Coral Reef Ecology Program

Grades 4-8, length: 60 min


Program Description: Explore the underwater world as you act as a marine biologist to assess the health of Hawaii’s coral reefs. In a comparison of Northwestern and Main Hawaiian Island coral reef ecosystems, students use the scientific method to identify threats facing coral reefs and determine how, why, and where they occur. Students also identify different types of coral, handle real specimens, and observe coral structure up-close under microscopes.


Learning Objectives:

-       To discover the difference between relatively healthy reefs in the Northwestern Hawaiian Islands and degraded reefs in the Main Hawaiian Islands.

-       To hypothesize and investigate the reasons for this difference and discover how, where, and why coral reefs are threatened.

-       To understand human impacts on coral and generate solutions to better care for coral reefs, including personal actions on land that can affect ocean health.

-       To realize the importance of coral reefs ecologically, culturally, medicinally, and economically.

-       To identify three main species of coral found in the Hawaiian Islands and observe coral structure under a microscope.



Blue tarp

Topographic maps of the Main Hawaiian Islands

Projector, computer, and slideshow presentation

Large images of 1. healthy reef and 2. dead reef

Laminated images of different impacts on coral reefs (x 15)

Laminated site lists (x 15)

Laminated coral reef identification sheets (x 15)

Laminated diseases and impacts on coral reefs reference sheets (x 15)

Laminated site list/impacts answer key with background info for presenter (x 1)

3 large coral specimens, 2 mushroom coral, 1 starfish, 1 crown of thorns,

3 Microscopes

3 pucks with coral specimens inside

Coral specimens grown under differing pH levels


Program Outline:


I.               Welcome and Introduction

-       From Bishop Museum

-       What is Holoholo Science?


II.             Coral Reef Ecology Overview

-       We will be learning about coral reef ecology by comparing a healthy reef in the Northwestern Hawaiian Islands to reefs in the Main Hawaiian Islands that are suffering from various impacts. You will become the scientists and figure out what these threats to coral reefs are, where they happen, and why!


III.           Powerpoint Presentation

-       The State of Hawaii includes not only the Main Hawaiian Islands that we are all familiar with (Niihau, Kauai, Oahu, Molokai, Lāna’i, Maui, and the Big Island) but also a chain of islands and atolls to the Northwest of the main islands.

-       The Northwestern Hawaiian Islands and surrounding waters are protected in the largest marine wildlife reserve in the world, called Papahānaumokuākea Marine National Monument.

-       The Northwestern Hawaiian Islands are 2,500 miles from the nearest continent, and because of this isolation they are home to a diverse ecosystem with many unique species. Explain the meaning of the word ‘diversity’.

-       They are also home to an extensive coral reef ecosystem (70% of all coral reefs in the U.S. are found here!) that provides a home for over 7000 marine species!

-       What is coral?

-       Coral might sometimes look like rock but actually it is a living animal. Corals are related to jellies, they have tentacles like jellies and even have a stomach!

-       Coral Reef Polyp activity: ask for a volunteer to come up and transform their hand into a coral polyp! Put on glove and place Styrofoam cylinder around hand. This shows the structure of a coral polyp and the dots represent the zooxanthellae.

-       Coral and zooxanthellae have a mutualistic relationship, which means they help each other. Zooxanthellae are tiny plant cells that perform photosynthesis to make nutrients for the coral. In return, coral provides the zooxanthellae with shelter and protection. The zooxanthellae also give the coral its beautiful colors.

-       Most coral polyps live together in colonies (show muffin tin as an example). Coral polyps remove calcium from the sea water to build their skeletons that form the foundations of coral reefs. As colonies grow over hundreds of thousands of years, they join with other colonies to become reefs. Some coral reefs began growing 50 million years ago!

-       Coral reefs are sometimes called the “rainforests of the sea” because of the diversity of life they provide a home for. Although they cover less than 1% of the ocean floor, they support ¼ of all marine creatures.

-       Where do corals grow? Show maps on powerpoint, red dots are areas where corals grow.

-       Coral can only grow in warmer ocean water, which means we find them in the tropics.

-       Corals need sunlight to grow (so that the zooxanthellae can photosynthesize and make food for them), and so they are found mostly in shallow waters where the light can reach them.

-       Three main types of Coral found in Hawaii:

-       1. Montipora (Scientific name): can be bright blue or purple, and tan, brown, or cream colored. Their surface is irregular and looks like rice, so they are called rice corals.

-       2. Porites: Often a bright green color but can also be olive green, brown, yellowish, or blue-grey. They look like lobes and have a smooth surface, so we call them smooth coral.

-       3. Pocillopora: Ball-shaped with different lengths and thicknesses of branches. Looks like cauliflower heads, we call them branching corals.

-       Show large pictures of healthy coral reef in French Frigate Shoals compared to a dead reef off Oahu.

-       We are going to use the scientific method to try and understand what is happening here.

-       1. Observation: Reefs in the NWHI are much healthier than reefs in the Main Hawaiian Islands

-       2. Question: Why?

