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Reefs: Past, Present and Future

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Presentation on theme: "Reefs: Past, Present and Future"— Presentation transcript:

1 Reefs: Past, Present and Future

2 What is a Reef?

3 There are three basic kinds of coral reefs
Fringing reefs, barrier reefs and atolls Fringing reefs are coral reefs that grow in shallow waters and border the coast closely or are separated from it by a narrow stretch of water Fringing reefs consist of several zones that are characterized by their depth, the structure of the reef, and its plant and animal communities

4 Reef Zones

5 Barrier Reefs Barrier reefs are reefs that are separated from land by a lagoon. These reefs grow parallel to the coast and are large and continuous. Barrier reefs also include regions of coral formation that include the zones found in fringing reefs along with patch reefs (small reefs), back reefs (the shoreward side of the reef), as well as bank reefs (reefs that occur on deep bottom irregularities)

6 Atolls Atolls are annular reefs that develop at or near the surface of the sea when islands that are surrounded by reefs subside. Atolls separate a central lagoon and are circular or sub-circular. There are two types of atolls: deep sea atolls that rise from deep sea and those found on the continental shelf.

7 Animals Associated with Coral Reefs
Coral reefs provide habitats for a large variety of organisms. These organisms rely on corals as a source of food and shelter. Some organisms that use corals through mutualism, commensalism and parasitism are within the taxonomic groups Porifera (sponges), Polychaeta (worms), Gastropoda (snails), Crustacea (shrimp & crab), Echinodermata (sea urchins) and Pisces (fish).

8 Reefs: Past

9 Reefs through geological time
Reefs, in some shape or form, have been around for a very long time. Approximately 3.5 billion years ago microbialites (calcareous organo-sedimentary deposits) begin to appear in the fossil record. These benthic microbial communities produce their own hard substrate by sequestering raw inorganic materials from the surrounding seawater. For the next 2.5 billion years microbialites are represented by photosynthesizing cyanobacteria (blue-green algae)

10 Stromatolites

11 Stromatoporoids

12 El Capitan


14 Golden Spike Complex, Alberta
Upper Devonian Oil discovered + 40 years ago 4.5 billion barrels oil 17 trillion ft3 gas

15 Threat to coral reefs: Hobbyists
Hobbyists seeking fish and coral for their aquariums Aquarium owners are buying live coral at a rate that has increased 12 to 30 percent a year since 1990 The U.N. Convention on International Trade in Endangered Species (CITES) regulates trade for 2,000 species of coral Live fish, soft corals, anemones, crustaceans, mollusks and other creatures are not on the list Sea horse populations have dwindled by more than 25 percent since 1994

16 1997 I.Y.O.R. International Year of the Reef Reefs
One of earth’s most diverse ecosystems Home & nursery to 0.5 million fish species Potential for biomedical resources Protection against storms

17 Biomedical Applications
Over 6,000 unique chemical compounds Skin-Care Products Bone graft material Anti-Cancer Drugs Didemnin B, diazonomide A, dolastatin 10

18 Reefs in Crisis Pollution from poor land use, chemical loading, marine debris, and invasive alien species. Over-fishing and related harm to habitats by fishing gear and marine debris. Destructive fishing practices, such as cyanide and dynamite fishing that destroy large sections of reef and kill many species not yet harvested. Dredging and shoreline modification in connection with coastal navigation or development. Vessel groundings and anchoring that directly destroy corals and reef framework. Disease outbreaks that are increasingly prevalent in reef ecosystems. Global climate change and associated impacts such as coral bleaching, more frequent storms and rise in sea level.

19 Land-based Pollutants
Thermal Pollution Nutrient enrichment Sewage Agricultural runoff (fertilizers) Pesticides, herbicides Hydrocarbons (oil exploration, boats) Sedimentation coastal construction deforestation soil erosion


21 Overfishing Overfishing of herbivorous fish interacts with the effects of eutrophication to affect the community structure of coral reefs. Jamaica is a classic example of a phase shift from a coral reef dominated community to a macroalgal community

22 Selective overfishing
Selective overfishing of populations, for example spawning aggregations, can have particularly disastrous effects. one (1) 61cm female snapper produces the same number of eggs as two hundred and twelve (212) 41cm female snappers. 12.5kg of large snapper has the reproductive potential of 233kg of small snapper

23 Destructive fishing practices can destroy reef communities very effectively in a very short span of time. Dynamite fishing is an example that is also very dangerous for the human participants.

