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Coral Reefs: The End?

Coral Reefs: The End?. Oceanography in the News New Species Discovered. A Marine Sanctuary. French Frigate Shoals, NW Hawaiian Islands--100 new species discovered (from Oct 31, 2006; www.sciencedaily.com.

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Coral Reefs: The End?

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  1. Coral Reefs: The End?

  2. Oceanography in the NewsNew Species Discovered A Marine Sanctuary French Frigate Shoals, NW Hawaiian Islands--100 new species discovered (from Oct 31, 2006; www.sciencedaily.com And from October, 2007; many new species discovered in biodiversity hotspot--Celebes Sea, off Indonesia http://news.nationalgeographic.com

  3. Red= warm currents / Black = cold currents /Orange= waterof 20°C or more Note orange zone and compare to coral reef distribution in next slide

  4. Orange= atolls /Red= fringing reefs /Green = barrier reefs

  5. Energy Flow in Reefs • The trophic pyramid for coral reef ecosystems • Diverse, mostly small organisms • Phytoplankton play a minor role!

  6. Australia - Great Barrier Reef 100 Km

  7. Barrier Reef

  8. General model of a platform-margin barrier reef presented by James (1983).

  9. Algal ridge

  10. Back reef Reef crest Fore reef

  11. 1

  12. back reef seascape branching coral

  13. Acropora palmata : Front reef

  14. 2

  15. Unhealthy signs • Coral “black band” disease (possibly a virus or bacterial infection) kills coral tissue, especially if corals are already under stress for some other environmental factor. • The Crown-of-Thorns starfish can wipe out huge tracts of coral reef. These occur in the western Pacific Ocean and proliferate rapidly when predators are somehow affected (human activity?)

  16. Corals in Decline • Many coral reef areas are in decline. Is this natural (have we been looking carefully for long enough?)? Or is is it anthropogenic in origin? • Beautiful appearing “white” corals are, unfortunately, not healthy • Upper panel shows “black band” disease progressing, while the lower panel is a brain coral that is “bleached”--expelled its zooxanthellae (?) Both in Florida reef tracts. Images courtesy Gene Shinn, USGS

  17. Unhealthy Signs • Parrot fish eating blue-green algae which is growing over coral • Below, urchins graze over coral heads (dead)

  18. Some Potential Contributors to Coral Reef Demise • Urbanization brings additional problems • Such as: • sediment (from development, agriculture) influx and • excess nutrients (effluents from sewage treatment, septic systems) • Overfishing (note: a general problem with popularity of reef fish for aquaria) USGS, Hawaii

  19. The Florida Keys wetlands Florida bay Florida reef tract keys

  20. Florida Reefs Florida Reefs--our legacy!

  21. Just to Add to the Corals’ Woes • Eugene Shinn, a USGS scientist, proposed recently that the ubiquitous African dust blowing westward off the Sahara might be responsible for some coral diseases (soil-borne microbes that infect polyps). Thus, humans may not be entirely responsible for the demise of coral reefs. • And there is more in Section 7…onward

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