Resilient ‘super reefs’ a priority for conservation efforts

Posted on April 24, 2009 by ovehblog

picture-354
ScienceDaily, 23rd April 2009

The Wildlife Conservation Society announced today a study showing that some coral reefs off East Africa are unusually resilient to climate change due to improved fisheries management and a combination of geophysical factors. WCS announced the results of the study at the International Coral Reef Initiative (ICRI), which is meeting this week in Phuket, Thailand.

The study, published in the online journal Aquatic Conservation: Marine and Freshwater Ecosystems, provides additional evidence that globally important “super reefs” exist in the triangle from Northern Madagascar across to northern Mozambique to southern Kenya and, thus, should be a high priority for future conservation action.

Authors of the study include Tim McClanahan and Nyawira Muthiga of the Wildlife Conservation Society, Joseph Maina of the Coral Reef Conservation Project, Albogast Kamukuru of the University of Dar es Salaam’s Department of Fisheries Science and Aquaculture, and Saleh A.S. Yahna of the University of Dar es Salaam’s Institute of Marine Sciences and Stockholm University’s Department of Zoology.

The study found that Tanzania’s corals recovered rapidly from the 1998 bleaching event that had wiped out up to 45 percent of the region’s corals. Along with monitoring Tanzania’s reefs, WCS helps coral conservation in this region through training of park staff in protected areas.

The authors attribute the recovery of Tanzania’s coral reefs due in part to direct management measures, including closures to commercial fishing. Areas with fishery closures contained an abundance of fish that feed on algae that can otherwise smother corals, while the few sites without any specific management measures remain degraded; one site had experienced a population explosion of sea urchins—pests that feeds on corals.

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Doom and Boom on a Resilient Reef: Climate Change, Algal Overgrowth and Coral Recovery

Posted on April 22, 2009 by ovehblog

Our lab has just published a new paper in PLoS ONE, detailing the interactions of coral and algae on the Great Barrier Reef, and uncovered just how resilient some reefs can be following coral bleaching events. The southern end of the Great Barrier Reef was exposed to extended periods of high sea surface temperatures in the end of 2006, resulting in extensive coral bleaching across the Keppel Islands throughout January 2006. Following the bleaching event, a single species of fleshy macro-algae (Lobophora) overgrew the coral skeletons, causing high rates of mortality throughout the second half of 2006. But, by February 2007, corals were rapidly recovering due to an unusual seasonal dieback of the macro-algae, and astonishing regenerative capabilities of the dominant branching Acroporid corals – almost twice the rate of offshore corals on the northern Great Barrier Reef.

What is unusual about the Keppel Islands story is threefold: first, that corals recovered within months to years (reversal of macro-algae dominated reefs often takes decades), second, recovery of the corals occurred in the absence of herbivory (traditionally assumed to be the ‘driving factor’ in macro-algal phase shifts), and third, that corals recovered through asexual (regenerative) capacities rather than reseeding of reefs by larval recruitment. Understanding the processes that drive recovery following disturbances is critical for management of coral reefs, and the Keppel Islands example shows that managing local stressors (overfishing and water quality) helps reefs bounce back from global stressors such as coral bleaching events. PLoS One is an open-access journal, so the article is free to read – click on the link below, and feel free to rate and comments on the paper. Congratulations Guillermo et al!

Guillermo Diaz-Pulido, Laurence J. McCook, Sophie Dove, Ray Berkelmans, George Roff, David I. Kline, Scarla Weeks, Richard D. Evans, David H. Williamson, Ove Hoegh-Guldberg (2009 Doom and Boom on a Resilient Reef: Climate Change, Algal Overgrowth and Coral Recovery. PLoS ONE 4(4): e5239. doi:10.1371/journal.pone.0005239

The worlds most overpopulated coral reef?

Posted on April 21, 2009 by ovehblog

I remember seeing a fascinating presentation by Mahmood Riyaz on the reef slope failure of this coral reef at the ICRS conference in Florida last year – how the atoll rim was cracking due to the sheer amount of construction and concrete. Welcome to Male, the capital of the Maldives, where >100,000 people are crammed ontop of a coral reef atoll only 1.7km in length. The Maldives have been hit hard in recent years, collectively lost over 2/3 of it’s coral following the 1998 bleaching event. In addition, being such a low lying country is likely to be problematic given the projected sea level rises, so the Maldivian government is proposes a carbon neutral approach by 2020, and is even considering diverting some of the billion dollar tourism profits to purchase a new homeland. The photo above doesn’t do justice to the population density on such a tiny atoll – check the satellite images on google earth.

Policy changes and paradigm shifts following Copenhagen

Posted on April 19, 2009 by ovehblog

The United Nations climate conference in Copenhagen (which I attended ) was an excellent initiative, with some fairly interesting insights into the gulf between science and policy making. Following the conference, we were contacted by The Guardian newspaper to participate in a poll on global warming. The results are striking – almost 90% of climate scientists ‘do not believe political efforts to restrict global warming to 2C will succeed’, and that ‘an average rise of 4-5C by the end of this century is more likely’.

