7th - Lesson 1 - What is a Coral Reef

Lesson 1: What Exactly is a Coral Reef?
Abstract
Students will gain an understanding of the basic components of a coral reef ecosystem, with
emphasis on specific abiotic and biotic factors crucial to reef health and trophic level
relationships among key organisms. Also included in the lesson is an opportunity for students to
learn about traditional, Polynesian culture and the native uses of coral reef resources. This is
accomplished through a PowerPoint presentation with corresponding student note-taking guide
and several short critical thinking group work opportunities throughout the lesson.
Learning Objectives
After participating in several group activities and viewing a PowerPoint presentation, students
will be able to identify several components of a coral reef habitat and categorize them into
abiotic factors, biotic factors, and trophic levels. Students will also be able to hypothesize about
possible human uses for coral reef resources.
Level
Middle school
Time Required
Two 50-minute class periods
California Science Education Standards (Grade 7)
Grade 7, Content Standard 3: Evolution--Biological evolution accounts for the diversity of
species developed through gradual processes over many generations. As a basis for
understanding this concept:
a. Students know both genetic variation and environmental factors are causes of evolution
and diversity of organisms.
b. Students know the reasoning used by Charles Darwin in reaching his conclusion that
natural selection is the mechanism of evolution.
e. Students know that extinction of a species occurs when the environment changes and
the adaptive characteristics of a species are insufficient for its survival.
Materials
Moorea Slide Show (Introduction PowerPoint)
Abiotic/biotic factor cards (one set per group of students)
Student Worksheets (note-taking guide)
Trophic Levels PowerPoint
Advance Preparation
* Make copies of student worksheets
* Copy and cut abiotic/biotic factor cards
Moorea Coral Reef Long Term Ecological Research Program
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Developed by Meghan Saxer as a part of the Research Experience for Teachers program
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Teacher Background
Biotic Factors: Trophic Levels in a Coral Reef
Coral reefs, like the majority of habitats on the planet, derive their energy from the sun.
Solar energy is converted into chemical energy by organisms conducting photosynthesis.
This chemical energy is then passed on to all other organisms within the system through
heterotrophic consumption. To put it simply, plants use sunlight to make sugar, some
animals get this sugar by eating the plants, and other animals get this energy by eating the
plant grazers. This transfer of energy can be tracked in a trophic level chart, like the one
below. Following the chart is a brief description of some of the organisms from each
trophic level.
Tertiary Consumers…
Large carnivores like black tip reef sharks,
moray eels, and black jacks.
Secondary Consumers…
Carnivorous organisms like trumpet fish and
yellowlined goatfish.
Primary Consumers…
Herbivorous organisms like zooplankton, striped surgeonfish,
dusky farmerfish, and brushtail tangs.
Primary Producers…
Photosynthetic organisms like phytoplankton, macro algae, and zooxanthellae
found inside coral tissue.
Primary Producers
The organisms within a coral reef system that conduct the initial conversion of solar energy into
chemical energy are various algae. Some algae work alone, like the fuzzy, filamentous algae
found on rocks and dead coral, or the thorny Turbonaria species. Other, smaller algae have
evolved to live within the cells of coral. Symbiotic algae within the coral are collectively called
zooxanthellae, or symbiodinium.
The algae and coral have a mutualistic relationship, meaning both species benefit from the union.
The coral provide algae with a protected environment and some of the compounds needed for
photosynthesis. In return, zooxanthellae produce oxygen and supply the coral with important
metabolic compounds (like glucose, glycerol, and amino acids). This microscopic,
photosynthetic alga is one of the most important primary producers within the coral reef system.
Coral itself is part of the animal kingdom. Almost all corals are colonial organisms, meaning that
large coral structures are made of hundreds to hundreds of thousands of individual animals. Each
individual animal is called a polyp. Polyps have a stomach that opens at one end that is
surrounded by a circle of tentacles. The polyp uses these tentacles for defense, to capture small
planktonic organisms for food, and to clear away debris.
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Corals can be categorized as primary producers because they house photosynthetic
zooxanthellae, but they can also be categorized as secondary consumers because they actively
prey on zooplankton. Scientists call organisms, like coral, that fit into more than one trophic
level mixotrophs.
