Flood flow-on to Barrier Reef
The floods that have devastated large parts of Queensland, northern NSW, and Victoria will have long-lasting effects. For the people who have lost loved ones, lost homes, or suffered dislocation and damage the impact may continue for months into years. Whole towns will take a long while to return to their pre-flood state, if they ever do. In addition to all of this the World Heritage listed Great Barrier Reef is also likely to suffer.
As a result of the flooding in Queensland a surge of polluted water is emanating from the mouths of rivers and is impacting the ocean surrounding the reef. Researchers from James Cook University estimate that as of mid-January already eleven per cent of the ocean surface of the Barrier Reef, which runs for 2000 kilometres along the Queensland coast, has been covered by outflows from the Burnett Mary and Fitzroy rivers. This is bad news for the coral that makes up the reef.
The flood water is freshwater, and fresh water kills coral meaning that the shallow reefs closer to shore are under major threat. Additionally, the flood waters are rich in nutrients and pesticides. As this foggy water plume spreads it will block out light from parts of the reef in deeper water. This will prevent photosynthesis but provide prime conditions for coral competitors like microalgae. It is the algae growth that can produce a time-bomb that could be the reefâ€™s biggest threat.
The nutrients in the flood water cause blooms of the microalgae and in turn these microlarvae provide a perfect food source for the reefâ€™s nemesis; the crown of thorns starfish.
Each female crown of thorns starfish produces 60 million eggs per year. A nutrient rich resource such as the flood waters and associated algae will promote a population boom. Since the starfish take three years to mature they could in that time feasibly spread throughout the entire reef.
Reefs take around 25 years to recover from a â€œstarfish eventâ€ and the scarey thought is that at the moment the Great Barrier Reef is being struck by such an event every fifteen years. The maths is not hard to interpret. Marine ecologists will feverishly be doing all that they can to support the vulnerable coral in the coming years.