24 Destructive Fishing Cyanide fishing is a destructive fishing pratice common in southeast Asia. Cyanide (or bleach), when squirted into a crevice will temporarily stun fish for collection by hand. However, the cyanide also kills coral and other invertebrates near the fish's refuge

25 Reefs in Crisis 10% of existing reefs destroyed
30% threatened (destruction by 2020) 65% depleted within 2 generations Greatest risk areas Southeast Asia, East Africa & Caribbean

26 “Pollution, overfishing, and overuse have put many of our unique reefs at risk. Their disappearance would destroy the habitat of countless species. It would unravel the web of marine life that holds the potential for new chemicals, new medicines, unlocking new mysteries. It would have a devastating effect on the coastal communities from Cairns to Key West, Florida- communities whose livelihood depends upon the reefs.” President Bill Clinton, August 1996

27 CORAL REEFS The “rain forests of the sea,” coral reefs cover more than 6,500 square miles in the Caribbean, the Gulf of Mexico, off Florida and the Pacific. They are home to an estimated 550 species of fish, and are major tourist attractions

28 Economic Losses The loss of these fragile ecosystems would cost billions of dollars Tourism and fishing industries Tourism $1 billion generated annually by tourism at Australia’s Great Barrier Reef $1.6 billion by Florida’s reefs $90 billion by Caribbean reefs and beach tourism Fishing 6 million tons of fish also provide employment and protein for about 500 million people Damage to coastal regions that are currently protected by the coral reefs

29 Climate Projection Models
Fate of coral reefs if increases in the emission of greenhouse gases continued Corals can live only in water between 64 degrees and 86 degrees Farenheit, coral bleaching can be triggered by a temperature increase of just 1.8 degrees above the maximum “If we delay 10 years, the effect will be quite severe, and that’s what this model is showing us. A delay means the death of coral reefs for probably as much as 1,000 years.”(Hoegh-Guldberg , director of the Coral Reef Research Institute at Sydney University in Australia)

30 Coral Bleaching White spotting or dead areas
Increase in surface water temperatures stresses the coral Expulsion of zoozanthellae

31 Coral Bleaching

32 Losses A year 2000 report by the Global Coral Reef Monitoring Network concluded that 27% of the world’s coral reefs were “effectively lost”. The single largest cause was the El Nino-related warming event of , which destroyed 16% in 9 months. The remaining 11% were lost to sediment and nutrient pollution, over-fishing and mining of sand and rock.

33 Coral Bleaching- Consequences
Unless global warming is reversed- coral bleaching would increase in frequency and seriousness until it occurred annually everywhere as early as 2030. A single bleaching event will take reefs between 30 to 100 years to recover Global warming would devastate coral reefs by the middle of the 21st century and could eliminate them from most areas of the planet by 2100


35 Future March 2, 2000 — The intergovernmental U.S. Coral Reef Task Force unveiled the first-ever national plan to comprehensively and aggressively address the most pressing challenges facing reefs today FY 2000 Federal dollars specifically targeted to cooperatively saving reefs $6 million to NOAA and $5 million to the U.S. Department of the Interior. The President requested a total of $25 million for FY

36 National Plan Mapping Monitoring Marine Protected Areas
$1 million per year from NOAA), NOAA estimates that all U.S. coral reefs will be mapped by 2009. Monitoring integrated national reef monitoring system to profile and track the health of U.S. coral reefs. Marine Protected Areas expanding the existing network of coral reef protected areas All-Islands Coral Reef Initiative NOAA and the Department of the Interior will provide $1.35 million in FY 2000 to assist U.S. islands to improve coral reef management and protection, including monitoring, education and designation of marine protected areas.

37 For More Information 25 things you can do to save coral reefs
Reef Resource Page Coral Reef Protection Ramsar and Coral Reefs Planetary Coral Reef Foundation CORAL:The Coral Reef Alliance

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