NOTE: to keep the concept of trophic levels simple in this introductory lesson, corals will be
considered primary producers since the majority of their energy is derived from the
photosynthetic zooxanthellae directly within the polyp.
Primary Consumers
Primary consumers are the herbivorous organisms that are the first to obtain energy straight from
the source: algae making sugars through photosynthesis. Some organisms in this trophic level
graze on macro algae, like the filamentous algae that grow on dead coral and rock. Examples of
these organisms are brushtail tang, dusky farmer fish, and striped surgeonfish. At a smaller level,
microscopic zooplankton that feed on phytoplankton also fit into the primary consumer category.
Many organisms in the coral reef habitat use the coral structures as shelter, but coral polyps also
provide a tasty snack for some organisms as well. Examples of organisms that consume coral are
crown of thorns sea stars, bullethead parrotfish, and ornate butterfly fish. For this lesson, these
organisms are considered primary consumers since coral is categorized as a primary producer
(due to the zooxanthellae).
Secondary Consumers
The organisms in this trophic level are carnivores that consume algae-eating organisms.
Secondary consumers in coral reefs include trumpet fish, honeycomb groupers, and yellowlined
goatfish. These predators hunt small herbivorous fishes hiding within the coral.
Tertiary Consumers
The top-dogs in the coral reef are called tertiary consumers. These organisms eat the organisms
that eat the organisms that eat algae. Examples include moray eels and black tip reef sharks.
Although these organisms receive most of the spotlight at aquariums and in books, they are
completely dependant on all the trophic levels below them. If one of the lower levels fails, all the
levels above will be negatively affected as well. If coral die, many parrotfish will starve, so
grouper will not have enough to eat, which means less grouper for the sharks to eat. This is a
concept that should be stressed during this lesson! Teachers might even want students to
compare the interdependency of coral reef organisms with other, more familiar systems (like
grains-cows-humans).
Abitoic Factors: Affects on Coral Reef Ecosystem
The above explanation of a coral reef trophic system includes information only about the biotic
factors (the living organisms) in the habitat. So, how do the abiotic factors fit into this intricate
system?
Sunlight, Clear Water, and Water Depth: Because of their intimate relationship with
zooxanthellae, reef-building corals respond to the environment like plants. Algae need light for
Moorea Coral Reef Long Term Ecological Research Program
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photosynthesis, and light travels best through clear water. For this reason, coral reefs are
generally found in water with small amounts of suspended material, meaning not a lot of sand or
debris floating around.
Energy from the sun also diminishes with water depth—more water to penetrate means less
energy from the light. This prevents coral reefs from developing below ~50 meters of water.
Dissolved Oxygen and Temperature: Oxygen is an element required for respiration in living
organisms. Humans and other land organisms acquire oxygen in a gaseous state from the air, but
aquatic organisms obtain oxygen in a dissolved form. There is less oxygen in water than in air,
so coral reef organisms have evolved many adaptations for capturing as much oxygen as possible
(such as high surface area gills in fish).
The amount of dissolved oxygen also decreases as water temperature increases. For this reason,
organisms that live in areas with high water temperatures (such as coral reefs) need to have
adaptations that allow them to function in low oxygen environments. Of course, as sea
temperatures increase due to global climate change, species that do not adapt quickly might
begin to disappear.
Salinity: The ocean has a higher concentration of salt than the concentration of salt
within the bodies of most fishes. Since osmosis dictates a flow of water from high
concentration (low salt) to low concentration (high salt), fish within a coral reef tend to
lose water from their bodies to the surrounding environment. To compensate for this
water loss, the fish have adapted to drink salt water and actively excrete excess salt,
usually through the gills or through kidney function.
Many invertebrates (like coral) maintain the same amount of salt within their cells as the
surrounding ocean. This is a useful adaptation unless the salinity level in the ocean
becomes so high that it disrupts protein function within cells, which could lead to death.
Importance of Coral Reefs
Traditional Polynesia
The most important resource that coral reefs provided for native Polynesians was food.
