BSCS Packet #2 – Ecology, part 1 (Unit 2)
2014-2015
This Activity Packet belongs to: ___________________ (___Block)
Complete this packet as we go through the activities, notes, the case study, and labs. You hould expect
a variety of quizzes: pop-mini-quizzes (HW credit) on recent work, lab quizzes, and regular quizzes.
5E
Page #
Activity
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)
Reading Guide
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) OR
drop it off in MS. SIFANTUS’S classroom (rm 345) OR
call the Science Dept. at (617) 713-5365.
Daphnia
Due
Date
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
Examples:
Page 2
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
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.
Page 3
pg625 from BSCS: A Human Approach
Page 4
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.
Page 5
BSCS Notes – Community Ecology
Before we begin, define community (from Journal 2-1 notes):
Habitat vs. niche
Describe the habitat and niche for the following organisms:
HabitatNiche:
 Nutrition Activity ReproductionSea Star
 LocomotionHabitatNiche:
 Nutrition Activity ReproductionSpider
 LocomotionHabitatNiche:
 Nutrition Activity ReproductionGray squirrel
 LocomotionInteractions
Interspecies competition happens when…
(+, -, or 0)
___/___
Examples:
Predation
(+, -, or 0)
___/___
Examples:
Protection against predation
Camouflage:
Mimicry:
Page 6
What is symbiosis?
What are the 3 types of symbiosis?
What is mutualism?
(+, -, or 0)
___/___
Examples:
What is commensalism?
(+, -, or 0)
___/___
Examples:
What is parasitism?
(+, -, or 0)
___/___
Examples:
Page 7
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 help
Format: plain paper,
horizontal fold
Word is clearly
displayed on the
bumper sticker
Phrase or slogan
convey correct meaning
clearly
1 – followed directions
0.5 – partly followed
directions
0.5 – the word may be
there but not obvious
0 – ignored
directions
0 – the word is not
there
3 – phrase/slogan gives
meaning of the word
2 – phrase/slogan there,
but reader is not sure of
meaning incorrect
Hand-drawn, colorful
picture OR picture
pasted from another
source that is properly
cited on the front of the
bumper sticker (MLA
format)
Neat and well-planned
Creativity
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
1 – incorrect
meaning or
confusing or no
phrase/slogan
0 – no picture or a
poor picture
1 – well laid out
2 – very creative
0.5 – thrown together
1 – somewhat creative
Possible Vocab –:
Producer
First order consumer
Second order consumer
Decomposers
Pyramid of biomass
Pyramid of numbers
Pyramid of energy
Food chain
1 – the word is obvious
and used well
Food web
Ecological succession
Matter cycles
Energy flows
Biotic factors
Abiotic factors
Population
Community
0 - sloppy
0 – textbook
definition
Ecosystem
Predator
Prey
Symbiosis
Carrying Capacity
Limiting Factor
Niche
Page 8
The Fish Kill Mystery
NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE
By Erica F. Kosal, Biology Department, North Carolina Wesleyan College
with additions from BSCS, A Human Approach, modified by J. Juo
Day 1 - The Scenario
It 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 Oxygen
Susan 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 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,
mg/L or less are harmful to fish.”
Studying the map for August
Page 9
(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.
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
some point, but I don’t think so.”
at
“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?
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 & Gammarus
Page 10
3. 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.
Page 11
Algae and Cyanobacteria
Most 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 Environment
Algae 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 Cyanobacteria
The 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 Relationships
When 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
Page 12
Daphnia
Daphnia 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 Environment
Daphnia 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 Habits
Daphnia feed on a variety of organisms, such as bacteria, algae, and protoctists (microscopic, singlecelled 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.
Reproduction
Daphnia 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 Relationships
Daphnia 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
Page 13
Gammarus
Gammarus 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 Environment
Gammarus 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 Habits
Gammarus 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.
