Black band disease hits Great Barrier Reef

Posted on May 10, 2009 by ovehblog

A recent article in the ABC news tells of the seasonal dynamics of ‘black band disease’ affecting plating corals on the inshore great barrier reef. Yui Sato, the lead author of the journal article painstakingly documented 485 coral colonies across an almost 3 year time period. Interestingly, the results seem to point as light as a driving factor of black band disease progression in infected corals – click here to read the full article from the Proceedings of the Royal Society.

ABC News, 6th May 2009

An epizootic – the wildlife equivalent of a human epidemic – of black band disease has appeared in the Great Barrier Reef, say Australian researchers.

Scientists, who have been monitoring the progress of the disease, say this is the first time an epizootic of this type has been documented in Australian waters.

Black band disease has decimated coral populations in the Caribbean and researchers are concerned it could spread here.

Marine biologist Yui Sato of James Cook University in Townsville and colleagues report their findings in the latest issue of Proceedings of the Royal Society of Biology.

Sato, who is a research student with the ARC Centre of Excellence for Coral Reef Studies, says the black band disease flourishes in warm seawater, killing coral as it eats through tissue, exposing the fragile skeleton.

He is concerned that predicted warmer ocean conditions caused by global warming will lead to longer outbreaks and faster tissue loss. (Read more)

Where have all the big fish gone? Part II: A case study from the Florida Keys

Posted on May 7, 2009 by ovehblog

Following on from two great posts by John and Albert on Carribean reef fish decline and coral collapse, I thought it’d be worth posting these visually stunning images from a recent publication by Loren McClenechan, titled “Documenting Loss of Large Trophy Fish from the Florida Keys with Historical Photographs“. Through analysis of historical photographs in the Florida Keys, Loren managed to piece together a convicing history of recreational fishing trends over the past half century. Large fish really were more abundant in bygone days: the average fish size caught in 2007 was a tiny 2.3kg, compared with 19.9kg in 1957, and that the average length of sharks declined by more than 50% in the same period. In this case though, a picture really is worth a thousand words.

1957

Early 1980's

2007

Continue reading →

Coral “can’t escape the heat”

Posted on May 7, 2009 by ovehblog

picture-379 ARC CoE, 7th May 2009

The world’s corals cannot escape the inevitable impact on them caused by humanity’s carbon emissions.

The warning comes from the eminent scientist who has used coral from the Great Barrier Reef to reveal disturbing changes in the chemistry of the world’s oceans due to human activity.

Professor Malcolm McCulloch, a geochemist with the ARC Centre of Excellence for Coral Reef Studies and Australian National University today receives Australia’s top honour for earth sciences, the Australian Academy of Science’s Jaeger Medal.

“Coral can’t escape the heat,” he says. “Besides the effects of global warming, corals will not be able to avoid the acidification of the oceans, which is a simple and direct consequence of humanity’s interference in the atmosphere. About 40 per cent of the CO2 we release dissolves into the oceans, turning them more acidic.”

Analysis of corals taken from the sea off Cairns revealed an increase in acidity of as much as 0.3 pH units since the start of the industrial age, with most of it occurring in the last 50 years, he explains. If seawater acidifies only a few tenths of pH units further many corals, diatoms and shellfish will be unable to form their skeletons and shells, posing the risk of major extinctions and a threat to marine food chains.

“It’s getting to the point where, besides reducing our carbon emissions humanity is probably going to have to find large-scale ways of actually removing carbon from the atmosphere,” Prof. McCulloch says.

Of the currently raging political debate over carbon trading he states simply “Whatever policy Australia adopts, the outcome must be to reduce our carbon emissions. While they are small in global terms, if we take no action then big emitters like China and India will see that as a justification not to act. It is up to us to show a lead.”

Caribbean reef fish decline: where have all the big fish gone?

Posted on May 6, 2009 by ovehblog

Humans have been overfishing Caribbean reefs for decades or even centuries. And you don’t have to be a scientists to have noticed. Countless reefs once dominated by vertebrate predators are now nearly devoid of large fish.

Sharks and large grouper and snapper are a rarity on most Caribbean reefs. The reason isn’t a mystery; we simply removed them for sport, profit or sustenance. But the spatio-temporal patterns of predatory fish loss-where and when it happened-and how it was related to factors like proximity to people is largely unknown.

