Lab 5: Trouble in Paradise: Factors that Impact Coral Health

The lab activity described here was created by Erin Bardar and Sarah L Hill of TERC for the EarthLabs project.

Summary and Learning Objectives

In the previous lab, students explored the characteristics of the ocean environment in which coral reefs thrive. Unfortunately, there are a number of factors, both natural and anthropogenic anthropogenic - resulting from human activities , that can alter the ocean environment and threaten the health of coral reef ecosystems. In this activity, students will examine the local and global factors that disrupt corals.

After completing this investigation, students will be able to:

  • use basic Geographic Information System (GIS) data to evaluate threats on coral reefs;
  • explain how certain fishing practices, pollution, and climate change can damage coral ecosystems; and
  • describe the predicted consequences for coral reefs.

Open the Student Lab

Context for use

This activity follows Lab 4: Finding Coral's Ideal Environment, in which students explore the range of ocean characteristics preferred by coral reefs. Now that students are familiar with the environmental conditions in which corals survive and thrive, they are ready to explore the factors most likely to disrupt these conditions and threaten coral health and sustainability. It is recommended that students work in pairs or small groups for all three parts of this lab. The entire investigation should take approximately 2-3 class periods. Part A and the first step of Part B will take approximately 1.5-2 class periods (or 65 to 90 minutes). The readings and questions in Part B and Part C can be assigned for homework. Part C will take approximately one 45-minute class period.

Activity Overview and Teaching Materials

In Part A, students will download kml files and view them in Google Earth. The kml files from the World Resources Institutes 2011 program 'Reefs at Risk Revisited' allow students to view the image data on the global map and examine the severity of risks faced by coral reefs worldwide.

In Part B, students examine different examples of local threats and what they mean to the health of coral reefs. They also read a series of short articles about the impacts on coral reefs and watch four brief 2- to 4-minute videos to illustrate or further explain a local threat.

In Part C, students perform simple hands-on experiments designed to help them better understand the effects of ocean acidification on coral reefs and read several articles on different ways climate change can affect oceans and coral reefs. The following materials are needed for each group of 3-5 students:

  • 300 mL bromothymol blue pH indicator solution (available from any scientific supplier)
  • 500 mL beaker
  • drinking straw

Printable Materials

  • Activity Sheet ( and )
  • Reading - Local Reef Threats (Acrobat (PDF) 779kB Mar11 20)

Teaching notes and tips

Part A: If you do not have much experience with installing, navigating, and adding data to Google Earth, the lab will provide you with the information you need in order to practice and be prepared to support your students. You may also want to investigate a few tutorials before introducing the lab. For some tutorial ideas see the Additional Resources section below. Be sure to allow the students enough time for exploration and open-ended investigations with the Google Earth tool. Some schools may not have sufficient band-width or computers to run Google Earth, check your connections before trying this lab with students. If at all possible, download and install Google Earth software before class begins!

Regarding the Reef Threats KML files: The map for 2011 represents the integrated local threat index, without past thermal stress considered. Estimated threats in 2030 and 2050 use the 2011 local threat index as the base and also include the projections of future thermal stress and ocean acidification. The 2030 and 2050 projections assume no increase in local pressure on reefs and no reduction in local threats due to improved policies and management.

Part B: Have upper-level students work in pairs or small groups to explore one of the four categories of local threats. The groups can explore the news articles in the KML file and present findings about the threats to the class. There are at least four of each in the KML file, two images in Guam are for the same news piece. Students can also search online for more information on a particular threat or use links in the Optional Extension at the bottom of the student webpage. There may be some overlap among groups if they search for their own information since threats they find in research or news articles may fall within several threat categories as defined for use in this Lab.

Part C: If you are concerned about student safety, the experiment with bromothymol blue in Part C can be performed as a teacher demonstration. If you are doing this lab online, you can have students watch the following Bromothymol Blue + CO2 video, which shows the same. The video is on Student pages in the Extension section at the bottom of the page. Note that the video was created for another curriculum, so there are questions the narrator asks for another class that are not relevant to this specific lab.

Regarding the short video "Aragonite Saturation and Coral Reef Distribution." This video includes a brief narration by one of the lead authors on the paper that explains it. There is some information on the student page to help decode some of what the scientist says in her narration. CMIP5 stands for "Coupled Model Intercomparison Project Phase 5" and was a collaborative effort by 20 international climate modeling groups as part of a research program to improve estimates of climate change. Their findings were summarized in the 5th Assessment Report of the IPCC. The CMIP project has been in place since 1995; the current group is CMIP6.

The narrator also refers to RCP 8.5. RCP stands for "Representative Concentration Pathway," which is a term for a type of modeling scenario. There are 4 scenarios, which have alternative trajectories for CO2 emissions and resulting atmospheric concentrations from the year 2000 to 2100. RCP 8.5, also known as the "business as usual" trajectory, is considered the "nightmare" scenario because it assumes that emissions to CO2 continue to increase, the current trends of agricultural and grass lands increasing simultaneously with forest cover decreasing continue, and economic growth remains low in developing countries. The 8.5 in the name refers to the global energy imbalance, measured in watts per square meter, by the year 2100. If students are not familiar with climate models, it might be good to discuss some basics about climate modeling and different RCP scenarios. See the Additional Resources below for more information.

If you would like your students to learn more about ocean acidification, Lab 7 of the Carbon module is devoted to that issue and includes the same lab experiment used here.


You can assess student understanding of topics addressed in this Investigation by grading their responses to the Stop and Think questions.

State and National Science Teaching Standards

Additional Resources

Background Information

Google Earth Tutorials