Reproduction
Mating 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 Relationships
Gammarus 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
Page 14
Pesticides
Humans 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
Page 15
Acid Precipitation
What 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
Page 16
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 Possibilities
A. 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.
Page 17
Information from Copymasters, BSCS – A Human Approach
Page 18
Information from Copymasters, BSCS – A Human Approach
Page 19
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.
Page 20
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.
Information from Copymasters, BSCS – A Human Approach
Questions continued: Interpreting data from long-term studies
6. Based on Graph 1, what is the pattern for the total number of fish caught in the last 5 years
compared to previous years?
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?
Page 21
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.html
Acid 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
Trout
Yes
Yes
Yes
Bass
Yes
Yes
Yes
Perch
Yes
Yes
Yes
Frogs
Yes
Yes
Yes
Salamanders
Yes
Yes
Yes
Clams
Yes
Yes
No
Crayfish
Yes
Yes
Yes
Snails
Yes
Yes
No
Mayfly
Yes
Yes
Yes
pH 5.0
Yes
No
Yes
Yes
Yes
No
No
No
No
pH 4.5
No
No
Yes
Yes
No
No
No
No
No
pH 4.0
No
No
No
Yes
No
No
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 22
Day 3 – Understanding the Basics of pH
During 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 Lab
Original 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. Homeostasis is the
Page 23
internal stability that organisms must maintain in order to support life. For example, organisms must
maintain certain levels of pH, body temperature, and blood sugar levels.
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 systems 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? Use terms such as ‘an acidic solution”, a ‘basic solution’, and a neutral solution. Describe
which has more H+ ions.
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 paper
Caution! 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.
See Data Table on next page
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Data Table 1: Predicting and Measuring pH of Samples.
Number
Name of Sample
Predicted pH number
on Spot
Plate
1
0.1M HCl
2
0.1M NaOH
3
4
5
6
Actual pH number
from pH paper
Procedure B: pH and homeostasis
1. Measure 10 ml of water into a small beaker.
2. Use pH paper to measure the pH before any drops of base are added. Record the pH.
3. Add NaOH 5 drops at a time. STIR after you add the drops. Measure and record the pH.
4. Continue to add NaOH 5 drops at a time, stirring and recording the pH each time.
Data Table 2: Systematically Decreasing the Acidity of a Liquid.
As NaOH (base) is added to water:
Number
pH of water
pH of buffer solution
of total
Individual
Individual
drops
Class data
Class data
data
data
added
0
5
10
15
20
pH of milk
Individual
data
Class data
Results: Organizing Data
Graph 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.
Page 25
For tonight’s HW:
 Finish graphing your pH data. Write one sentence describing what the data ‘says’ and onetwo sentences inferring what it means. These are meant to be WELL WRITTEN and
CONCISE sentences. Describe 3 sources of error- only one source can be a human
error. Describe how each S/E affected or may have affected the data.
 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 Organisms
During 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.
Page 27
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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Lab
Group #
The Effect of pH on Microorganisms, Daphnia and Gammarus.
Class Data – Summary of Observed Patterns
Organism
pH range
Behavior observations
Daphnia or
Gammarus?
1
2
3
4
5
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For tonight’s HW:
 Answer Discussion Questions for the Daphnia and Gammarus lab and complete the Prelab 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)
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Day 5 – Microorganisms in Freshwater Ecosystems
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?
Page 31
Lab 2-2: Fish Kill Mystery (Exploring Pond Life)
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
Word Bank:
Arm
Base
Coarse Adjustment
Diaphragm
Fine Adjustment
Objective Lenses (high & low powers)
Eyepiece/ Ocular Lens
Light/ Illuminator
Stage
Stage Clips
Part
A
B
C
D
E
F
G
H
I
J
Name
Function
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.
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2. Plug the microscope in at your lab desk. Turn it on and make sure 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.
Page 34
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?
Page 35
Day 7 – Microorganisms in Freshwater Ecosystems under a Microscope
Procedure Part II – Exploring Pond Life
1. 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.