The island peoples captured fish with nets, harpoons, baskets, and other tools. Canoes
fixed with outriggers were used as fishing vessels in lagoons. Fish rely on coral for
shelter and energy, so no coral means no food for people. The fish could be salted, eaten
raw, or prepared in many other ways. An important part of Polynesian culture was to
share the fish with all the people that helped in the catch, including not just the people on
the ocean but also those who helped prepare the tools.
Polynesian cultures also use items from the reef to make traditional ornaments. Shells,
coral pieces, fish bones and teeth were used to adorn headdresses, clothing, and jewelry.
The reef itself provided the native islanders with shelter from wave action. Often times
water outside the barrier reef can be rough, while at the same time the lagoon is relatively
calm. This helped control erosion and decrease the amount of damage caused by storms.
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Global Perspective
Coral reefs have an extremely high amount of biodiversity, more than any other marine
habitat. By studying these different organisms, scientists believe they have a chance to
find cures for human illnesses, like cancer, arthritis, bacterial infections, etc. This directly
affects all humans globally, no matter their relative proximity to a coral reef.
Resources
Background information for this lab was derived from the following websites:
NOAA education
http://oceanservice.noaa.gov/education/kits/corals/coral02_zooxanthellae.html
Osmoregulation and Excretion
http://academics.smcvt.edu/dfacey/animalphysiology/osmoregulation/answers.htm
Hawaiian Fishing Traditions
www2.hawaii.edu/~dennisk/texts/introfishing.html
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Instructional Procedure: Lesson 1, Introduction to Coral Reefs
Time
15 min
Instruction
Warm-up: The slideshow of coral reef
habitat, organisms and island scenes
(Introduction PowerPoint) is continuously
looping as students walk in the door.** If
possible, play traditional Tahitian music.
Have students write or draw 5
observations/ideas concerning the slides.
25 min
Ask each student to share orally one idea
with a partner at their table. Then initiate a
class discussion.
What are coral reefs? Categorization
Activity
At each table there are several cards with
pictures of coral reef abiotic or biotic
factors on the front and the name of that
object on the back.
The teacher explains that each of these
components is necessary to the health and
stability of a coral reef habitat. Students
must put the cards into categories of their
own choosing and be able to explain why
the items belong in those categories.
25 min
After students have identified their own
categories, the teacher explains the terms
abiotic and biotic. Students are now asked
to sort the cards into these two groups.
These groupings are recorded on the
student worksheets.
What are coral reefs? Information
Gathering
The teacher runs through a second
PowerPoint presentation that explains how
all of the items from the last activity fit
together within the coral reef ecosystem
(basically, the teacher outlines reef trophic
levels). Abiotic factors that could possibly
influence the development of organisms’
adaptations are given particular attention.
Reasoning
This introduction activity allows
students to identify with the content they
will be exploring more in depth in the
rest of the lesson. Students have a
chance to make their own personal
connections with the content, and to
share those connections with others.
Sharing in small groups first allows all
voices to be heard (even the shy ones),
and the whole group discussion opens
up multiple perspectives.
This activity allows students to begin
gaining familiarity with organisms and
other components of a coral reef.
When they are asked to group objects
themselves (without the teacher
dictating the categories) they look more
closely at objects and find interesting
connections (many that the teacher may
not have thought of him/herself!).
After defending their reasoning behind
the categories they created, the teacher
introduces new scientific terminology
(abiotic and biotic). Students then
demonstrate their understanding of these
vocabulary words by re-grouping their
cards.
Now that students have had a chance to
familiarize themselves with the key
players involved in the ecosystem, the
teacher can help them see how
everything fits together to make a stable
community.
The influence of abiotic factors on the
development of organism adaptations is
one of the state standards students are
required to know by the end of 7th grade.
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25 min
Students record facts about coral reefs on a
note-taking guide on the back of their
worksheets.
Polynesian Culture: How are humans
affected by coral reefs?
Students are told that they have been
stranded on an island. Within their table
groups, students brainstorm possible ways
in which they might benefit from the
nearby coral reef.
Ideas are shared briefly in a whole class
discussion.
10 min
The teacher explains how native peoples
on the islands utilize the resources
available due to the presence of coral reefs.
Students take notes on their worksheets.
