Donovan, M.

Outbreaks of Acropora and Diadema diseases in the 1970s and early 1980s, overpopulation in the form of too many tourists, and overfishing are the three best predictors of the decline in Caribbean coral cover over the past 30 or more years based on the data available. Coastal pollution is undoubtedly increasingly significant but there are still too little data to tell. Increasingly warming seas pose an ominous threat but so far extreme heating events have had only localized effects and could not have been responsible for the greatest losses of Caribbean corals that had occurred throughout most of the wider Caribbean region by the early to mid 1990s.
In summary, the degradation of Caribbean reefs has unfolded in three distinct phases:
1. Massive losses of Acropora since the mid 1970s to early 1980s due to WBD. These losses are unrelated to any obvious global environmental change and may have been due to introduced pathogens associated with enormous increases in ballast water discharge from bulk carrier shipping since the 1960s.
2. Very large increase in macroalgal cover and decrease in coral cover at most overfished locations following the 1983 mass mortality of Diadema due to an unidentified and probably exotic pathogen. The phase shift in coral to macroalgal dominance reached a peak at most locations by the mid 1990s and has persisted throughout most of the Caribbean for 25 years. Numerous experiments provide a link between macroalgal increase and coral decline. Macroalgae reduce coral recruitment and growth, are commonly toxic, and can induce coral disease.

3. Continuation of the patterns established in Phase 2 exacerbated by even greater overfishing, coastal pollution, explosions in tourism, and extreme warming events that in combination have been particularly severe in the northeastern Caribbean and Florida Keys where extreme bleaching followed by outbreaks of coral disease have caused the greatest declines.
 
In: Status and Trends of Caribbean Coral Reefs: 1970 - 2012. Jackson, J.B.C., Donovan, M.K., Cramer, K.L. Lam, W.. - Washington : Global Reef Monitoring Network, 2014 - p. 55 - 154.
Retreived from http://www.wageningenur.nl on April13, 2015

The International Union for the Conservation of Nature (IUCN) assumed leadership of the Global Coral Reef Monitoring Network (GCRMN) in 2010 with three primary objectives:

1. Strengthen scientific understanding of the status and trends of coral reef ecosystems at different places around the world.
2. Improve communication among the scattered members of the Network.
3. Make reef data publicly available online in a timely fashion.

The purpose of our new scientific endeavor is to establish quantitatively rigorous baselines for earlier reef conditions and to document the extent to which different reefs have varyingly declined from a relatively more pristine to degraded state. This variability is the key to understanding why some reefs have much more abundant corals than others; knowledge that is essential for preserving and restoring coral reefs and their ecosystem services in the foreseeable future.

Because of the enormity of the task, we plan to focus on separate biogeographic regions in a stepwise fashion, and then combine all of the results for a global synthesis by 2016. We have begun in tropical America because this is the region with which we are most familiar and to refine our methods of analysis before moving on to other regions. This report describes the results of our very preliminary Caribbean analysis. It will be followed closely by an assessment of the tropical eastern Pacific. This work will be completed in 2012.

The three major components of the scientific effort are to:

1. Document quantitatively the status and trends for all routinely monitored components of coral reef ecosystems, including reef corals, macroalgae, other sessile benthos, sea urchins, and fishes based on data provided by individual researchers as well as the scientific literature, monitoring programs, and reports;
2. Conduct workshops to bring together people who collected the data to directly involve them in data analysis and synthesis; 
3. Interpret variations in status and trends in relation to independent environmental, management, and socioeconomic data to better understand what are the primary natural and anthropogenic factors driving coral reef decline and how they may be more effectively alleviated,

We assembled 36 scientists from 18 countries and territories to assess status and trends of Caribbean reefs at our first workshop held at the Smithsonian Tropical Research Institute (STRI) in the Republic of Panama 29 April to 5 May, 2012. Discussions were based upon initial exploratory analyses of approximately half the 253 data sets obtained so far from 29 countries. Trajectories of status and trends were constructed for reefs from seven countries with additional data for reef fish.

Three general points are clearly evident from these preliminary analyses:

1. The routine analytical procedure of ecological change on reefs that combines data from distant sites obscures important ecological differences among geographic locations and habitats of crucial importance for policy and management.
2. Some Caribbean reef ecosystems are relatively intact compared to average conditions in the region. For example, many reefs in the Netherlands Antilles and Cayman Islands have 30 % or more live coral cover, little macroalgae, and a moderate (albeit strongly depleted) abundance of fish. In contrast, reefs in Jamaica and the US Virgin Islands have well below 10% live coral cover, abundant macroalgae, and virtually no fish larger than a few cm.
3. The causes of these regional differences in reef conditions are not well understood beyond the obvious role of human exploitation and disturbance. Caribbean reefs with the highest surviving coral cover and least macroalgae tend to be characterized by little land-based pollution, some degree of fisheries regulations and enforcement, moderate economic prosperity, and lower frequency of hurricanes, coral bleaching, and disease. Unraveling the potential interactive role of these and other factors is a major goal of our study once all the necessary data are available.

More extensive and detailed results will be presented in a draft Caribbean Synthesis Report in December 2012, to be published and made available online by March 2013. We also plan to follow up with a second Caribbean workshop immediately preceding the 2013 ICRI Meeting in Belize to bring together members of the different GCRMN Caribbean nodes to explore ways the results of the scientific analysis can be used to improve the effectiveness of Caribbean reef monitoring and policy.