Up to half Great Barrier Reef reefs damaged by Cyclone Debbie



One of the planet’s most stunning natural phenomenons has begun in earnest as one of the Great Barrier Reef’s finest breeding grounds has begun to restore its natural balance.

Biologists are flying over the Great Barrier Reef to gather data, but imagery of the destruction appears to have caught up to observations this week, revealing how devastating the process has been since Cyclone Debbie inflicted unprecedented damage in March.

With more than 10% of reefs affected, it appears from satellite images recorded on Thursday and Friday that 50% of reefs have lost 50% of their fish biomass, which is critical for a healthy reef.

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“Half the food for all the fish that live here is born from spawning, so we are thinking that that large proportion is impacted as well,” Kimberly Hume, Australia’s chief scientist, told Guardian Australia.

Numerous larvae, small fish and shellfish are so rich in nutrition they can survive for months or even years in the water, fertilised by water from the ocean and released from the bed of the Great Barrier Reef.

If they form huge communities, they have a multiplying effect, staving off the spread of disease and blight by making the reef healthier than it would otherwise be.

Many of the larvae and communities observed in this week’s photographs are believed to be dead. A crevice in the sea bed where many of them form will remain as permanent monuments to the destruction.

Crabs move in through nesting areas in Gladstone in Queensland after storms damaged the coastline. Photograph: Ben Quilty/Guardian Australia

Hume said there is no question that heavy sediment and other pollutants from the build-up of the same rubbish in stormwater run-off is a major driver of the ecosystem change.

In 2015-16, more than a million kilograms of black powder and garbage were dumped into the ocean and many more kilograms deposited into the reef from landing areas and ports.

The extent of the progress made by male and female fish is impossible to assess. Hume said satellite imagery could provide results by the end of next week.

The state of the Great Barrier Reef will be an important issue as the federal and Queensland governments rush to a new round of negotiations with the Queensland government over the management of the reef.

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