentatious mansions. Tycoon Marvin Davis topped previous moguls with plans for a 50,000-square-foot house, so now Aaron Spelling has topped Davis with a 56,000-square-foot house. All that those buildings lack to make the message explicit are ten-ton red crowns.) On Easter, as in modern America, society was held together by a complex political system to redistribute locally available resources and to integrate the economies of different areas.

Eventually Easter’s growing population was cutting the forest more rapidly than the forest was regenerating. The people used the land for gardens and the wood for fuel, canoes, and houses--and, of course, for lugging statues. As forest disappeared, the islanders ran out of timber and rope to transport and erect their statues. Life became more uncomfortable-- springs and streams dried up, and wood was no longer available for fires.

People also found it harder to fill their stomachs, as land birds, large sea snails, and many seabirds disappeared. Because timber for building seagoing canoes vanished, fish catches declined and porpoises disappeared from the table. Crop yields also declined, since deforestation allowed the soil to be eroded by rain and wind, dried by the sun, and its nutrients to be leeched from it. Intensified chicken production and cannibalism replaced only part of all those lost foods. Preserved statuettes with sunken cheeks and visible ribs suggest that people were starving.

With the disappearance of food surpluses, Easter Island could no longer feed the chiefs, bureaucrats, and priests who had kept a complex society running. Surviving islanders described to early European visitors how local chaos replaced centralized government and a warrior class took over from the hereditary chiefs. The stone points of spears and daggers, made by the warriors during their heyday in the 1600s and 1700s, still litter the ground of Easter today. By around 1700, the population began to crash toward between one-quarter and one-tenth of its former number. People took to living in caves for protection against their enemies. Around 1770 rival clans started to topple each other’s statues, breaking the heads off. By 1864 the last statue had been thrown down and desecrated.

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As we try to imagine the decline of Easter’s civilization, we ask ourselves, Why didn’t they look around, realize what they were doing, and stop before it was too late? What were they thinking when they cut down the last palm tree?

I suspect, though, that the disaster happened not with a bang but with a whimper. After all, there are those hundreds of abandoned statues to consider. The forest the islanders depended on for rollers and rope didn’t simply disappear one day--it vanished slowly, over decades. Perhaps war interrupted the moving teams; perhaps by the time the carvers had finished their work, the last rope snapped. In the meantime, any islander who tried to warn about the dangers of progressive deforestation would have been overridden by vested interests of carvers, bureaucrats, and chiefs, whose jobs depended on continued deforestation. Our Pacific Northwest loggers are only the latest in a long line of loggers to cry, Jobs over trees! The changes in forest cover from year to year would have been hard to detect: yes, this year we cleared those woods over there, but trees are starting to grow back again on this abandoned garden site here. Only older people, recollecting their childhoods decades earlier, could have recognized a difference. Their children could no more have comprehended their parents’ tales than my eight-year-old sons today can comprehend my wife’s and my tales of what Los Angeles was like 30 years ago.

Gradually trees became fewer, smaller, and less important. By the time the last fruit-bearing adult palm tree was cut, palms had long since ceased to be of economic significance. That left only smaller and smaller palm saplings to clear each year, along with other bushes and treelets. No one would have noticed the felling of the last small palm.

By now the meaning of Easter Island for us should be chillingly obvious. Easter Island is Earth writ small. Today, again, a rising population confronts shrinking resources. We too have no emigration valve, because all human societies are linked by international transport, and we can no more escape into space than the Easter Islanders could flee into the ocean. If we continue to follow our present course, we shall have exhausted the world’s major fisheries, tropical rain forests, fossil fuels, and much of our soil by the time my sons reach my current age.

Every day newspapers report details of famished countries-- Afghanistan, Liberia, Rwanda, Sierra Leone, Somalia, the former Yugoslavia, Zaire--where soldiers have appropriated the wealth or where central government is yielding to local gangs of thugs. With the risk of nuclear war receding, the threat of our ending with a bang no longer has a chance of galvanizing us to halt our course. Our risk now is of winding down, slowly, in a whimper. Corrective action is blocked by vested interests, by well-intentioned political and business leaders, and by their electorates, all of whom are perfectly correct in not noticing big changes from year to year. Instead, each year there are just somewhat more people, and somewhat fewer resources, on Earth.

