Coral Bleaching Threat Increasing in Western Atlantic and Pacific OceansNewsroom
Unusually warm ocean temperatures are creating conditions that threaten to kill coral across the equatorial Pacific, north Pacific and western Atlantic oceans, the National Oceanic and Atmospheric Administration said Monday.
As aberrantly warm ocean temperatures cover the north Pacific, equatorial Pacific, and western Atlantic oceans, NOAA scientists expect greater bleaching of corals on Northern Hemisphere reefs through October, potentially leading to the death of corals over a wide area and affecting the long-term supply of fish and shellfish.
While corals can recover from mild bleaching, severe or long-term bleaching kills corals. Even if corals recover, they are more susceptible to disease. Once corals die, it usually takes decades for the reef to recover — but recovery is only possible if the reefs are undisturbed. After corals die, reefs degrade and the structures corals build are eroded away, providing less shoreline protection and less habitat for fish and shellfish.
“The bleaching that started in June 2014 has been really bad for corals in the western Pacific,” said Mark Eakin, NOAA Coral Reef Watch coordinator. “We are worried that bleaching will spread to the western Atlantic and again into Hawaii.”
Earlier this year, NOAA’s Coral Reef Watch four-month Coral Bleaching Outlook accurately predicted coral bleaching in the South Pacific, including the Solomon Islands, Papua New Guinea, Nauru, Fiji, and American Samoa. It also recently predicted the coral bleaching in the Indian Ocean, including the British Indian Ocean Territory and the Maldives.
Coral bleaching occurs when corals are stressed by changes in environmental conditions such as temperature, light or nutrients. The coral expels the symbiotic algae living in its tissue, causing the tissue to turn white or pale. Without the algae, the coral loses its major source of food and is more susceptible to disease. Scientists note, however, that only high temperatures can cause bleaching over wide areas like those seen since 2014.
Coral can recover from mild bleaching, but two consecutive years of bleaching could cause severe damage, scientists said.
“Many healthy, resilient coral reefs can withstand bleaching as long as they have time to recover,” Eakin said. “However, when you have repeated bleaching on a reef within a short period of time, it’s very hard for the corals to recover and survive.”
In 2014, Kaneohe Bay on Oahu’s east side suffered the most serious bleaching in the state, which is home to 15 percent of all coral under U.S. jurisdiction. Seventy-five percent of the dominant coral species there lost some color or turned completely white.
Coral reefs are a critical part of the ecosystem, and their health is vital to the ocean environment. Coral cover just one-tenth of the ocean floor, but they are home to 25 percent of known marine species. Some fish eat coral, and others hide from predators in them. Some species use coral as nursery grounds. Some types of shark will frequent coral reefs.
The NOAA Coral Reef Watch program’s satellite data provide current reef environmental conditions to quickly identify areas at risk for coral bleaching, while its climate model-based outlooks provide managers with information on potential bleaching months in advance. The Coral Reef Watch mission is to utilize remote sensing and in situ tools for near-real-time and long term monitoring, modeling and reporting of physical environmental conditions of coral reef ecosystems.
The four-month Coral Bleaching Outlooks, based on NOAA’s operational Climate Forecast System, use NOAA’s vast collection of environmental data to provide resource managers and the general public with the necessary tools to help reduce effects of climate change and other environmental and human caused stressors.
For more information on coral bleaching and these products, visit Coral Reef Watch.
(Story courtesy of NOAA.)