Reefs: Past, Present and Future

What is a Reef?

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

Reef Zones

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)

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.

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).

Reefs: Past

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)

Stromatolites

Stromatoporoids

El Capitan

Golden Spike Complex, Alberta

Upper Devonian Oil discovered + 40

years ago 4.5 billion barrels oil 17 trillion ft3 gas

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

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

Biomedical Applications

Over 6,000 unique chemical compounds

Skin-Care Products Bone graft material Anti-Cancer Drugs

– Didemnin B, diazonomide A, dolastatin 10

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.

Land-based Pollutants Thermal Pollution Nutrient enrichment

– Sewage– Agricultural runoff (fertilizers)

Pesticides, herbicides Hydrocarbons (oil exploration, boats) Sedimentation

– coastal construction– deforestation– soil erosion

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

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

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.

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

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

“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

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

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

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)

Coral Bleaching

White spotting or dead areas

Increase in surface water temperatures stresses the coral

Expulsion of zoozanthellae

Coral Bleaching

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 1997-98, which destroyed 16% in 9 months.

The remaining 11% were lost to sediment and nutrient pollution, over-fishing and mining of sand and rock.

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

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 2001

National Plan

– Mapping $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 reefmanagement and protection, including monitoring, education and designation of marineprotected areas.

For More Information 25 things you can do to save coral reefs

– http://www.noaa.gov/public-affairs/25list.html Reef Resource Page

– http://www.indiana.edu/~reefpage/ Coral Reef Protection

– http://www.epa.gov/OWOW/oceans/coral/index.html Ramsar and Coral Reefs

– http://iucn.org/themes/ramsar/about_coral.htm Planetary Coral Reef Foundation

– http://pk.com/pcrf/ CORAL:The Coral Reef Alliance

– http://www.coral.org/