It would be easy to close our eyes or to give up in despair. If mere thousands of Easter Islanders with only stone tools and their own muscle power sufficed to destroy their society, how can billions of people with metal tools and machine power fail to do worse? But there is one crucial difference. The Easter Islanders had no books and no histories of other doomed societies. Unlike the Easter Islanders, we have histories of the past--information that can save us. My main hope for my sons’ generation is that we may now choose to learn from the fates of societies like Easter’s.

Easter’s End Questions:Page 51

1. The author asks “Did Easter’s now barren landscape once support the necessary trees?” What methods did scientists use to answer that question – what did they conclude?

2. The author asks “What did the first settlers of Easter Island eat when they were not glutting themselves on the local equivalent of maple syrup?” Briefly state the answer here.

3. List (in bullet points) what the evidence tells us destroyed the “pristine paradise” of Easter Island.

4. How does Easter Island’s situation compare to Earth’s problems today?

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BSCS – “Ecology” Exam Study Guide (Part 1)

Vocabulary – some of these terms will be introduced to you in the next packet (Ecology Part 2), you may wish to check off words from this packet as we come across them.

Here are some vocabulary words, which you should understand and be able to apply. This list is for your own reference - do NOT turn anything in regarding this list! It might be beneficial to you to make flashcards or to use this list to ask someone to quiz you on the meanings. But, don’t turn it in to me – do it as a studying method.Ecology Population Community EcosystemBiome Food web Consumers (primary, etc.) ProducersDecomposers Trophic level Herbivore CarnivoreOmnivore Pyramid of biomass Biotic Abiotic Limiting factor Carrying capacity Population density EutrophicationGrowth rate Doubling time Mortality NatalityImmigration Emigration Predation (predator/prey) CompetitionNiche Habitat Symbiosis MutualismParasitism Commensalism Ecological succession BioticAbiotic Pyramid of Numbers Pyramid of Energy Food chainWater cycle Carbon cycle Nitrogen cycle Pioneer plantNitrogen fixation Photosynthesis Cellular respiration TranspirationExponential (J-shaped) growth Logistic (S-shaped) growth Density-dependent limiting factors Density-independent limiting factorsClimax community Succession (primary vs. secondary, land vs. aquatic)

Study Questions – due date: _________________The answers to these questions can be found in the readings, in your notes and answers to questions from labs and activities. Either write the question into your answer OR download this from msjuo.weebly.com and type your answers in the document. 1. Draw a diagram showing the relationship among: population, community, ecosystem.2.Compare and contrast the various interspecific interactions within a community (e.g. predator/prey,

symbiotic, competition).3.List all possible causes for a decrease in a fish population in an estuary or lake.4.What is pH? Draw the pH scale and label: acidic, basic, neutral.5.Why is acid rain important to consider when trying to understand the well-being of organisms in a

freshwater ecosystem?6.What is dissolved oxygen? How is it important to the well-being of an aquatic ecosystem? What is

eutrophication and how does it affect the oxygen content of an aquatic ecosystem? 7.What are characteristics of protists?8.If you are looking at a specimen using the 40X objective lens: what is the total magnification? which

adjustment knob must you NOT use? Know the parts and functions of a microscope and be able to use a diagram of the microscope.

9. What factors affected the carrying capacity of Easter Island for the human population?10. How might climate (temperature, rainfall, wind, etc.), light, disease, food availability, and space limit

the size of a population? Label each of these as density-dependent or density-independent.11. What causes logistic growth rather than exponential growth?12. Given the growth rate of two populations, be able to calculate and compare doubling time. If the

growth rate for population A is 0.5% and for population B is 4%, what is the doubling time for each? How do they compare? (hint: see your notes on doubling time)

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