Not long after Australian wildlife officials raised their response to the coral bleaching along the Great Barrier Reef to highest level, scientists are now warning that the reef - which is considered to be the largest living structure on the planet at more than a thousand miles long - is experiencing some of the worst coral bleaching in recorded history in some of its regions.
"We're seeing very severe bleaching in the northern part of the reef," said Terry Hughes, head of the Australian Research Council (ARC) Centre of Excellence for Coral Reef Studies. "And I think that just highlights how precarious the situation has become, whereby severe El Niño events, which happen every few years, are enough to trigger a bleaching event. And it wasn't always like that."
The findings were gathered during an aerial survey of 520 reefs in Cairns, Australia, which covered the northern part of the reef and was what Hughes described as the "saddest research trip" of his life.
"We found only four reefs out of 520 that weren't bleached to some extent, and more than 95 percent of the reefs were in the top two most severe bleaching categories," Hughes said. These results are staggering, especially in comparison to the previous bleaching event in 2002 that only led to 18 percent of reefs falling into these two categories.
Hughes claims the "northern barrier reef is much more severely bleached than ever before."
Bleaching stems from warm ocean temperatures that stress coral, leading to the loss of the algae that live with them and provide them with energy through the process of photosynthesis. Without these algae, the corals "bleach" and, in some situations, eventually die if the stresses are prolonged.
Despite the known negative effects of coral bleaching, it is not the same as mortality and it is not known how many corals have died from the process. However, scientists are quite sure that the phenomenon will have a "long-term damaging impact on the northern reefs."
"This is not like any global bleaching event we've seen in the past," said Mark Eakin, a corals expert with the National Oceanic and Atmospheric Administration (NOAA). "In the past, these events have been a one-year event. What happened in '98, happened in '98. It was all within the scope of less than 12 months."
