Tag Archives: Science & Politics

Is there a case for the “bacterial bleaching hypothesis’? Oculina patagonica / Vibrio shiloi revisited

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The idea that mass coal bleaching is caused by bacteria bleaching as opposed to temperature stress has been quite a contentious issue over the past decade. Despite the fact that massive amounts of evidence that have accumulated that support the idea that thermal stress has driven the mass episodes of coral bleaching (pigment loss associated with the dissociation of the symbiosis between coral and their dinoflagellates) over the past 30 years, some oxygen has been given to the alternative idea that mass coral bleaching is triggered by the presence of bacteria from the genus Vibrio.The idea that bacteria were involved in triggering coral bleaching originated from work done on the temperate coral Oculina patagonica from the Mediterranean sea (an invading species from the Atlantic coast of South America) seemed to suggest that the annual coral bleaching was due to a bacterial infection from a putative pathogen, Vibrio shiloi.

This discussion focuses on recent work done by my laboratory and which was published in the Nature journal ISME (download here) and which suggests that bacteria are not responsible for triggering mass coral bleaching (in O. patagonica or anything else). We are interested in your thoughts and hope that you will comment in the hope of resolving debate over this issue for once and for all.

The Bacterial Bleaching Hypothesis is based on a series of eloquent microbiological investigations conducted by Eugene Rosenberg and his group revealed the intra-cellular penetration, multiplication and subsequent cellular lysis of zooxanthellae by V.shiloi resulted in the annual bleaching of O.patagonica in temperatures above 28ºC. Since then, the bacterial bleaching hypothesis has been extrapolated as an explanation for global mass coral bleaching, and more recently, the coral ‘probiotic hypothesis’ (link). To some (including Eugene Rosenberg), the workplace emphasis onto bacteria rather than climate change as the cause for mass coral bleaching – the implications for the future of coral reefs would be highly significant if Rosenberg were correct.

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Isobel Bennett, Australian coral reef pioneer dies

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It is with great sadness that I post that Isobel Bennett, a pioneer and founder of coral reef science in Australia and author of the book “The Great Barrier Reef” has passed away this week (see below for an obituary from The Age newspaper). Isobel was a truely unique person and one of Australia’s most distinguished marine sciences, and her death comes as a true loss to the scientific community. Click here for a link to an extensive interview conducted by the Australian Academy of Science detailing the life of one of “the last great naturalists”.

Seashore and reef expert dies at 98

The Age, January 14th 2008

A PIONEERING marine scientist who had a coral reef named after her has died at 98.

Isobel Bennett, who left school at 16 and went on to become a seashore expert, passed away at a nursing home in Mona Vale, in northern Sydney, yesterday.

Len Zell, a lecturer in marine and tropical biology at James Cook University, said Ms Bennett was schooled in the “university of life”, and had an insatiable curiosity. “She achieved high standing as an Australian marine scientist, not by education, but by sheer hard work, determination, attention to detail, and a never-ending curiosity that tired me out lifting boulders on many reef flats,” he said.

“The last time I was on Heron Island with her she was in her 80s, and we spent hours out on the reef flat turning boulders and photographing and discussing the critters there.”

Ms Bennett, who was awarded an honorary doctorate by NSW University, was born in Brisbane in 1909 and, as the eldest of four children, left school at 16 to enter the workforce.

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Humans Have Caused Profound Changes In Caribbean Coral Reefs

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ScienceDaily, January 9th

Coral reefs in the Caribbean have suffered significant changes due to the proximal effects of a growing human population, reports a new study.

“It is well acknowledged that coral reefs are declining worldwide but the driving forces remain hotly debated,” said author Camilo Mora at Dalhousie University, Halifax, Canada. “In the Caribbean alone, these losses are endangering a large number of species, from corals to sharks, and jeopardizing over 4 billion dollars in services worth from fisheries, tourism and coastal protection,” he added.”The continuing degradation of coral reefs may be soon beyond repair, if threats are not identified and rapidly controlled,” Mora said. “This new study moves from the traditional localized study of threats to a region-wide scale, while simultaneously analyzing contrasting socioeconomic and environmental variables,” he added.

