The loss of live coral is an acknowledged symptom of CORAL REEF degradation. .

1. The loss of live coral is an acknowledged symptom of CORAL REEF degradation. .

2. Citation • Côté, Isabelle M & John Bruno, 2008. "Patterns of Caribbean coral loss." In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [Published in the Encyclopedia of Earth December 27, 2008; Retrieved May 11, 2009]. <http://www.eoearth.org/article/Patterns_of_Caribbean_coral_loss>

3. Do not forget to explore top related websites and supplementary reading among other features in this week’s Environment in Focus.

4. The first large-scale measurement of coral loss was made for the Caribbean basin. In this region, there has been an 80% decline in coral cover since the mid 1970s

5. Loss of live coral cover on Caribbean reefs since 1977. (Modified from Gardner et al. 2003; Photos by I.M. Côté)

6. Although low coral cover was once thought to be an alternative and stable ecosystem state, there is now evidence that reefs can return to a coral-dominated condition.

7. There is a debate regarding the ultimate cause of coral loss which centers mainly on the roles played by overexploitation of herbivorous fish and direct coral mortality.

8. Pattern of loss The earliest measurements of Caribbean coral cover taken by scientists date from the middle of the 20th century.

9. A compilation of records shows that Caribbean coral cover has declined since 1977, from an average across the region of approximately 50% to only 10% by 2001

10. This represents an 80% decline in 25 years, which ranks among the fastest rates of loss for any ecosystem in the world. The low coral cover has been maintained since 2001, and there is no evidence of further losses at the regional scale.

11. No one knows what Caribbean coral reefs looked like centuries ago, and hence whether periods of low coral cover have naturally occurred. However, it is possible to get a glimpse of the past by examining of cores taken from ancient reefs.

12. While such paleoecological reconstructions do not reveal the extent of coral cover, they do show which species were present. Cores taken from reefs in Belize, Jamaica and Panama suggest that Caribbean coral assemblages have been dominated by acroporid corals for centuries, if not millennia. The present state of Caribbean coral reefs therefore appears to be a novel condition.

13. A large portion of the regional decline in coral cover can be attributed to the near-disappearance of two coral species, Acropora palmata and Acropora cervicornis. These large, branching corals were formerly extremely abundant on shallow-water reefs, but outbreaks of white-band disease, beginning in the late 1970s, have significantly reduced populations of these corals across the region.

14. Causes of coral loss There are many factors implicated in the loss of corals in the Caribbean. Some, such as pollution and sedimentation arising from deforestation and coastal development, occur at local scales . Others, such as disease outbreaks and thermally induced coral bleaching, can affect large parts of the region at once.

15. There is currently an unresolved debate surrounding the ultimate cause of coral loss. Three main ideas have been proposed.

16. First, coral loss is the result of overfishing. Centuries ago, abundant herbivorous fish kept macroalgae on Caribbean coral reefs in check. As these fish were depleted by fishing, their ecological role was assumed by sea urchins. The mass mortality of the abundant herbivorous sea urchin Diadema antillarum in the early 1980s left few herbivores on Caribbean reefs, releasing algae to overgrow and kill corals.

17. Second, coral loss is due to pollution. Nutrient enrichment from development and agricultural run-off has favored the growth of algae, and caused the subsequent mortality of corals. The fact that coral loss has occurred on remote reefs, far away from human influences, suggests that this cause may not be a general one.

18. Finally, coral loss is due to factors that cause direct coral mortality. These factors include diseases, coral bleaching and storms, all of which have increased in incidence in the past four decades. Although the debate has been polarized into these three distinct positions, it is likely that coral loss at any given location has been caused by one or more of these factors

20. Fortunately, there is now evidence, from various parts of the Caribbean, that reefs that experienced extensive coral loss in the 1980s are now recovering. The recovery of corals on many of these reefs has been associated with the resurgence of Diadema antillarum populations. There is therefore some hope that Caribbean coral reefs can return to their former coral-rich state.

21. Muroaminetting is a dangerous fishing practice that has led to extensive coral deterioration in Southeast Asia. Fishermen use nets that are weighted and decorated with brightly colored plastic strips and pounding devices in order to startle and herd reef fish. The pounding devices are usually large stones on ropes or cement attached to a crane fitted to the fishing vessel. Muroami. (Photo credit: Howard Hall)

22. The weights are lifted and dropped repeatedly along the reef, breaking live coral along the way. In many counties that use this practice, as many as 300 young boys, 10 to 15 years old, are used to set the nets and bang on the coral. The practice was banned in the Philippines in the 1980s, but continues illegally in some places.

23. (From Coral degradation through destructive fishing practices)

24. In the 1980s, rock-hopper trawls were invented; the large tires and rollers that were attached to the bottom of nets allow the nets to roll over any rough surface. Fifty-five percent of cold-water coral in Alaska that was damaged by one pass from a bottom trawl had not recovered a year later. In the Northeast Atlantic, there are scars up to 4 km long on the reefs from bottom trawlers. In Southern Australia, where heavy fishing occurs around corals, 90 percent of the surfaces are now bare rock. Even in the Great Barrier Reef World Heritage Area, seafloor trawling for prawns and scallops is causing localized extinction of some coral species. A report released in 2004 by WWF, IUCN, and the NRDC cited bottom trawling to be the single greatest threat to deep sea environments.