Ebonnie Spriggs ABC News 23 Jun 14;
Ningaloo Reef, off Western Australia's Pilbara coast, appears to have escaped relatively unscathed from the impacts of recent flooding, described as a once-in-a-century event.
There had been concerns the reef might be hit by coral bleaching after the floods in April reached Exmouth's major tourism drawcard, when tonnes of silt and sediment, and fresh water washed into the sea.
But the Department of Parks and Wildlife's (DPAW) Arvid Hogstrom says initial research - conducted in collaboration with the CSIRO - has revealed little to no short-term damage.
"There was an expectation that due to the freshwater influx from the flooding event that some of that coral may have suffered coral bleaching as a result and died off," he said.
"But we were very pleased to hear the level of impact from that freshwater event was minimal, and the level of coral bleaching was virtually nil immediately following that flood event.
"The other thing they looked at was direct smothering of corals as a result of all that sediment and silt coming out.
"There was some localised impacts where some corals had been covered by sand and silt and branches and other debris but the level of impact was very small, smaller than we expected so, all in all, we were very happy with that initial outcome."
Just days after the floods, Mr Hogstrom described the waters of the Ningaloo Reef as mud-stained.
He said the waters have since returned to their famous turquoise colour.
"It's actually remarkably good, the water is crystal clear again," he said.
"The lagoons are their magnificent turquoise blue that catches everybody's eye as they drive into the World Heritage area, so it really looks as good as it has ever looked.
"Apart from some sort of immediate changes along the coastline where there are some new alluvial fans and silt fans, the park - both the terrestrial and marine side of it - looks as good as it has ever looked."
Checking mangrove sites and coastline changes
Mr Hogstrom said his understanding is the impacts of flooding should be noticeable very soon after the event.
"The fresh water can kill them [coral] off quite quickly and you will see some rapid changes so we are actually quite confident that there shouldn't be any longer term impacts than what we have already seen," he said.
"But because it's such an unusual event, and potentially a one in 50 to 100 year event, we just want to do the long-term monitoring to make sure we're not missing something."
DPAW will continue to monitor the coral, dune system, mangroves and seagrass.
"What we will be doing now is setting up some longer term monitoring of various sites to make sure the initial results we have seen aren't short term only and there's no long-term impacts of the silt that was in the water or the freshwater that was in the saltwater lagoon systems," Mr Hogstrom said.
"At this stage the mangroves and seagrass are all looking quite good.
"There is a bit of sediment and silt that has been deposited amongst the base of the mangroves, but there doesn't appear to be any die-offs of mangroves at this point in time.
"We are quite confident that it will return to its natural state, but we will be keeping an eye on it."
"We will [also] be assessing percentage coral cover and seeing whether there has been any reduction as a result of this flooding event.
"The other thing we are very interested in looking at is actually an assessment of the coastline itself, so the dune systems and the beaches because obviously there was significant erosion as a result of the flooding.
"We will be looking at those erosion areas to see whether they are returning to the way they were pre-floods or whether they are actually a permanent change and basically the whole coastline may have changed."
Mr Hogstrom says the CSIRO has long-term monitoring sites along the Pilbara coastline, which fortunately include Ningaloo.
"What it allows them to do and [to] pass ... onto us is compare the current state of it following the floods to what it was like beforehand," he said.
"Also they will be able to compare it over the next few years as things change."
Reef resilient to extreme events
Mr Hogstrom says Ningaloo Reef has proven it can cope with these extreme events.
"It's not a man-made event and I guess it is used to it albeit it may only happen only once every 100 years or so but the reef is resilient and seems to have bounced back quite quickly," he said.
A number of camp sites at the Cape Range National Park were shut down as a result of flooding, but the park itself is re-opened.
"Apart from four or five camp sites which we have closed down as a result of the flooding, the rest of the park is open," Mr Hogstrom said.
"All the key areas are all back open to the public and we have got about 125 sites out of about 140 camp sites re-opened to the public so there's plenty of camping available.
"The countryside is looking magnificent, some of the best vegetation, spinifex growth and seeding that I have seen for many many years so I think it'll be a fantastic wildflower season as well."
