July 2, 2014
Long-Term Research Foretells Reversal Of Caribbean Coral Decline
Gerard LeBlond for redOrbit.com - Your Universe Online
Within the next 20 years most of the Caribbean corals could be gone, according to a report by the Global Coral Reef Monitoring Network (GCRMN), the International Union for Conservation of Nature (IUCN) and the United Nations Environment Program (UNEP). Due to the loss of grazers, there is only about one-sixth of the coral cover left in the region.
The report covers research from 1970 to 2012 by 90 experts over a three-year study period. It is the most detailed and comprehensive study of its kind to date. The team analyzed more than 35,000 surveys from 90 Caribbean locations since 1970. They included the study of corals, seaweeds, grazing sea urchins and other fish inhabiting the regions.
According to the report, "Status and Trends of Caribbean Coral Reefs: 1970-2012," Caribbean corals have declined more than 50 percent since the 1970s. However, researchers believe that by increasing the parrotfish population, improving management of other species in the area, protecting the region from overfishing, and reducing coastal pollution, this trend of declining coral can be reversed and it will become more resilient to climate change.
“The rate at which the Caribbean corals have been declining is truly alarming. But this study brings some very encouraging news: the fate of Caribbean corals is not beyond our control and there are some very concrete steps that we can take to help them recover,” says Carl Gustaf Lundin, Director of IUCN's Global Marine and Polar Program.
The main cause of coral decline was long thought to be climate change. Although it does pose a potential threat with coral bleaching and causing the oceans to become more acidic, the reports reveals that the main cause has been the loss of parrotfish and sea urchin to the region. These two species are the major grazers in the Caribbean. With an unidentified disease affecting the sea urchins in 1983, and overfishing of the parrotfish to the point of becoming virtually extinct in some areas, this has contributed greatly to the decline of coral.
As the population of these two species declined, the algae population that they feed on increased and smothered the coral reefs causing them to die.
“Even if we could somehow make climate change disappear tomorrow, these reefs would continue their decline. We must immediately address the grazing problem for the reefs to stand any chance of surviving future climate shifts,” says Jeremy Jackson, lead author of the report and IUCN's senior advisor on coral reefs.
To support the idea that the main cause in the decline of coral is from loss of grazing species, the report states that in the areas where there is an abundance of parrotfish, the coral is among the healthiest in the region. The areas that have banned or restricted the taking of parrotfish include the US Flower Garden Banks National Marine Sanctuary in the northern Gulf of Mexico, Bermuda and Bonaire.
“Barbuda is about to ban all catches of parrotfish and grazing sea urchins, and set aside one-third of its coastal waters as marine reserves. This is the kind of aggressive management that needs to be replicated regionally if we are going to increase the resilience of Caribbean reefs,” says Ayana Johnson of the Waitt Institute's Blue Halo Initiative in collaboration with Barbuda in developing a new management proposal.
The Caribbean holds nine percent of the world’s coral reefs, encompassing 38 countries and is a vital part of the region’s economy. Over $38 billion is taken in annually through tourism and fisheries, with hundreds of billions from other services and goods that over 43 million people depend on.
“The decline in corals started long before climate change began to affect reefs. This report confirms that vigorous populations of grazing parrotfish are a common attribute of the healthiest Caribbean coral reefs. These 'resilient reefs' have strong local protections that are strictly enforced and double or triple the average coral cover of the 14% seen throughout the Caribbean,” says Terry Hughes, author of the 1994 study that predicted the current problems due to parrotfish removal.
“Parrotfish populations are crucial to the very survival of coral reefs, but are being destroyed despite their enormous ecological and economic value. We urge Caribbean nations to work together and respond to the Caribbean coral reef crisis through joint actions, including protecting parrotfish under the Protocol on specially protected areas and wildlife of the Cartagena Convention,” says Jerker Tamelander, head of the UNEP coral reef unit.