Months after scientists warned it is at greater risk than ever, the Great Barrier Reef is facing a new challenge: dirty water.

Run-off from the recent floods in Australia is spreading from the coast with the potential to reach the fragile reef.

The floodwater is thick with sediment from the shore and scientists fear that this may block out the sun, preventing photosynthesis in the algae the coral relies on to survive.

Dr Frederieke Koon from the Australian Institute of Marine Science told the BBC the floodwater contains nutrients that have also boosted algae growth in some areas, turning the water into “a thick blanket of green”.

It is also feared the floodwater could contain pesticides that could prove extremely damaging to the reef.

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Due to a lack of wind, the floodwater isn’t dispersing.

Dr Koon said “a bit of wind and wave action can break the plumes up quite quickly, but we have literally had no wind so they’re just sitting there hanging”.