The study monitored coral reefs, including corals, fishes and macroalgae, in 322 sites across 13 countries throughout the Caribbean. The study was complemented with a comprehensive set of socioeconomic databases on human population density, coastal development, agricultural land use and environmental and ecological databases, which included temperature, hurricanes, productivity, coral diseases and richness of corals. The data were analyzed with robust statistical approaches to reveal the causes of coral reef degradation in that region.

The study showed clearly that the number of people living in close proximity to coral reefs is the main driver of the mortality of corals, loss of fish biomass and increases in macroalgae abundance. A comparative analysis of different human impacts revealed that coastal development, which increases the amount of sewage and fishing pressure (by facilitating the storage and export of fishing products) was mainly responsible for the mortality of corals and loss of fish biomass.

Additionally, the area of cultivated land (a likely surrogate for agrochemical discharges to coral reefs) was the main driver of increases in macroalgae. Coral mortality was further accelerated by warmer temperatures.

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“Stop the warming disinformation”

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One of the most astute “letters to the editor” i’ve seen in a while:

Re “Gore’s cult of global alarmism,” commentary, Dec. 26: I was astounded to see The Bee print such a profoundly ignorant column about the climate change issue. Columnist Cal Thomas claims that the scientific debate on the issue hasn’t even begun, because those who believe global warming is a serious issue won’t debate with their critics.

If there was ever a scientific consensus on an issue, it’s this one. This year’s Intergovernmental Panel on Climate Change report is its fourth major scientific conclusion on the issue in recent decades, and it is the most alarming yet. People like Thomas can always find a scientist or two trying to poke holes in the views of the overwhelming majority, but the truth of the climate situation is abundantly clear to anyone willing to examine the evidence.

Thomas cites a report by the Republican staff of a Senate committee. With the current Republican administration’s track record of blocking action on climate change, that is a laughable source.

Thomas even presents as fact ExxonMobil’s claims that it cares about climate change, and that it doesn’t fund global warming skeptics. Just how gullible does Thomas think we are? The time for debate is over. It’s time to get serious about addressing climate change.

Barrier Reef’s future clouded (The Australian Newspaper)

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The Australian, 14th December 2007
It is probably too late to save the Great Barrier Reef and other coral reefs from global warming.
Even if governments implement far-reaching measures to cut greenhouse gas emissions, they will not prevent the annihilation of coral reefs around the world.

These are the conclusions of analysis by leading marine scientists to be published today in the prestigious journal Science.

“There is a terrible future in front of us for the reefs,” said Canada-based United Nations University professor Peter Sale, one of 17 authors from seven nations of the Science paper.

On Wednesday, Kevin Rudd told the UN’s Bali climate change conference that global warming was threatening Australian natural wonders such as the Great Barrier Reef, Kakadu National Park and rainforests, killing rivers and exposing people to more frequent and ferocious bushfires.

The scientists present three scenarios for the future of coral reefs – the world’s largest lifeforms – under different climatic conditions.

If current conditions continue, with the stabilisation of temperatures and emissions at today’s level of 380 parts per million, reefs will survive but undergo fundamental changes.

However, scientists agree that stabilisation of current conditions is not possible. The paper warns that if emissions rise to between 450 and 500ppm, with an associated temperature rise of 2C by 2050 – the most optimistic outcome predicted by the landmark study by British economist Nicholas Stern – reefs will suffer “vastly reduced habitat complexity and loss of biodiversity”.

But if they rise above 500ppm, the minimum emission level forecast by the UN’s Intergovernmental Panel on Climage Change by 2050, reefs will become “rapidly eroding rubble banks”.

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Global action call to save reefs

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Eminent coral scientists have given world leaders in Bali more reason to act urgently against climate change, by producing a new report that warns coral reefs will disappear within decades if atmospheric CO2 levels continue to rise.

Their paper, published today in the prestigious Science magazine, is the most compelling scientific case yet that unchecked global warming will be a disaster for coral reefs and the 100 million people and one million species depending on them.

CO2 concentration in the earth’s atmosphere is currently 380 parts per million (ppm) but the authors say if future emissions exceed 450ppm we risk losing reefs.

