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Coral Reefs: Cycle B

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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

Team Assignment
<Event Team Study

This cycle you and your Event Team will build on the sphere to sphere interactions you identified last cycle to synthesize them into causal chains or causal matrices. You will use the resources listed under Readings, discuss your ideas in the event team discussion space, and then submit your team's work to ESSEA for a grade.



  • Read about the scenario.
  • Review the Team Event Study Rubric.
  • Serve as a "Sphere Expert" to your Event Team.
  • Read your teammates' summaries about the other individual sphere effects.
  • Identify intersecting and overlapping effects in your event team discussion space. Refer to An Example of an ESS Analysis reading if you would like to review causal relationships.
Upload to ESSEA your team's most accurate analysis of the Earth System interactions with reasoning and support and complete the team rubric.
Deadline: Sunday, November 11 2018 11:59 PM (Eastern Time)
Upload Assignments

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

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.

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