Damaged Caribbean reefs under attack
Rhett A. Butler, mongabay.com
April 10, 2006
After experiencing one of the most devastating coral bleaching events on record during September and October of 2005, reefs in the Caribbean are under attack from deadly diseases according to Reuters.
According to scientists in Puerto Rico, bleaching was both widespread and intense with colonies representing 42 species completely white in many reefs. Surveys show 85 to 95 percent of coral colonies were bleached in some areas, while reefs in Grenada suffered close to 70 percent bleaching in some areas. Reefs in the British and American Virgin Islands were affected to a lesser extent.
Coral bleaching is associated with a variety of physiological stresses, the most important of which is elevated sea surface temperatures. Bleaching causes coral to expel symbiotic zooxanthellae algae living in their tissues -- algae that provide corals with nourishment. Losing their algae leaves coral tissues devoid of color, and thus appearing to be bleached. Corals can recover from short-term bleaching, but prolonged bleaching (over a week) can cause irreversible damage and subsequent death.
Presently Caribbean reefs are suffering from "black band disease, white plague and other ailments" according to a Reuters article which says that researchers from the National Park Service and NOAA are unsure of the extent of the disease outbreak.
Black band disease, associated with several species of cyanobacteria, is characterized by the degradation of coral tissue which causes coral to blacken with the formation of dense white patches of filaments. These disease is not to afflict 42 species of coral worldwide.
Bleaching events leave coral more susceptible to such infections and scientists are concerned that higher sea temperatures could contribute the ever greater reef die-offs in the future.
Caribbean reefs. Image by R. Butler
Scientists have recently warned that the world's coral reefs face a grim future should global temperatures and atmospheric concentrations of carbon dioxide continue to rise. Higher ocean temperatures will produce increasingly severe bleaching events, while elevated levels of carbon dioxide could further acidify the world's seas.
NOAA satellite image for larger view of the regions of high thermal stress as of Oct. 25, 2005, from NOAA's Degree Heating Week (DHW) satellite-based product that accumulates high temperature events. Image courtesy of NOAA
Ove Hoegh-Guldberg, head of the University of Queensland's Centre for Marine Studies, believes that Australia's Great Barrier Reef -- the world's largest reef -- could lose 95 percent of its living coral by 2050 should ocean temperatures increase by the 1.5 degrees Celsius projected by climate scientists.
Coral reefs decimated by 2050, Great Barrier Reef's coral 95% dead November 17, 2005
Australia's Great Barrier Reef could lose 95 percent of its living coral by 2050 should ocean temperatures increase by the 1.5 degrees Celsius projected by climate scientists. The startling and controversial prediction, made last year in a report commissioned by the World Worldwide Fund for Nature and the Queensland government, is just one of the dire scenarios forecast for reefs in the near future. The degradation and possible disappearance of these ecosystems would have profound socioeconomic ramifications as well as ecological impacts.
Pacific Ocean getting warmer and more acidic March 31, 2006
The Pacific Ocean is getting warmer and more acidic, while the amount of oxygen is decreasing, due to increased absorption of atmospheric carbon dioxide say scientists from the National Oceanic and Atmospheric Administration's Pacific Marine Environmental Laboratory and the University of Washington.
Climate change threatens coldwater reefs April 3, 2006
Corals don't only occur in warm, sun-drenched, tropical seas; some species are found at depths of three miles or more in cold, dark waters throughout the world's oceans. Some cold-water coral reefs are home to more than 1,300 species of animals, a diversity rivaling some better known tropical coral reefs. Until now, scientists believed bottom trawling — a commercial fishing method in which vessels drag large, heavily weighted nets across the bottom — to be the greatest threat to cold-water corals.
This article used media materials provided by NOAA, NASA, and Reuters in addition to previously released information from mongabay.com.