Global Perspective: Why should we, in
Carpinteria, care about coral reefs?
Again, when you give students a chance
to come up with their own ideas, they
feel a greater connection to the scientific
material. This activity also encourages
students to develop their critical thinking
skills.
With the final presentation on how
humans really do use the coral reefs,
students can compare their own ideas to
those of a different culture.
Students are more engaged with a
subject they feel has an impact on their
lives.
Teacher initiates a class discussion based
on this question.
English Language Learner Modifications
As suggested in the SIOP model of ELL instruction, define a specific language objective for the
lesson. Provide appropriate sentence frames in a visible location to aid students in meeting the
language objective.
Example Objective: After discussing trophic levels, students will be able to make
inferences about several new organisms and communicate their ideas verbally with a partner.
Example Sentence Frames:
“I think that a _____________ is a ________________ because _______________”
farmer fish
primary consumer
its mouth is small and so it
would not be able to catch
other fish.
Enhancing Understanding (For Honors/GATE)
Students who have a good grasp of the content can be further challenged with these questions…
Humans have used coral reef resources and lived in close proximity to coral reefs for centuries.
How might human activity have impacted the organisms living in this ecosystem?
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Other than the examples given earlier in the lesson, what other abiotic factors might be present in
coral reefs? How do these factors affect the organisms living in this habitat?
Going Further (extensions for High School)
Independent research project with in class presentation. Assign each student a different island
that has coral reefs. Provide time in class for internet and library research. Students gather
information on human inhabitants, coral reef organisms, and the interactions between the two.
Students design their own presentation medium (PowerPoint, display board, 3-D models, etc.)
and present their findings to the class.
Assessment
Formative Assessment Opportunities
During the PowerPoint presentation, the teacher can monitor student responses to look for
concepts students are struggling with, which then allows the teacher to review the specific
content that students need help understanding.
Summative Assessment Opportunities
The students will each turn in their completed worksheets at the end of the lesson. This provides
the teacher with concrete responses for assessing what the students were able to gain from the
lesson, and can help pinpoint concepts that might need more attention in subsequent lessons.
Critical thinking skills were required for the abiotic factor/adaptation chart and for the wrap-up
questions, so specific attention should be paid to those portions of the worksheet.
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Name:__________________________________________Date:______________Period:______
Coral Reefs
Warm-up: In the box below, write and/or draw at least 5 observations about the
Warm-up
pictures in the slideshow.
Playing Cards: Study the cards at your table. What do these things have in
common? How are they different? Make categories for your cards and record them
below. Write a 1 sentence explanation for each category.
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What is a coral reef?
A coral reef is a _________________, a place where organisms live.
The reef is made up of coral, which are animals related to
___________________ and _________________.
Individuals are called _________________. Draw one here
Coral colonies build the large ___________________ of the reef as they grow.
Coral reefs provide _________________ and ___________ for many organisms,
like __________________ and ________________.
How do organisms get energy in a coral reef habitat?
_________________ make their own food.
________________ must eat others for food.
Another word for “make” is…
Another word for “eat” is…
Scientists use a ______________ chart to study the feeding relationships of
organisms in a habitat.
Tertiary (_________) Consumers
________ Carnivores
These living
organisms are
__________
Factors
Secondary (___________) Consumers
Carnivores: eat __________
Primary (__________) Consumers
Herbivores: eat ___________
Primary (__________) Producers
Make sugar through ___________________
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What are Abiotic Factors in a Coral Reef?
Biotic factors are ______________ parts of a habitat. Name 4 coral reef biotic
factors
Abiotic factors are _____________________ parts of a habitat. Organisms must
adapt to the abiotic factors in their environment in order to survive.
Brainstorm some of the possible adaptations coral reef organisms might have for
each of the following abiotic factors. Use complete sentences!!!
Abiotic
Factor
Organism
Adaptation
Sunlight
Clear Water
Water
Depth
Dissolved
Oxygen
Temperature
Salinity
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Why are coral reefs important?
You are stranded on a tropical island with the other people at your table, but you
are in luck! There are coral reefs in the lagoon around the island. How might you
use some of the coral reef abiotic and biotic factors to help you survive? You may
draw diagrams and/or write complete sentences to explain your ideas.