A new study just published in PLoS One by Dr. Chris Stallings sheds some light on the issue by documenting the dissapearence and reduction in size of predatory fish across the Caribbean. The study is based on a publicly accessible, fisheries-independent database of 38,116 reef surveys conducted between 1994 and 2008. Chris examined 20 species of top-level predators, including sharks, groupers, snappers, jacks, trumpetfish and barracuda, from 22 Caribbean nations. He found that nations with more people have reefs with far fewer large fish because as the number of people increases, so does demand for seafood.

Across the region, as human population density increases, presence of large-bodied fishes declines, and fish communities become dominated by a few smaller-bodied species.

[/caption] The study nicely complements another recent study on Caribbean reef fish decline (Paddack et al 2009) covered here in Climate Shifts. One of the many advances of both papers is that they describe the Caribbean-wide loss of reef fish in greater detail than previous local studies. Seeing evidence of this ecological and economic travesty played out across the entire Caribbean is truly sobering. “Although several factors–including loss of coral reef habitats–contributed to the general patterns, careful examination of the data suggests overfishing is the most likely reason we are seeing the disappearance of large predatory fishes across the region,” says Stallings. Species like Nassau grouper, which was once abundant throughout the Caribbean, have completely disappeared from many Caribbean nearshore areas and are endangered throughout their range. “This study also demonstrates the power of volunteer and community research efforts by non-scientists,” – Dr. Chris Stallings Chris used data from the Reef Environmental Education Foundation’s (REEF) online database, which contains fish sightings documented by trained volunteer SCUBA divers, including here over 38,000 surveys spanning a fifteen year period. “Chris was completely undaunted by the lack of fisheries data and essentially adopted the ‘Audubon Christmas Bird Count’ approach in a marine system to find strong evidence for a native fisheries effect,” says Dr. Felicia Coleman, director of the Florida State University Coastal and Marine Laboratory and Stallings’ postdoctoral advisor. Stallings CD, 2009 Fishery-Independent Data Reveal Negative Effect of Human Population Density on Caribbean Predatory Fish Communities. PLoS ONE 4(5): e5333. doi:10.1371/journal.pone.0005333 For additional information, please visit http://www.marinelab.fsu.edu/news/predators

Australia delays emissions trading, but is still comitted to “saving the Great Barrier Reef”

Posted on May 5, 2009 by ovehblog

The Australian Prime Minister Kevin Rudd has ‘changed tack‘ from his post election promises last year in which he said that ‘failure to act on climate change could be disastrous’, and that delaying emission reductions would be “reckless and irresponsible”. Due to the global recession (and presumably other factors), local emissions trading is now halted untill 2011, and of more intrigue, greenhouse gas cuts have been upped 15% to 25% reductions by 2020. See my colleague John Quiggin‘s blog for excellent discussion of conditional & unconditional targets, and 2020 reduction levels. What is worthy of note is this excerpt from the Prime Ministers speech discussing 450ppm as the target for stabilization:

“…the Government has also listened carefully to international and environmental stakeholders committed to realising the best possible outcome at Copenhagen, which is scheduled for the end of this year, in order to achieve the best and most ambitious outcome necessary to stabilise long term greenhouse gas emissions at 450 parts per million, because applied to Australia’s own circumstances long term, that creates the best economic and environmental dividend to Australia, including as I said importantly before, providing a scientific basis for us having a real prospect of saving the Great Barrier Reef.” (Read more)

More than 50% fossil fuel reductions needed by 2050 to meet 2°C climate target

Posted on May 1, 2009 by ovehblog

Less than a quarter of the proven fossil fuel reserves can be burnt and emitted between now and 2050, if global warming is to be limited to two degrees Celsius (2°C), says a new study published in the journal Nature today.

The study has, for the first time, calculated how much greenhouse gas emissions we can pump into the atmosphere between now and 2050, to have a reasonable chance of keeping warming lower than 2°C (above pre-industrial levels) – a goal supported by more than 100 countries (2). We can only emit 1000 billion tonnes of carbon dioxide (CO2) between the years 2000 and 2050. The world has already emitted one third of that in just nine years.

