Bleaching occurs when coral is starved of nutrients, stripping it of its colour. (Source: Australian Institute of Marine Science)


Predictions of severe coral bleaching events mobilise marine scientists to monitor the oceans

Scientists across Australia are preparing for what could be the most damaging coral bleaching event (or marine heat wave) in history.

Rising sea temperatures, and this year's strong El Niño event, could combine to damage delicate reef systems on both sides of the continent.

The IMOS network of marine observation facilities, including fixed temperature monitors and mobile devices such as Slocum gliders will be employed to monitor ocean conditions to inform scientists of changes and therefore risk of coral bleaching.

Leader of the IMOS National Mooring Network, Mr Craig Steinberg, notes that past El Niños have been associated with extensive bleaching globally, and is concerned about the consequences of this summer's weather patterns on Australia’s reef systems.

“We are gearing up on the east and west coasts for a potential mass coral bleaching event this summer.

“Long-term observations are needed to understand change and variability so we are positioning for the IMOS backbone of moorings, sensor networks, satellite receiver and gliders to be a part of the monitoring effort,” said Steinberg.

Bleaching occurs when stress, such as heat, causes algae to be ejected from the coral in which it lives. The loss of the symbiotic algae strips the coral of its colour, and starves it of nutrients.

This results in a loss of habitat for fish, with a risk of effects on other dependent species, fishing industries and tourism. Seabirds have experienced failed breeding seasons due to the inability to source food locally. Both west and east coasts of Australia are considered at risk of coral bleaching.

“At the moment there is a warming off Joseph Bonaparte Gulf expected to peak in January and then reside, then the Great Barrier Reef is expected to 'ramp up' the warming in the new year,” said Steinberg.

Coral can recover from bleaching if the heat wave doesn’t persist for too long, but it takes many years for the corals to recover. Analyses of reefs in north-western Australia following a severe bleaching event, show that reefs can recover, but it can take up to 10 years for this to occur.

Scientists fear that over the next decade, warming waters will increase the number of bleaching events and push the reefs to breaking point. They believe it is important to document how widespread and severe the bleaching is, and also to learn more about the physical conditions which have caused the bleaching events.

Marine scientists from several different institutions and agencies held a planning workshop in Perth, Western Australia, last week and today the Great Barrier Reef Marine Park Authority held a pre-summer reef health workshop.


Parts of this article were sourced from scientists planning for 'one of the worst' coral bleaching events, 26 November 2015

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