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Biosphere, Hydrosphere, Oceans



Coral reefs comprise some of the greatest areas of biodiversity on Earth, rivaling the biodiversity of the rain forests. Like the tropical rain forests, coral reefs are found only in the tropical and semitropical areas of the world, generally within 30 degrees latitude of the equator.

Coral reefs need specific environmental conditions to survive. They grow best in sunny, shallow, clear water, so that the reef can get lots of sunlight. They prefer salt water, doing poorly in areas where there is a lot of river runoff. This is not only due to the infusion of freshwater, but also the silt, which can cover a reef or muddy the water and block the sunlight. The best temperature for coral reefs is between 25 and 31 degrees C (77 and 88 F) and the best salinity is between 34 and 37 parts per 1,000. These conditions are most often found in the tropics and subtropics.

The current coral reefs resulted from production that occurred over the past five to ten thousand years. The actual coral makes up only a small part of the life found on the reefs but provides habitat for numerous other species. Coral reefs play an important role in providing a food source and a living for many people, especially in developing nations such as the Philippines and the Dominican Republic. Anticancer drugs and painkillers have been developed from coral reef products. Research is now being done on a method to encourage bone growth in humans by mimicking the coral secretions. Additionally, coral reefs play an important role in biogeochemical cycles, especially the carbon cycle.

As of late 2005, an estimated 20 percent of the world's coral reefs had been "effectively destroyed" - showing live coral losses of at least 90 percent and no immediate prospects for recovery - according to the Global Coral Reef Monitoring Network. Another 24 percent face imminent risk of collapse as a result of human pressures and 26 percent face longer-term loss-bringing the share of world reefs now threatened or destroyed to 70 percent, up from 59 percent in 2000.

Most scientists believe reef degradation occurs in response to both natural (e.g., severe weather) and human-caused stresses (e.g., over-fishing, coastal development). Recent research points to the impact of climate change and warming ocean temperatures on coral reefs.

Coral disease outbreaks have struck the healthiest sections of Australia's Great Barrier Reef, where for the first time researchers have conclusively linked disease severity and ocean temperature. Close living quarters among coral may make it easy for infection to spread, researchers announced in May 2007.

"With this study, speculation about the impacts of global warming on the spread of infectious diseases among susceptible marine species has been brought to an end," said Don Rice, director of the National Science Foundation (NSF) Chemical Oceanography Program, which funded the research through the joint NSF-National Institutes of Health Ecology of Infectious Diseases Program. The research was also funded by the NOAA Coral Reef Conservation Program, among other agencies.

The colorful coral colonies that attract visitors to the Great Barrier Reef live atop a limestone scaffolding built from the calcium carbonate secretions of each tiny coral, or polyp. While polyps provide the framework, coral's vivid hues come from symbiotic single-celled algae that live in the polyps. The algae supply much of the food coral need to survive.

When disease or stressful environmental conditions strike a coral colony, the polyps expel their algae. This algae loss makes the coral appear pale.

"We're left with a big question. Can corals and other marine species successfully adapt or evolve, when faced with such change?" Rice said.



Coral reef scientists and managers from 45 countries met in October 2006 at the International Tropical Marine Ecosystems Management Symposium (ITMEMS) conference in Cozumel, Mexico. There they reported the emerging impacts of climate change on coral reef ecosystems.

Their official statement: "There is no longer any doubt that the Earth's climate is changing, causing rapidly warming seas and ocean acidification. Warming seas are causing increased mass coral bleaching and mortality, with little evidence that corals and their symbionts can evolve fast enough to keep pace."

The International Coral Reef Initiative (ICRI) has approached your team to conduct a thorough assessment of the risk and vulnerability of coral reefs to climate change. ICRI is particularly interested in your recommendations of how to deal with the situation. They plan to use your recommendations for a major campaign to promote reef conservation during the 2008 International Year of the Reef.


Date: 5/10/2007

Scenario Images:

Coral Reef
Credit: Florida Keys National Marine Sanctuary (from the NOAA Coral Kingdom Collection)

Reefs at Risk
Reefs at Risk: Estimated threats to the world's reefs from human impacts (red = high, yellow = medium, blue = low). Source: ReefBase Interactive Map Server and World Resources Institute.