“If we continue burning fossil fuels as we do, we will have exhausted the carbon budget in merely 20 years, and global warming will go well beyond two degrees,” says Malte Meinshausen, lead author of the study and climate researcher at the Potsdam Institute for Climate Impact Research. The three-year research project involved scientists from Germany, the United Kingdom and Switzerland

The study concluded that greenhouse gas emissions must be cut by more than 50 percent by 2050 relative to 1990 levels, if the risk of exceeding 2°C is to be limited to 25 percent.

“Only a fast switch away from fossil fuels will give us a reasonable chance to avoid considerable warming. We shouldn’t forget that a 2°C global mean warming would take us far beyond the natural temperature variations that life on Earth has experienced since we humans have been around,” says Malte Meinshausen. (Link to full story @ Potsdamn Institute for Climate Impact Research)

“Climate change hitting entire Arctic ecosystem, says report”

Posted on April 29, 2009 by ovehblog

The Guardian, 28th April 2008

Extensive climate change is now affecting every form of life in the Arctic, according to a major new assessment by international polar scientists. In the past four years, air temperatures have increased, sea ice has declined sharply, surface waters in the Arctic ocean have warmed and permafrost is in some areas rapidly thawing. In addition, says the report released today at a Norwegian government seminar, plants and trees are growing more vigorously, snow cover is decreasing 1-2% a year and glaciers are shrinking.

Scientists from Norway, Canada, Russia and the US contributed to the Arctic monitoring and assessment programme (Amap) study, which says new factors such as “black carbon” – soot – ozone and methane may now be contributing to global and arctic warming as much as carbon dioxide. “Black carbon and ozone in particular have a strong seasonal pattern that makes their impacts particularly important in the Arctic,” it says.

The report’s main findings are:

Land

Permafrost is warming fast and at its margins thawing. Plants are growing more vigorously and densely. In northern Alaska, temperatures have been rising since the 1970s. In Russia, the tree line has advanced up hills and mountains at 10 metres a year. Nearly all glaciers are decreasing in mass, resulting in rising sea levels as the water drains to the ocean.

Summer sea ice

The most striking change in the Arctic in recent years has been the reduction in summer sea ice in 2007. This was 23% less than the previous record low of 5.6m sq kilometres in 2005, and 39% below the 1979-2000 average. New satellite data suggests the ice is much thinner than it used to be. For the first time in existing records, both the north-west and north-east passages were ice-free in summer 2008. However, the 2008 winter ice extent was near the year long-term average.

Greenland

The Greenland ice sheet has continued to melt in the past four years with summer temperatures consistently above the long-term average since the mid 1990s. In 2007, the area experiencing melt was 60% greater than in 1998. Melting lasted 20 days longer than usual at sea level and 53 days longer at 2-3,000m heights.

Warmer waters

In 2007, some ice-free areas were as much as 5C warmer than the long-term average. Arctic waters appear to have warmed as a result of the influx of warmer waters from the Pacific and Atlantic. The loss of reflective, white sea ice also means that more solar radiation is absorbed by the dark water, heating surface layers further.

Black carbon

Black carbon, or soot, is emitted from inefficient burning such as in diesel engines or from the burning of crops. It is warming the Arctic by creating a haze which absorbs sunlight, and it is also deposited on snow, darkening the surface and causing more sunlight to be absorbed.

Climate change – is the ‘missing science’ really missing?

Posted on April 27, 2009 by ovehblog

The now infamous skeptic Professor Ian Plimer launched his seventh book last week, titled “Heaven and Earth, Global Warming: The Missing Science“. Apparently Plimer, a Professor of Mining and Geology from the University of Adelaide is aiming to ‘refute every scientific argument that humans are responsible for global warming’. Remember that this is the same Professor who believes that “… the Great Barrier Reef will benefit from rising seas, that there is no correlation between carbon dioxide levels and temperature, that only 0.1 % of carbon dioxide emissions are due to human activities, and that 96% of the greenhouse effect is due to water vapour.”

Professor Plimer said his book would “knock out every single argument we hear about climate change”, to prove that global warming is a cycle of the Earth.

“It’s got nothing to do with the atmosphere, it’s about what happens in the galaxy.

“You’ve got to look at the whole solar system and, most importantly, we look back in time.

“There’s a lot of talk out there that there isn’t any science that supports my view, but I have 2111 scientific references in this book.”

