Report: Coral bleaching hits record level

Coral bleaching occurs when corals are physiologically stressed by a rise in sea surface temperature and they lose the symbiotic algae which provide them with color and nutrition

May 19, 1999
Web posted at: 4:00 PM EDT

Global warming has been linked to an unprecedented episode of coral bleaching in 1998, according to recent statements issued by the U.S. Department of State and the International Society for Reef Studies.

"Trends of the past century suggest that coral bleaching events may become more frequent and severe as the climate continues to warm, exposing coral reefs to an increasingly hostile environment," according to the Department of State's statement issued March 5.

In 1998, a year recorded by several government and non-government organizations as the warmest year on record, coral reefs around the world suffered the most extensive and severe bleaching and subsequent mortality in modern record.

Coral bleaching occurs when corals are physiologically stressed by a rise in sea surface temperature and they lose the symbiotic algae, which provide them with color and nutrition. Coral reefs can survive if the bleaching episode is brief, but if prolonged, they die.

Coral reefs are considered to be one of the most productive ecosystems on Earth, comparable in biodiversity to the rain forests in the Amazon basin. They provide habitat for 25 percent of all marine species and protect coastal areas from storm damage, erosion and flooding by intense wave action.

According to the State Department, the extent of the damage to corals in 1998 was so great that "even under the best of conditions, many of these coral reef ecosystems will need decades to recover."

"Once the reef is reduced to rubble, fish and other marine organisms are no longer supported," said the State Department said. "Local human populations are thus placed at risk. Over time fisheries stocks are greatly diminished, shoreline erosion increases and the tourist industry is likely to suffer."

The International Society for Reef Studies, an organization dedicated to the dissemination of scientific knowledge about coral reefs, noted that there is much scientific debate about the cause of global warming.

However, "should seawater temperatures rise, either as a result of greenhouse gas emissions or natural variability in the ocean/atmosphere system, then we might expect the incidence and severity of coral bleaching to increase yet further in the future with the possibility of substantial changes to the coral reef community structure," the society said in its statement.

The Department of State said that to minimize this stress to the tropical marine ecosystem humans need to:

• stabilize and reduce greenhouse gas emissions;
• preserve the physical integrity of the marine environment;
• and reduce sediment, chemical and solid waste contamination of marine waters.

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