Astronaut Photography - Observing Earth's Systems from Space

Coral Reefs

An oversupply of nutrients from soils is often directly related to agricultural and forestry practices on land; deforestation through burning can have similar effects, putting an oversupply of nutrients into ocean. In Indonesia in late 1997, forest fires in Indonesia related to El Nino¹⁹-induced drought indirectly killed almost the entire 400-kilometer Mentawai coral reef system off the coast of Sumatra. Not only the coral died - the entire ecosystem including fish and plants was killed by a "red tide" - a massive planktonic bloom whose overgrowth can block sunlight, killing other plants in the ocean. As the algae die, their decay can consume all oxygen in the water, killing animal life. Many of these fires were intentionally lighted to clear new land for agriculture or to manage forests, as is the case in Madagascar. This common practice became disastrous when El Nino caused rainfall deficits, and "managed" fires went out of control. The smoke from these fires, shown top left²⁰ in a photograph from the Space Shuttle, carried iron and other nutrients directly over the coral reef where they settled out and fertilized the massive red tide that overwhelmed the reef system.

19. (http://earthobservatory.nasa.gov/Library/ElNino/ What is El Nino?)

20. (http://earthobservatory.nasa.gov/Study/CoralDeath/ A Dangerous Intersection: Humans and Climate Destroy Reef Ecosystem)

Coral reefs sustain some of the most diverse ecosystems on Earth. Reefs protect coastlines from erosion while supporting fisheries and sustaining economies around the world, and they are a specific target of Crew Earth Observations. In addition to El Nino-induced drought effects, coral reef threats also include agricultural and industrial runoff, dust storms, and sea-water warming associated with global warming. Crew Earth Observation photographic acquisitions, along with historical astronaut photographs going back 35 years, are supporting scientists' efforts to map and monitor reefs around the world.

Foreword >>
Introduction >>
Crew Earth Observations >>
          Dynamic Events >>
          Coral Reefs >>
          El Nino >>
          Smog >>
          Volcanic Eruptions >>
          Deltas >>
          Urban Areas >>
          Glaciers >>
References >>