-       3. Formulate a hypothesis: ask the kids about threats to coral reefs and list their answers on the board (supplementing where necessary). Factors to consider:


-     Marine debris (discarded hooks, line, and nets)

-       Snorkelers/divers trampling and breaking live coral

-       Small boats running aground on coral (sometimes you can even see paint on the coral from the bottom of boats)

-       Boat and ship anchors damaging corals

-       Over fishing

-       People feeding fish

-       Disease (sometimes due to stress from being damaged, often appears as a pinking on the coral)

-       Coral bleaching (warmer water due to climate change cause the coral to expel their zooxanthellae and turn white)

-       Invasive species (invasive algae is a big problem in the islands, usually introduced from elsewhere and can smoother the coral)

-       Predation by reef fish and starfish.

-       Crown of thorns

(background info: The crown of thorns is a large, nocturnal and carnivorous sea star that preys on coral reef polyps. It is endemic to coral reefs in the Red Sea, Indian Ocean, and Pacific Ocean. One single starfish can eat up to 6 square meters of living coral per year. Population outbreaks are thought in part to be due to algal blooms from agricultural run-off that supply the starfish with excess nutrients. Before these outbreaks, balanced populations of crown of thorns prevented faster growing coral from overtaking slower growing corals).

-       Run-off and sedimentation from land (agriculture, clearing forests, etc)

-       Ocean acidification (to address after activity – this is not one of impacts in activity)


- Explain that we are going to work in teams to identify these impacts, figure out where they are happening and why they are happening.


IV.           Activity

  1. Create map of Main Hawaiian Islands: ask for volunteers to help you lay out blue tarp (the Pacific Ocean) and align the topographic maps appropriately to create the Hawaiian chain.
  2. Point out the numbered red dots. Explain that each team will get an image of a coral reef impact that was photographed at one of the locations marked by the red dots. Each team will also get a list and description of each site. Their job is to identify the impact and match the image to a site. Explain that they will also have a reference sheet with pictures of certain threats to corals that they can use as a guide. But, not every impact will be pictured on the reference sheet.
  3. Once they have identified their impact and matched it with a location, ask the kids to use the coral reef identification sheet to try and identify any living coral they can see in their image as one of the three main species we reviewed earlier. Real specimens of each coral species will be on the reference table with microscopes to look at them in detail. Point out that there are also specimens of mushroom corals (that are one single polyp instead of a colony), a star fish, and a crown of thorns star fish
  4. Make a chart on the board with columns for Image (A-P), Impact, Location, and Coral Species name. Depending on time, either you can fill this out yourself during the discussion or have the kids fill it in themselves.
  5. Discussion – run through each teams’ findings, show the image to the whole class, and briefly explain the impact.
  6. Return to the Scientific method slide. Did you discover that some of the threats you hypothesized about are actually happening and impacting the coral? What is your conclusion about why the coral reefs of the NWHI are healthier than in the main islands?
  7. If there is time, discuss the impact of ocean acidification: As we emit more carbon dioxide into the atmosphere from burning fossil fuels, much of that carbon dioxide is absorbed by the ocean. This is changing the ocean’s chemistry and creating what is called ocean acidification. This change presents a challenge to any organism with a calcium shell or skeleton. For coral, ocean acidification causes them to grow at a slower rate and can even dissolve their calcium skeletons.

Show samples of two different corals grown under different conditions by a scientist at coconut island. Prior to the experiment, the coral was dyed pink so that the new growth could be obvious under different conditions. One coral was placed in water of a pH that we have today and the other of a pH expected in 100 years as we change the ocean’s chemistry. The coral that was growing in more acidic water has stunted growth compared to the other.


V.             Conclusion

Why are Coral Reefs Important?

-       A foundation of life in the ocean, home and breeding ground for fish and other  marine life.

-       Important source of medicines to treat cancer, arthritis, infections, heart disease, and other diseases.

-       Important source of food for many people around the world – without the reef, many fish would not have a home, and people depend on fish for food and income

-       Economy – important source of income in terms of fishing and in terms of tourism

-       Coral reefs provide a natural barrier, protecting the shoreline from big waves, storms, and floods.

-       Culture – coral is the first living animal mentioned in the Kumulipo, or Hawaiian creation chant. Hawaiians also used coral as tools.

-       The reefs we have today cannot be replaced, coral grows slowly, only about 1cm per year! We must take care of this magnificent and important ecosystem in the present and for future generations.


What can we do to protect them?

Discuss ways to help protect coral reefs from the impacts we have learned about.

-       climate change: reducing our emissions of carbon dioxide

-       being responsible about our trash

-       being careful snorkelers

-       if you fish or go out on boats, be sure to take all hooks and line with you and only anchor on sandy bottoms.

-       Try not to use herbicides and pesticides that put extra nutrients into our watershed and end up in the ocean. These extra nutrients encourage the growth of algae that blanket the coral reef.

-       Try to apply sunscreen after you come out of the ocean or well before you go into the ocean because chemicals in sunscreen might be harmful to coral reefs.

Remind students that some of the impacts we explored today are natural (like predation by parrotfish), but human impacts are putting extra stress on coral reefs and making it hard for them to survive. We have the ability to help protect coral reefs by everyday actions we take on land.