Following the booklaunch, the Australian newspaper published an entertaining read titled ‘Climate sceptics ready to storm heaven with earth’s geological history‘, detailing the plight of Dr Barry Brook, who as the head of Adelaide University’s Research Institute for Climate Change and Sustainability is at the opposite end of the spectrum when it comes to academic debate (apparently Dr Brook is ill-fated enough to share a hallway just metres away from the good Professor Plimer)

Defending climatologists and thousands of other scientists, Barry Brook, who heads Adelaide University’s Research Institute for Climate Change and Sustainability, poured cold water on Professor Plimer’s book and said his colleague had only used “selective evidence” when quoting more than 200 scientists and from peer-reviewed papers.

Professor Plimer’s “stated view of climate science is that a vast number of extremely well respected scientists and a whole range of specialist disciplines have fallen prey to delusional self-interest and become nothing more than unthinking ideologues”, he said.

“Plausible to conspiracy theorists, perhaps, but hardly a sane world view, and insulting to all those genuinely committed to real science.”

Is the ‘missing science’ really missing? Over at Brave New Climate, Professor Brook systematically dismantles Plimer’s arguments:

Ian Plimer’s book is a case study in how not to be objective. Decide on your position from the outset, and then seek out all the facts that apparently support your case, and discard or ignore all of those that contravene it. He quotes a couple of thousand peer-reviewed scientific papers when mounting specific arguments. What Ian doesn’t say is that the vast majority of these authors have considered the totality of evidence on the topic of human-induced global warming and conclude that it is real and a problem. Some researchers have show that the Earth has been hotter before, and that more CO2 has been present in the atmosphere in past ages. Yes, quite — this is an entirely uncontroversial viewpoint. What is relevant now is the rate of climate change, the specific causes, and its impact on modern civilisation that is dependent, for agricultural and societal security, a relatively stable climate. Ian pushes mainstream science far out of context, again and again.

Perhaps most telling is the following ABC radio interview with Kurt Lambeck, Professor of Geophysics at Australian National University, and the President of the Australian Academy of Science. Lambeck was extensively cited by Plimer in one of the chapters of “Heaven and Earth, Global Warming”, and he doesn’t appear to be very happy at how Plimer has interpreted his work:

[audio:http://67.220.225.10/~clim2165/cs/audio/plimer.mp3]

Seems like Plimer has adopted the Bob Carter obfuscation approach to climate skepticism. I’m surprised that his words carry so much weight, and echo Lambeck’s concern that “Heaven and Earth, Global Warming” has ‘… the potential to derail any political commitment to action on climate change in Australia’.

A world without fish – what would it take?

Posted on April 27, 2009 by ovehblog

“A Sea Change – Imagine a World Without Fish” is a recently released documentary film about ocean acidification, the little-known ugly sister of global warming. The film website www.aseachange.net explains it “… aims not only to educate viewers about the science of our rapidly-changing oceans, but also to engage them on accessible terms.”
The full film was shown to the European Geosciences Union 2009 conference on 27 April 2009, a podcast of which is available here. After a 2 minute introduction, the film lasts for 19 minutes followed by an illuminating question and answer session.

Caribbean fish decline in the wake of coral collapse?

Posted on April 25, 2009 by ovehblog

A new study in Current Biology (some really interesting coral related stuff being published there lately) by Michelle Paddack and colleagues (Paddack et al 2009) documents a region-wide decline in reef associated fish in the Caribbean. The authors conducted a meta-analysis on a substantial amount of fisheries-independent, time-series data on Caribbean fish densities. Fish densities seem to have been pretty stable from the mid-50s until the mid-90s, to then exhibit significant negative rates of change during the past 10 years. What is striking is the generality of the decline that has occured the past decade, across the whole region (see figure below)

Recorded declines in fish densities across five Caribbean sub-regions 1996-2007

Differences in fished and non-fished species were non-significant. This leads the authors to speculate that fishing is not the main driver of these changes (although certainly it plays a part). Rather, as has been documented in the western Indian Ocean, these changes in fish communities could be a response to the substantial losses of coral cover which have occurred in the Caribbean the past decades. A wicked problem, primarily for managers and communities dependent on fisheries, is that changes in fish communities seem to manifest themselves as a form of “degradation debt” – that is, there is a substantial time-lag between changes in the underlying benthic community and the response of fish communities.