Coral Reef Ecology (Cycle A)
This site from the Biology Department at the College of Charleston presents various areas of coral reef research. Of particular interest are "Coral Optics and Remote Sensing" and "NASA/CMC Remote Sensing of Coral Reefs."


Coral Reef Images (Cycle A)
Landsat 7 images of the world's coral reefs.


Coral Reefs (Encyclopedia of the Earth) (Cycle A)
Read about coral reefs at the online Encylopedia of the Earth.


Coral Reefs: Rainforests of the Sea (Cycle A)
Join the Oceanic Research Group to learn how coral reefs grow, why they are important, what is threatening them and how everyone can help save them. You can view the entire movie (20 minutes) online; you can also read the entire script online. The movie is geared for audiences 13-adult.


Mapping the Decline of the Coral Reefs (Cycle A)
This article from NASA's Earth Observatory examines the reasons why since 1980 we have seen a rapid decline in the vitality of coral reefs and their ecosystems worldwide.


NOAA Coral Reef Conservation Program (Cycle A)
This National Oceanic and Atmospheric Administration (NOAA) program supports effective management and sound science to preserve, sustain and restore valuable coral reef ecosystems.


NOAA's Coral Reef Information System (CoRIS) (Cycle A)
CoRIS is designed to be a single point of access to NOAA coral reef information and data products, especially those derived from NOAA's Coral Reef Conservation Program.


NOAA Current Operational Coral Bleaching HotSpots (Cycle B)
Monthly Sea Surface Temperature (SST) measurements for the Eastern and Western Hemispheres are reported as degrees above the climatological monthly maximum temperature. The plots are useful as indicators of coral bleaching hot spots, which occur at 1 degree above monthly climatological maximum temperature. Hotspots for 2017 are at the top of this page; scroll down for hotspots from 1997-2016


NOAA's Coral Bleaching Indices (Cycle B)
The Tropical Ocean Coral Bleaching Indices web page is designed by NOAA Coral Reef Watch to provide near-real-time information (2000-present) on thermal stress that induces coral bleaching for 24 selected reef sites around the globe. The information is extracted from near-real-time satellite remotely sensed global sea surface temperature (SST) measurements and derived indices of coral bleaching related thermal stress from 50 km water pixels surrounding or close to these reef sites.


Ocean World (Cycle B)
Resource from Texas A&M University that presents the latest in oceanography information and topics including Coral Reefs.


ReefBase Global Information System (Cycle B)
Source: World Fish Center, World Resources Institute and others
Provides country-level data and information, organized in the following categories: Resources, Threats, Status and Management. Users need to register (free) to have full access to GIS/database.


Sustainable Ecosystems Institute (Cycle B)
This report discusses the diversity and health of the reefs of Montserrat, the impacts of volcanic activity, and the potentials and hazards of ecotourism.


USGS Pacific Coral Reef Website (Cycle B)
This gateway provides access to United States Geological Survey (USGS) studies of coral reefs in the Pacific Ocean, especially in the Hawaiian Islands where efforts are focused on mapping, monitoring, remote sensing, sediment transport studies, and collection of tide, wave, and current data from remote stations.


Coral Reefs and Climate Change Education Packages (Cycle C)
CoralWatch-University of Queensland (Australia) has developed Coral Reefs and Climate Change: The Guide to Education and Awareness. Includes reef activities, CD and coral health chart. Select Education to access information about Classroom packages available for purchase.


Exploring Paleoclimatology in the Classroom Using Coral Radioisotope Data (Cycle C)
Source: World Data Center for Paleoclimatology (NOAA/NCDC). This guide provides instructions for educators on how to access and use coral radioisotope data (from 1726 to 1997) for classroom activities. The data consist of strontium and calcium ratios (Sr/Ca) and Sea Surface Temperatures (SST) for coral samples near Rarotonga Island in the South Specific gyre. Topics include methods for reconstructing temperature records, the South Pacific Gyre and EL Nino/Southern Oscillation (ENSO), and the relevance of decadal variations in sea surface temperature. Students will learn to use the data to generate graphs comparing Sr/Ca ratios to historical temperature data and to calculate the statistical relationship between isotope ratios and temperature. They may also use linear regression analyses to compare and evaluate methods for reconstructing climate history and interpret chemical data from coral samples. A link to the dataset website and to links for additional references are also provided. Grade level: High School (9-12)