The poll of those who follow global warming most closely exposes a widening gulf between political rhetoric and scientific opinions on climate change. While policymakers and campaigners focus on the 2C target, 86% of the experts told the survey they did not think it would be achieved. A continued focus on an unrealistic 2C rise, which the EU defines as dangerous, could even undermine essential efforts to adapt to inevitable higher temperature rises in the coming decades, they warned.

The survey follows a scientific conference last month in Copenhagen, where a series of studies were presented that suggested global warming could strike harder and faster than realised.

The Guardian contacted all 1,756 people who registered to attend the conference and asked for their opinions on the likely course of global warming. Of 261 experts who responded, 200 were researchers in climate science and related fields. The rest were drawn from industry or worked in areas such as economics and social and political science.

The 261 respondents represented 26 countries and included dozens of senior figures, including laboratory directors, heads of university departments and authors of the 2007 report from the Intergovernmental Panel on Climate Change (IPCC). (Read more)

This sobering news isn’t helped by reports that Steven Chu, the US Secretary for Energy (who I blogged on back in February) has done a complete backflip on statement that coal as ‘his worst nightmare‘, and is now endorsing ‘clean coal‘ technologies. ‘Clean coal’ is a complete myth, and thankfully the US Environmental Protection Agency have passed a motion to deem 6 greenhouse gases (carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride) as ‘dangerous to the public‘, opening up legislation to regulate powerplants and the automotive industry. It will be interesting to see exactly where the Obama administration will take the United States under the new environment and climate change policies, which aim to invest $150 billion in clean energy and renewable sources.

New coral reef blog on the scene

Posted on April 19, 2009 by ovehblog

One of my PhD Students, Siham Afatta, has started a new science blog called ‘Laut & Kita’ (Sea & Us). Siham (a seasoned blogger) is targeting this as one of very few scientific blogs written in Bahasa (the official language of Indonesia), which focuses primarily on marine conservation in Indonesia. I think this is a great effort and great example of the power of blogging – check out the link below.

New evidence from coral reefs suggest sea level rise occurs over ecological time scales

Posted on April 18, 2009 by ovehblog

Paul Blanchon and his team have uncovered evidence of extremely rapid sealevel rise 121,000 years ago in one of the warm interglacial periods. Basically by dating coral skeletons at a place called Xcaret (the beautiful place where a fossil Reef lies exposed), Paul was able to document an abrupt reef crest “back stepping” (essentially the reef crest suddenly appearing landward in a very short time). The abrupt loss of the lower reef crest growth but continued growth between the lower and upper reef crests has allowed these paleobiologist to draw the conclusion that this occurred due to a 2-3 m sea level rise. What is the big news, is that it happened over decades. Measurements of the upward growth of some corals at the “ocean surface” occurred at about 36 mm per year!

Paul is scientist who is characterised by rigour and excellence. He is based at Institute of Marine Sciences and Limnology (ICML) of the National Autonomous University of Mexico (UNAM) in Puerto Morelos on the Yucatan Peninsula. As a paleobiologist, he is interested in how the world has changed over thousands of years. For a long time now, Paul has been gathering evidence the great ice sheets the world can break up suddenly over very short period of times. This latest paper is further evidence of the veracity of this idea – follow this link to see the article in Nature.

Editor’s Summary
16 April 2009

An interglacial jump in sea level

The potential for future rapid sea-level rise is perhaps the greatest threat from global warming. But the question of whether recent ice loss from Greenland and Antarctica is the first indication of such a rise is difficult to answer given the limited duration of the instrumental record. New evidence from an exceptionally exposed fossil reef in the Xcaret theme park in Mexico provides a detailed picture of the development of reef terraces, erosion surfaces and sea-level excursions in the region during the last interglacial. A combination of precise uranium-series dating and stratigraphic analysis, together with comparison with coral ages elsewhere, suggests that a sea-level jump of 2 to 3 metres occurred about 121,000 years ago, consistent with an episode of ice-sheet instability towards the end of the last interglacial. On that evidence, sustained rapid ice loss and sea-level rise in the near future are possible.

Spring Cleaning

Posted on April 18, 2009 by ovehblog

Climate shifts web guru and contributor Jez Roff has an eye for peculiar marine critters and phenomena including large worms, pink dolphins , giant crabs, and fashionable turtles.

He is the lead author of a new Reef Site article published in the journal Coral Reefs about corals that extrude mesenterial filament to tidy up new surfaces before then grow onto them.

