Hot seas bleach Ningaloo Reef

Narelle Towie - 

Abnormally hot sea temperatures at Ningaloo Reef are bleaching the area's coral, environmental officers say.

Ocean surface temperatures at the reef have been 3C higher than average since October and peaked at 29C in the past two weeks - the 'trigger level' for bleaching.

The Department of Environment and Conservation detected the patches of bleached corals using satellite imaging.

“By continually monitoring the reef, we can look at changes over time and determine the significance of temperature-induced bleaching events,” DEC marine science leader Chris Simpson said.

Coral bleaching is a phenomenon where algae, which gives coral its colour, is expelled from inside the reef's tissue because of stress, leaving just the white skeleton of the coral behind.

Bleaching events are usually caused by long periods of warm sea surface temperatures but they can also be associated with exceptionally low ocean temperatures, disease or pollution.

“Initial reports related to sea surface temperature indicate that water temperatures in the Ningaloo area have been elevated to levels that may cause bleaching in some coral species,” Dr Simpson said.

“These temperatures are not expected to drop for at least two to three weeks because of the cyclonic activity over the Pilbara and Kimberley restricting flushing and causing heating of lagoon waters."

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