Keeping Watch on Coral Reefs (Cycle C)
In this lesson, participants will investigate the current state of management of coral reefs. They will discover why coral reefs are important and what can be done to protect them. Students will be able to identify and explain ways that coral reefs benefit human beings, identify and explain major threats to coral reefs, describe major components of the Coral Reef Early Warning System, identify and discuss actions that can be undertaken to reduce or eliminate threats, and be able to obtain and analyze several types of oceanographic data from remote-sensing satellites.


NASA has developed microsets of Earth science data for K-12 education, which can be used with existing curriculum and enable students to practice math skills using real measurements of Earth system variables and processes.

The microsets are created using data from NASA Earth science satellite missions and provide information on the atmosphere, ocean and land surface. New data types continue to be added to the collection. Data is available online along with K-12 lesson plans, computer tools and an Earth science glossary.

Use the Live Access Server to create your own microsets of NASA data. The LAS contains over 128 parameters in atmospheric and Earth science from five NASA scientific projects Click here for an overview of the parameters and time period available.


U.S. Coral Reef Taskforce (Cycle C)
Government task force created in 1998 to research, monitor and conserve coral reefs. Site includes: background on coral reef habitats; reef ecology and environmental requirements; environmental requirements of reefs; reef functions and significance; natural and human threats to reefs. Also covered are: Task Force actions; policies and partnerships; and the National Action Plan for Coral Reef Conservation.


Sample Investigations:


Exploring the Environment: Coral Reefs (Cycle A)
Though coral reefs cover less than .2 percent of the ocean's bottom, they contain 25 percet of all marine life. Yet, experts say coral reefs are isappearing. And fast. What could or should be done. A NASA Classroom of the Future - site featuring Problem-Based Learning activities.
Difficulty: intermediate


NOAA Coral Reef Watch (Cycle A)
This page contains a listing of various NOAA coral reef data available for analysis. Google Earth links allow users the opportunity to visualize variables on a virtual Earth.
Difficulty: beginner


Coral Reefs In Hot Water (Cycle B)
This activity explores the potential impact of climate variability and change on coral reefs. Designed to tap specific skills and knowledge through scientific inquiry, the activity more generally seeks to stimulate thought about the long-term impacts of a warmer planet. For grades 5-8.
Difficulty: intermediate


My NASA Data: Coral Bleaching in the Caribbean (Cycle C)
Students use satellite data to determine when the sea surface temperature meets the criteria to induce coral bleaching. Learning Outcomes: Students will practice analyzing images, maps and graphs from Internet-based educational resources. Students will explore the correlation between sea surface temperature and coral bleaching.

MY NASA DATA microsets are created using data from NASA Earth science satellite missions and provide information on the atmosphere, ocean and land surface. Data is easily-accessible online along with lesson plans, computer tools and an Earth science glossary. You can link to the MY NASA DATA Live Access Server (LAS) where you can select items (microsets of data) from the menu (list of datasets) using descriptions (parameters and time frames) of the items. For grades 5-12.
Difficulty: intermediate




  • Science
    National Science Education Standards - Science Content Standards The science content standards outline what students should know, understand, and be able to do in the natural sciences over the course of K-12 education.
      • Science as Inquiry (Std A)
        • Understanding about scientific inquiry
      • Life Science (Std C)
        • Structure and function in living systems
        • Regulation and behavior
        • Diversity and adaptations of organisms
      • Earth and Space Science (Std D)
        • Structure of the earth system
      • Science in Personal and Social Perspectives (Std F)
        • Populations, resources, and environments
      • Science as Inquiry (Std A)
        • Abilities necessary to do scientific inquiry
      • Life Science (Std C)
        • Interdependence of organisms
        • Matter, energy, and organization in living systems
      • Earth and Space Science (Std D)
        • Energy in the earth system
      • Science in Personal and Social Perspectives (Std F)
        • Natural resources
        • Environmental quality
        • Natural and human-induced hazards
        • Science and technology in local, national, and global challenges
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