A large bloom of seaweed that followed super-Typhoon Bopha in December 2012 caused a temporary setback in recovery of Palau’s eastern reefs, threatening ecosystem function.

A team of researchers from The University of Queensland’s Marine Spatial Ecology Lab (MSEL) and the Palau International Coral Research Center (PICRC) studied how the bloom affected coral recovery at Bopha-impacted reefs.
The study, published in the international journal Coral Reefs, found that Bopha-impacted reefs with blooms of large red Liagora seaweed had failed recolonisation of baby corals that are essential for rapid reef recovery.
Dr Christopher Doropoulos, lead author and Postdoctoral Fellow from The University of Queensland, said the timing of the seaweed bloom was unfortunate as it occurred during the annual spawning event.
 “The seaweed bloom deflected baby corals in a number of ways,” he said.
“Baby corals are initially found as swimming larvae before they choose their place to attach to the reef and settle for life, a critical step to their survival and the maintenance of coral reefs.
“Seaweeds often produce toxic chemicals to outcompete and defend against other organisms and these chemicals deterred and killed swimming coral larvae.”
Fortunately, the seaweed was gone from affected reefs by April 2013 and Dr Doropoulos says the reefs are well on the road to recovery.  
“Palau’s reefs have multiple spawning events throughout the year and have started to recolonise since the Liagora bloom disappeared,” he said.
“We found that impacted reefs that didn’t have the seaweed after Bopha still had a good supply of baby corals.”
“Given all the evidence, and the protection of surgeonfish and parrotfish, we predict that recovery of the affected reefs should now be in full effect.”
Dr Doropoulos was hosted by PICRC in 2013 during an Australian Endeavour Award Postdoctoral Fellowship. This new study adds to the growing body of joint research involving researchers from MSEL and PICRC and there is much more to come.
Citation: Doropoulos C, Roff G, Zupan M, Nestor V, Isechal AL, Mumby PJ. (2014). Reef-scale failure of coral settlement following typhoon disturbance and macroalgal bloom in Palau, Western Pacific. Coral Reefs. http://dx.doi.org/10.1007/s00338-014-1149-y


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