Outflow From Massive Queensland Flooding A New Bleaching Threat To GBR; May Also Smother Seagrass
Freshwater bleaching of corals could occur this year as a result of flood waters from Queensland’s overflowing rivers pouring into the Great Barrier Reef, the marine park authority has warned. The Great Barrier Reef Marine Park Authority told Senate estimates hearings in Canberra on Monday that there is a chance corals hit by mass bleaching in 2016 or 2017 could be damaged again by one of several impacts from the flooding disaster.
Bruce Elliot, the authority’s acting chief executive, said scientists were out monitoring flood plumes on the reef and it was possible that freshwater bleaching could affect inshore reefs. The discharge of flood waters into the reef could also smother seagrass meadows, which poses a threat to animals such as dugongs and turtles that rely on seagrass as a primary food source.
It has led to deaths of animals after past disasters, such as cyclone Yasi in 2011. “This event has not been without its ramifications for the Great Barrier Reef,” Elliot said. “There has been major to moderate flooding of the rivers from the Daintree to the Mackay regions.” He said it could be weeks or months before authorities had a full picture of the natural disaster’s effect on the marine park. David Wachenfeld, the authority’s chief scientist, told the hearing there were “extensive” flood plumes on the reef and that unusual wind conditions were carrying them further east and offshore than would normally be expected.
Scientists from James Cook University and the Australian Institute of Marine Science were monitoring the spatial extent of the plumes and their chemical content, he said. Wachenfeld said scientists had already detected some areas on the reef where the water salinity had dropped to almost half its usual level because of the flooding. This causes stress for corals and other marine life used to a saline environment, and freshwater bleaching of corals can result.
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https://www.theguardian.com/environment/2019/feb/18/great-barrier-reef-coral-at-risk-of-bleaching-from-queensland-flood-waters