Page 36
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?
p650 from BSCS: A Human Approach
p 651 from BSCS: A Human Approach
Page 37
2. p652 from BSCS: A Human Approach
Page 38
3. 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.
4. 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.
5. 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?)
6. What evidence is there that the number of people on the island exceeded carrying capacity?
7. 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?
8. What does this study tell you about unchecked population growth?
9. Think about the relationship between the island’s population size and resources-availableper-individual. What does this relationship demonstrate?
Page 39
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
Page 40
reason they are compelled to spend half the time in bailing. The canoes, only ten feet long, held at most
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
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concluded. Specifically, they spoke an eastern Polynesian dialect related to Hawaiian and Marquesan, a
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
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picture of its plant world. Steadman’s expectations for Easter were conditioned by his experiences
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
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species extinct.
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-yearold 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.
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Easter’s End Questions:
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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READING GUIDE: This reading guide is meant to help you take notes on specific sections of the textbook that will be
assigned for homework. You are expected to read the pages for each assignment, and to fill in the missing information on the
given outlines below. Not all of the bolded words in the book appear below: often you will need to use these words as you
explain the topics given below. Your notes should be written in your own words, showing that you understand the reading
assignment and are not merely copying text from the book. Please be sure to look at the figures in the book in each section,
especially using ones identified in the outline below.
I. What is Ecology? (3.1, p62)
A. Studying the biosphereB. EcologyC. Levels of organization (make a diagram like Figure 3-2, defining species, population, community, ecosystem,
biome, and biosphere)
D. Ecological Methods
1. Observing
2. Experimenting
3. Modeling
II. What Shapes an Ecosystem? (4.2: p. 90)
A. Biotic and Abiotic features of an ecosystem (define and give examples)
1. Biotic2. AbioticB. HabitatC. Niche (explain how niche differs from habitat)-
1. resourcesa. examples of resources:
2. biotic and physical aspects of a nicheD. Competition in communities-
E. Predation, Herbivory, and Keystone Species
1. Predator-Prey relationships2. Herbivore (plant-eating) and Producer (plant) relationships3. Keystone species (explain sea otter example as a keystone species)-
E. Symbioses (Symbiotic relationships)
1. Symbiosis2. Different types of symbioses (explain with an example for each)
a. mutualism-
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b. commensalismc. parasitismIII. Populations in Ecosystems and their Growth (5.1: p. 118)
A. Studying populations
1. Geographic Range2. Density and Distribution3. Growth Rate4. Age StructureB. Factors that affect population growth
1. birth rate2. death rate3. immigration4. emigrationC. Types of population Growth
1. Exponential Growth
a. shape of growth curve (sketch, using Fig. 5-3)
b. examples of organisms with exponential growth-
c. conditions that lead to exponential growth-
2. Logistic Growth
a. phases of growth (describe phases 1-3)
b. shape of growth curve (sketch, using Fig. 5-4)
c. conditions that lead to logistic growth-
d. carrying capacity-
IV. Limits in Population Growth (5.2: p.124)
A. Limiting factorsB. Examples of five limiting factors (label whether they are density-dependent or density-independent).
1.
2.
3.
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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
Biome
Food web
Decomposers
Trophic level
Omnivore
Pyramid of biomass
Limiting factor
Carrying capacity
Growth rate
Doubling time
Immigration
Emigration
Niche
Habitat
Parasitism
Commensalism
Abiotic
Pyramid of Numbers
Water cycle
Carbon cycle
Nitrogen fixation
Photosynthesis
Exponential (J-shaped) growth
Density-dependent limiting factors
Climax community
Community
Ecosystem
Consumers (primary, etc.)
Producers
Herbivore
Carnivore
Biotic
Abiotic
Population density
Eutrophication
Mortality
Natality
Predation (predator/prey)
Competition
Symbiosis
Mutualism
Ecological succession
Biotic
Pyramid of Energy
Food chain
Nitrogen cycle
Pioneer plant
Cellular respiration
Transpiration
Logistic (S-shaped) growth
Density-independent limiting factors
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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