Peripheral polyp mesenterial filaments at the lesion margins were observed to actively “sweep” and remove detritus within the perimeter surrounding the recovering lesions (Fig. 1b). Our observations of pre-emptive cleaning appeared to be linked with extracoelenteric digestion of detritus by the mesenterial filaments (Fig. 1c), exposing the glass slide to a width of several polyps. The continuous removal of detrital and algal material facilitated tissue expansion by the prevention of competitor settlement and by the preparation of substrates for calcified coral growth (Fig. 1d).

sweepers

Fig. 1 a Accumulation of detrital matter on glass slides following lesion induction of Acropora pulchra branches. b Pre-emptive cleaning of substrates (perimeter marked by black arrows) surrounding growing margins ofAcropora pulchra by mesenterial filaments (white arrows). c Close-up of protruding mesenterial filaments actively feeding and removing detritus. d Tissue growth and calcification onto cleaned surface 90 days following lesion formation (scale = 3 mm)

The secret history of nuclear testing and coral reefs

Posted on April 13, 2009 by ovehblog

I stumbled cross these stunning satellite images of Bikini and Enewatak Atoll on the Artificial Owl blog. Top left is a 2000m crater left by Castle Bravo in 1954, the second biggest thermonuclear hydrogen bomb (weighing in at 15 megatons, 1200 times more powerful than Hiroshima). Top right is the 120m blast crater in the reef flat created by the Cactus test in 1958. The ‘dome’ construction on the island in the same image is a concrete cover built in 1977 to cover over 85,000 cubic metres of radioactive soil and debris from across the Marshall Islands. I’m staggered by the scale of these tests – whilst I remember the end of the French underground nuclear weapons testing at Muroroa and Fangataufa Atolls in the late 1990’s (after 147 tests had been conducted), I had no idea of the sheer size of the early impact craters left from earlier explosions. The good news is that recent surveys of the coral reefs surrounding Bikini Atoll shows signs of recovery from the disaster, and the bomb crater itself now supports vibrant and diverse coral communities. However, when compared to surveys conducted ‘pre-bomb’ in the early 1950’s, at least 28 species of coral have now become locally extinct, most likely as a result of the initial impact, radiation, increased sedimentation or altered atoll hydrology. A few highlight pictures are featured below, but go check out the original postings here and here for more information and photographs.

Geoengineering, climate change and ‘albedo flips’

Posted on April 10, 2009 by ovehblog

As it has become increasingly clear that we are well into a period of dangerous or even catastrophic climate change, discussions about geoengineering have become more intense and public. Now the US government is openly admitting that it too is discussing the pros and cons of geo-engineering. This article includes some fascinating insights into these discussions. Newly appointed White House science advisor, John Holdren, told the Associated Press, for example, that “as the global climate picture gets gloomier, geoengineering is sneaking into White House conversations”.

“It’s got to be looked at,” Holdren said. “We don’t have the luxury of taking any approach off the table.”

Percentage of diffusely reflected sun light in relation to various surface conditions of the Earth (source: Wikipedia)

Sounds to me like geoengineering is very much on the agenda! There are various aspects which contribute to the diffuse reflectivity of the planet – such as clouds, ice and snow and even vegetation. The graph on the left shows the various contributions of different aspects of the planet to its albedo. These various characteristics have a powerful role in determining the earth temperature. The recent loss of summer Arctic ice is a case in point. Calculations show that the resulting “albedo flip” from reflective ice to darker ice-free ocean will dramatically increase the energy being absorbed by the earth and drive its temperature upward by over a degree Celsius.

Various ideas have been floated about on how to increase the reflectivity of the earth – including pumping reflective particles into the outer atmosphere of the earth in order to bounce more energy back into space. These calculations suggest that relatively small amounts of material could lower the earth’s temperature by as much as 1-2°C. The contribution to lowering temperature such as this would certainly take some of the pressure off and buy us important time as we urgently struggle to get greenhouse emissions under control.

But there is reason for great caution. Apart from the fact that there are many uncertainties and unknowns (i.e. are we certain that we know how much of these yet-to-be-invented particles to add to the atmosphere?), there is the concern that offering this option will take the pressure off governments to act decisively on the problem of fossil fuels and their emissions. It also has a range of legal and ethical issues. For example, should any particular government be able to unilaterally decide whether or not to manipulate the earth’s albedo and temperature without the agreement from all? And if manipulating temperature downward were to result in deaths from cooling temperatures or disturbances in the weather, what then?

And it is important to remember that changing the albedo of the earth will not solve all the problems associated with upwardly spiralling atmospheric carbon dioxide. For example, decreasing the temperature of the planet will do nothing to solve the problem of ocean acidification.

“What will global warming look like? Scientists point to Australia”

Posted on April 9, 2009 by ovehblog

http://video.latimes.com/global/video/flash/widgets/WNVideoCanvas.swf

Los Angeles Times Online (April 9th 2008): They call Australia the Lucky Country, with good reason. Generations of hardy castoffs tamed the world’s driest inhabited continent, created a robust economy and cultivated an image of irresistibly resilient people who can’t be held down. Australia exports itself as a place of captivating landscapes, brilliant sunshine, glittering beaches and an enviable lifestyle.

Look again. Climate scientists say Australia — beset by prolonged drought and deadly bush fires in the south, monsoon flooding and mosquito-borne fevers in the north, widespread wildlife decline, economic collapse in agriculture and killer heat waves — epitomizes the “accelerated climate crisis” that global warming models have forecast.

With few skeptics among them, Australians appear to be coming to an awakening: Adapt to a rapidly shifting climate, and soon. Scientists here warn that the experience of this island continent is an early cautionary tale for the rest of the world.” (Link to full article)

Climate Shifts

Life in a rapidly changing climate