Australia's Floods Endanger An Already Stressed Great Barrier Reef

great barrier reef image

Photo by eutrophication&hypoxia; via Flickr Creative Commons

We've been hearing about the intense flooding in Australia for weeks now, but a lesser known side effect is the impact those floods are having on the Great Barrier Reef. Adding to the stresses already faced by the coral reef are both the
cyclone itself and all of the pollutants washed from shore.Discovery News reports that, "While the coastlines off of Whitsundays, Port Douglas, and Cairns are again open for tourism, the destructive winds tore through approximately 13 percent of the 1,400 mile-long (2,300 km) Marine Park

"'Expected damage will include smashed coral beds, movements of coral boulders, sand and rubble and major disturbance to seagrass beds,' announced the Great Barrier Reef Marine Park Authority in a statement following Yasi's category 5 cyclone strike on Feb. 5, 2011. "

However, Huffington Post reports that so far, only small portions of the reef will likely show damage from the muddy fresh water washed into the reef.

"Floodwater can hurt reefs in many ways," reports HuffPo. "Coral becomes stressed when the level of salt in the water drops. The high concentration of soil nutrients in floodwater provides food for coral competitors such as certain types of algae. Sediment saps coral of energy by blocking the light it needs to nourish itself, and pesticides in the water can kill the coral outright."

The corals in the Great Barrier Reef have been showing a come-back after years of abuse thanks to efforts such as creation of marine protected areas that minimize stress factors. The reef has to deal with the lingering impacts of overfishing, pollution, and also rising ocean temperatures and changing pH balances. But no marine protected area can keep corals safe from a rush of fresh water like that coming in after the cyclone and heavy rains of the last few months.

Luckily, Nick Graham, a senior research fellow at Queensland's James Cook University, believes that the damage probably won't be as bad as some scientists fear, noting that many parts of the reef close to shore have adapted to floodwaters. While the corals affected by the floods might bounce back, it'd be best if they didn't experience another rush of freshwater, especially that coming from bloated rivers carrying fertilizers from agricultural land and sediments.

As Discovery News notes, even if only part of a reef is hit by a storm or damaged by floodwater, the corals are connected.

"They're not all completely isolated and separate, there is this communication between them," marine geologist Michael Field of the U. S. Geological Survey and project chief for the Pacific Coral Reef Project told Discovery News, in reference to the larvae coral spawn that can travel hundreds of miles before settling onto a reef.

That's part of why it takes a decade or more for a reef to recover, and why isolated damage is still a significant concern.

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