Native Polynesian uses of coral reef resources…
Put pic of jewelry, hat, dinner plate, waves crossed out
How might coral reefs help YOU?
Wrap-up
1. Name 2 biotic and 2 abiotic factors you might find in your backyard…
2. Barracuda fish can eat dusky farmerfish and yellow lined goatfish. To which
trophic level do barracuda belong?
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Name:______________Key____________________________Date:______________Period:___
Name:______________Key_______
_____________________Date:______________Period:___
Coral Reefs
Warm-up: In the box below, write and/or draw at least 5 observations about the
Warm-up
pictures in the slideshow.
Examples:
It looks tropical and warm
There are lots of fish.
Playing Cards: Study the cards at your table. What do these things have in
common? How are they different? Make categories for your cards and record them
below. Write a 1 sentence explanation for each category.
Example:
Fish
Not Fish
Brushtail tang
Sunlight
Shark
Oxygen
All the things in the first group are fish, and the items in
the second group are not fish.
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What is a coral reef?
A coral reef is a ______habitat_____, a place where organisms live.
The reef is made up of coral, which are animals related to
____anemones______ and ______jellies_______.
Individuals are called _____polyps_______. Draw one here
Coral colonies build the large ___structures___ of the reef as they grow.
Coral reefs provide ___space_______ and ___food________ for many organisms,
like _________sharks_________ and _______eels_________.
How do organisms get energy in a coral reef habitat?
___autotrophs_____ make their own food.
__heterotrophs_ must eat others for food.
Another word for “make” is… produce
Another word for “eat” is… consume
Scientists use a ____trophic__________ chart to study the feeding relationships of
organisms in a habitat.
Tertiary (__third___) Consumers
___Big____ Carnivores
Eat
sharks, morays
These living
organisms are
___biotic___
Factors
Secondary (__second___) Consumers
Carnivores: eat ____meat_____
Yellowlined goatfish
Eat
Primary (___first_______) Consumers
Herbivores: eat ___algae____
Dusky farmerfish
Eat
Primary (_____first_____) Producers
Make sugar through ______photosynthesis_______
Zooxanthallae, turbinaria
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What are Abiotic Factors in a Coral Reef?
Biotic factors are ____living__________ parts of a habitat. Name 4 coral reef
biotic factors sharks, brushtail tang, coral, hermit crabs
Abiotic factors are ____non-living_________________ parts of a habitat.
Organisms must adapt to the abiotic factors in their environment in order to
survive.
Brainstorm some of the possible adaptations coral reef organisms might have for
each of the following abiotic factors. Use complete sentences!!! Answers will vary
Abiotic
Factor
Organism
Adaptation
Sunlight
coral
Take up lots of space to get maximum
surface area for photosynthesis
Clear Water
Water Depth
Dissolved
Oxygen
Temperature
Salinity
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Why are coral reefs important?
You are stranded on a tropical island with the other people at your table, but you
are in luck! There are coral reefs in the lagoon around the island. How might you
use some of the coral reef abiotic and biotic factors to help you survive? You may
draw diagrams and/or write complete sentences to explain your ideas.
We could make a net out of palm
leaves and catch fish for dinner.
Native Polynesian uses of coral reef resources…
The students could draw pictures of jewelry, hats, dinner plate (food), waves
crossed out (less destruction)
How might coral reefs help YOU?
The biodiversity of the reef means there are more species to discover. One of these
could be a cure for cancer!
Wrap-up
3. Name 2 biotic and 2 abiotic factors you might find in your backyard…
Dog, tree, rocks, hose
4. Barracuda fish can eat dusky farmerfish and yellow lined goatfish. To which
trophic level do barracuda belong? Tertiary consumers
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Biotic Factor Cards: Primary Producers
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Biotic Factor Cards: Primary Consumers
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Biotic Factor Cards: Secondary Consumers
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Biotic Factor Cards: Tertiary Consumers
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Abiotic Factor Cards
Dissolved
Oxygen
Temperature
Clear Water
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Abiotic Factor Cards
Salinity
Sunlight
Water Depth
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