A coral reef 300 km northwest of Cape Leveque in Western Australia that was decimated by a global bleaching event in 1998 has healed itself remarkably in just 12 years, according to a news release detailing a joint study of the reef by Australian Institute of Marine Science (AIMS) and the ARC Centre of Excellence for Coral Reef Studies (CoECRS).
The study questions the long held notion that isolated reefs are more vulnerable to such events and that these reefs are dependent upon other reefs to recolonize.
According to the study, Scott Reef, a remote coral reef located in the Indian Ocean that is Australia’s largest oceanic reef system found that the reef system’s isolation in the Indian Ocean, away from human interaction such as the overfishing of herbivorous fish and urban runoff enabled the coral reef to regrow fairly rapidly and without human intervention. When the bleaching event occurred, scientists say more than 80 percent of the reef’s coral cover was lost, with a bleak prospect of the reef regrowing. The scientists calculated that with the low number of surviving coral species on the reef, it would take decades for the reef to recover to its former condition. However, the reef not only recovered in about 12 years, the diversity of coral species found on the reef prior to bleaching remained about the same.
“The initial projections for Scott Reef were not optimistic,” Dr. James Gilmour from AIMS, the lead author on the publication, said in a statement. “. . . 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 near shore reefs high levels of algae and sediment, and poor water quality will often suppress this recovery.
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“We know from other studies that the resilience of reefs can be improved by addressing human pressures such as water quality and overfishing,” Gilmour said. “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.”
The scientists reiterated that human events such as overfishing, bad water quality, sedimentation and climate change will likely cause affected reefs to never fully recover from such events, especially when these activities are ongoing and pervasive.
The paper “Recovery of an isolated coral reef system following severe disturbance”, by J. P. Gilmour, L. D. Smith, A. J. Heyward, A. H. Baird and M. S. Pratchett appeared online in the journal Science April 5, 2013.