Reef recovers from bleaching faster than expected


A reef in Australia that suffered catastrophic mass bleaching in 1998 has recovered more quickly than scientists had expected.

Around 80% of the coral cover on Scott Reef was lost to bleaching following an extreme rise in temperatures. The reef is isolated and more than 250km from Western Australia, a fact which had been expected to hinder its recovery as there were no reefs close by to provide it with coral larvae.

However, scientists found that within 12 years the cover and diversity of corals had recovered to levels similar to those seen pre-bleaching, the isolation of of reef allowing surviving corals to rapidly grow and propagate in the absence of human interference.

The long-term study was undertaken by marine biologists from the Australian Institute of Marine Science (AIMS) and the ARC Centre of Excellence for Coral Reef Studies (CoECRS) and published online in the journal Science.

"The initial projections for Scott Reef were not optimistic," says Dr James Gilmour from AIMS, the lead author on the publication, "because, unlike reefs on the Great Barrier Reef, there were few if any reefs nearby capable of supplying new recruits to replenish the lost corals at Scott Reef.

"However, the few small corals that did settle at Scott Reef had excellent rates of survival and growth, whereas on many nearshore reefs high levels of algae and sediment, and poor water quality will often suppress this recovery.

"We know from other studies that the resilience of reefs can be improved by addressing human pressures such as water quality and overfishing. So it is likely that a key factor in the rapid recovery at Scott Reef was the high water clarity and quality in this remote and offshore location.

Dr Andrew Heyward, Principal Research Scientist at AIMS, says: "Previously we’ve tended to factor proximity to other reefs as a key attribute when estimating the resilience of a reef following a major disturbance, but our data suggests that given the right conditions, reefs might do much of the recovery by themselves. This finding could have implications for the management of marine protected areas."

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