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Coral Reefs: Cycle A

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1). 95% of the world's reefs have been damaged by over-fishing, dynamiting, poisoning, pollution, or ship anchors

2). As a living organism, coral reefs can be affected by a variety of diseases such as white pox, rapid wasting disease, patchy necrosis, white plague, and black band disease. The number of coral reefs affected by diseases has increased. Scientists believe that changes in the ecosystem have made corals increasingly susceptible to scourges that have long existed in ocean waters

3). Coral reefs represent some of the greatest concentration of biodiversity on Earth

4). Research into historical coral reefs changes and their effect on the global ecosystem reveal information for today. Current coral reefs resulted from production that occurred over the past 5000-10,000 years

5). Coral reefs play an important role in the carbon cycle, capturing it and converting it to calcium carbonate

6). Corals carry in their tissues symbiotic algae that allow the host to produce more oxygen than they consume

7). Coral reefs filter water and increase its quality. Poor water quality is the primary cause of reef destruction including fertilizers and pesticides in runoff. Loss of wetlands and mangrove forests that absorb massive amounts of nutrients and sediment that favor algal blooms and other species that disrupt the balance of the reef

8). Coral reefs are influenced by turbidity, light, oxygen levels, nutrients, temperature, salinity, pH, and total suspended solids, El Nino Coral reefs are sources of medicines


Scenario: 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.


Author: ESSEA Project, IGES



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.



  • 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

Individual Assignment

Sphere Group Study

During this cycle you will become "experts" in the relationship of individual spheres. You will need to study the resources listed under readings, discuss your key ideas in your sphere group discussion space, and then submit your group's work for a grade.

Go to the course discussion space to find out which sphere you are studying during this module.

Read the scenario.


First, submit your individual questions and prior knowledge about this event and Earth system science to your sphere group discussion space. Then prepare a document about your prior knowledge and upload it to ESSEA.


  • Review the Individual Reflection Rubric.
  • Read the scenario.
  • Discuss your ideas about the effect of this event on your sphere in your sphere group discussion space.
  • Prepare and upload your prior knowledge reflection document to ESSEA.
  • Complete the individual reflection rubric.

Deadline: Wednesday, October 31 2018 11:59 PM (Eastern Time)
Upload Assignments
Team Assignment


  • Review the Group Sphere Study Rubric.
  • Describe your sphere in detail in the sphere group discussion space so you can share it with your Event Team next cycle. Refer to An Example of an ESS Analysis reading if you would like to review causal relationships.

Upload your group's most accurate analysis of the Sphere - Event interactions with reasoning and support to ESSEA and complete the rubric.
Deadline: Sunday, November 4 2018 11:59 PM (Eastern Time)
Upload Assignments

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 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.

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