“This is a very ambitious target and should represent yet another reality check for world leaders meeting in Bali,” lead author UQ Professor Ove Hoegh-Guldberg said.

Reducing CO2 emissions must also be accompanied by reducing reef risks such as overfishing, pollution and unsustainable coastal developments, a cross-section of the report’s authors (all of whom are members of the Coral Reef Targeted Research and Capacity Building for Management Program, CRTR) said at UQ.
Tools needed to reduce stress on coral reefs already exist, and include: increased protection of river catchment and coastal areas; co-management arrangements between governments and local communities; improved catchment, water quality and environmental flow measures; fishing regulation enforcement; restoration of reefs and coastal vegetation; and sustainable tourism.
The study has found serious consequences follow on from even small increases in CO2.

“The warmer and more acidic oceans caused by the rise of CO2 from the burning of fossil fuels threaten to destroy coral dominated reef ecosystems, exposing people to flooding, coastal erosion and the loss of food and income from reef-based fisheries and tourism,” Professor Hoegh-Guldberg said.
“This is happening just when many nations are hoping that growing industries like tourism and fisheries will allow them to develop beyond their often impoverished state.
“Increased CO2 not only warms the climate but also dissolves in sea water making it more acidic.
“This, in turn, decreases the ability of corals to produce calcium carbonate, which is what the all-important framework of coral reefs is made of.”

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Coral reefs as CO2 sinks?

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An interesting article that has appeared in the news recently suggests that countries in the Asia Pacific region have proposed to utilise their coral reefs as carbon sinks under the new climate change protocol being developed in Bali.

Indonesian Fisheries and Marine Affairs Minister, Freddy Numberi, who opened the six countries’ senior official meeting to discuss the action plan to conserve the coral area, said that the area, which is dubbed as the Amazon of the Seas because it contains 53 percent of the world’s coral reef and over 3,000 fish species, was the earth’s epicenter of marine life and diversity.

“We have made efforts to conserve it during the past five years, so we want the world to appreciate it. One of the ways is to include it into the Kyoto Protocol framework so that it can be turned into a carbon sink, and later trade it for carbon credit,” Freddy told reporters. (Read more)

On the topic of coral reef sequestration of carbon, Dr Thomas Goreau from the Global Coral Reef Allience (a delegate at the United Nations conference in Bali) has the following to say:

Not only is the entire claim that coral reefs are a CO2 sink completely incorrect, they are in fact a source of CO2 to the atmosphere even while they remove carbon from the ocean. This has been understood by carbonate chemists for a very long time but we keep having to deal with this popular error over
and over again.

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Australia ratifies Kyoto

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As Ecolog reports that green house gas emissions reach near-record level highs, Australian Prime Minister Kevin Rudd has broken the stalemate and ratified kyoto just weeks after coming into power on his first day in office. Senator Penny Wong, the newly instated Minister for Climate Change, was quoted to say that the decision sets Australia up for a leadership role at the United Nations Climate Change conference in Bali later this month.

“Ratifying the Kyoto Protocol puts Australia back on the map,” she said.

“The world now knows that this nation is prepared to do its bit and be part of the global solution to climate change. This gives us an impetus to go into the Bali conference to set that leadership role. The purpose of the Bali conference is to set out the road map for what happens post the Kyoto period. We want to ensure that what we agree in Bali gives Australia and the world the best chance to moving towards a solution on climate change.”

Rudd’s decision has run into some interesting commentary in the news. Despite previous concern of greenhouse gas emissions from India and China, The India Times ran with the headline “India to gain as Australia signs Kyoto“, quoting “India smiled from the sidelines knowing that, in the least, it would augur well for Indian industry and, at best, would push its case in global negotiations. Meanwhile, Germany’s Environment Minister has called for an international market in carbon dioxide emissions to combat climate change, with a stronger focus on emission reduction from G8 countries and emerging nations. A joint statement released at the 10th China – European Union Leaders meeting has further stressed the importance of climate change and the willingness to cooperate in stabilising and reducing greenhouse gas emissions.

As one astute commentator summarised, “No continent is an island“, but all this leaves the ABC news wondering “Can climate progress succeed without the US?”

More commentary from me on this during the lead up to Bali.