Posts Tagged coral reef

Australian media on a mission to make scientists look dodgy Rebecca McLeod Dec 21

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Yesterday 895,000 Australians (and this one Kiwi) woke up to the headline “HOPES FADE IN COPENHAGEN, RISE ON THE REEF” in a national newspaper. As one who is always up for a bit of optimism I began reading… but by the second line my hopes were somewhat dashed: “Scientists ‘crying wolf’ over coral”.

This front page story reported the views of one (I repeat ONE) scientist, Peter Ridd, a physicist from James Cook University, who believes that ecologists and biologists studying the Great Barrier Reef are guilty of exaggerating threats to the reef, such as increased sedimentation, crown of thorns starfish, pollution, and temperature-induced damage called bleaching. Ridd argues that the reef is still in ‘good health’ despite public attention being drawn to these individual threats over recent years, thus affecting the credibility of marine scientists, particularly with respect to current concerns about the susceptibility of coral reefs to climate change.

It seems to me that The Australian has gone out of its way to turn this scientific debate, which is essentially one marine scientist disagreeing with a score of others, into another example of how ‘dodgy scientists’ are conspiring to delude the public into thinking that climate change is a real phenomenon.

A more in depth article further inside the newspaper “How the reef became blue again” does quite a good job of describing recent research findings by scientists at the Australian Institute of Marine Science, regarding the ability of corals to recover from bleaching events caused by increases in water temperature. However, you have to dig really deep to get to what I think is the part that is deserving of the headline:

“Ocean acidification is another matter, however. This lesser-known product of climate change is a greater danger to the reef by Ridd’s assessment. It happens as the ocean absorbs CO2 from the atmosphere, altering its pH value. Although surface sea temperatures are rising fastest in tropical regions, the threat of acidification comes from the higher latitudes, where the colder water takes in CO2 more easily.

The theory is that when atmospheric CO2 reaches between 480ppm and 500ppm, the warmer water lapping coral reefs will cease to be a barrier to acidification: even a small change is thought to spell trouble for calcifying organisms such as corals, making it more difficult for them to make the skeleton structures that in turn build reefs.”

If you would like to find out more about this incredibly scary phenomenon, I posted a rather thought-provoking film on it a couple of months ago. Even Peter Ridd thinks that ocean acidification is the single greatest threat to the Great Barrier Reef – but only those few of the 895,000 that got close to the end of the 2 page article would be aware of this!

Are the public so supersaturated with climate change stories that the media are having to infer scientific controversy to get the attention of the public? Quite possibly. How sad.

A+ for Australian Marine Scientists Rebecca McLeod Dec 04

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The Marine Climate Change Impacts and Adaptation Report Card Australia 2009 has just been released. Hiding behind the long-winded name is an excellent resource – a website-based state-of-knowledge of how climate change is likely to affect Australia’s marine life, with expert opinions from more than 70 marine scientists across the country.

Whilst the majority of the information presented on the website is available in various scientific papers, having it all combined on a common site, and in plain English is a real leap forward in making marine issues accessible to the public. Through many many many many (you get the drift) hours of careful research, scientists from a large range of disciplines have come to conclude that climate change has, is and will continue to affect marine life.

And these implications seem to reach every kind of marine environment there is – from the open ocean to coastal reefs to estuaries. Particularly concerning are stresses upon species that provide a home for marine animals – for example, kelp forests, among which a multitude of fish and invertebrate species live, are very sensitive to changes in seawater temperature, and so are predicted to disappear from southern Australia if seawater temperatures continue to rise.

Kelp forests are predicted to disappear from Tasmania should the sea temperature continue to rise

Kelp forests are predicted to disappear from Tasmania should the sea temperature continue to rise

Meanwhile in more tropical regions, such as the Great Barrier Reef, corals are suffering from multiple climate change related issues. Increased water temperature can stress corals, causing death of the individual anemone-like creatures that come together to form a coral colony. This occurrence is known as “bleaching”, and is becoming increasingly common and severe. A more recently-discovered phenomenon – ocean acidification – has the potential to devastate corals and other organisms that have skeletons made of calcium carbonate. It isn’t pleasant to think about, but if the corals disappear, so too will all of those who live on and amongst them.

Of course, with environmental science, and science in general, it is difficult to “prove” things beyond all doubt. To reflect such uncertainty, the observations, predictions and forecasts are rated with high, medium or low confidence, and I think that this is a really worthwhile addition to the site. Also included are sections on things that aren’t yet known, and require further research.

This site does make for some scary reading, and I wonder whether a section along the lines of “what you can do”, or “alternative pathways” section might lessen the blow. But then, it could be argued that individual efforts from the public would not be enough to stop the processes that are already in motion – what is needed are global-scale changes introduced by world leaders.

In the meantime, marine scientists will keep working to document our rapidly changing marine environments…

How resilient are coral reefs to tsunamis? Rebecca McLeod Nov 24

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The September 29th tsunami waves left widespread destruction across the Pacific nations of Samoa, American Samoa and Tonga, evidenced by devastated villages, and multiple fatalities and injuries. But what about the natural environment? Was there paralleled damage under the sea, on the coral reefs that fringe these islands? Not only is this question of interest from an ecological perspective, but also from a social perspective: communities rely heavily upon these reefs for food, tourism and social wellbeing. As these communities begin to rebuild, and eventually encourage tourists to come back, the state of the coral reefs could be a factor in a tourism market that relies heavily on water-based activities.

The potential for damage to coral reefs following major storm surges and tsunamis is two-fold: the initial force of the waves hitting the reef, and the subsequent delivery of huge amounts of sediment and debris onto the reef as the wave retreats and during rainfall in the following weeks.

Using field tests, scientists at the ARC Centre for Excellence in Coral Reef Studies have demonstrated that the shape of the coral influences how vulnerable it is to damage by large waves. For example, table-topped corals (those with a broad top and attached to the reef by a stalk) are more prone to being overturned by a large wave than those that are mounded or branched. Location matters too, with corals on the front and crest of the reef where the waves break being more prone to damage by large waves than those situated on the top and back sides of the reef.

Arguably the greatest tsunami-associated threat to corals is posed by sediment and debris that is carried from the land as the waves retreat. Sediment can smother and even bury corals, leading to suffocation of the coral polyps. Extensive mechanical damage and scouring can result from debris such as building materials, machinery and cars getting pounded onto the reef.

Initial surveys of coral reefs along the west coast of Thailand following the Boxing Day tsunami in 2004 recorded mass destruction of corals. However, despite these initial concerns, repeat surveys in the following months found that the damage, although severe in small patches, was generally not as bad as first feared. This anomaly was due to much of the coral initially recorded as dead having in fact recovered. On the Island of Banda Aceh at the northern tip of Sumatara, scientists were in a unique position of being able to make before and after comparisons of reef health, as they had surveyed the reefs prior to the tsunami. The research team, led by Dr Andrew Baird at the ARC Centre for Excellence in Coral Reef Studies reported a remarkable resilience of coral communities to the tsunami waves. The damage observed was considerably less than that caused by destructive fishing practices (e.g. dynamite fishing) and coral harvesting, and was also considered to be significantly less than that resulting from hurricanes, due to differences in the distribution of wave energy in the water column.

I am not aware of any similar surveys being carried out in areas affected by the most recent tsunami (if you know of any please tell me!), but these experiences from the 2004 tsunami seem to suggest that the long-term impacts of the tsunami waves on coral reefs may not be all that bad. It seems plausible that those reefs in good health prior to the tsunami may experience a faster recovery than those already suffering from bleaching, grazing crown of thorns starfish, or destructive fishing practises.