April 2012 – Elevated CO2 alters CCA-larval interactions
Chris’ first PhD paper will be published in the April edition of Ecology Letters. The work describes the findings of a series of 3 month long aquarium experiments where we identified how elevated CO2 alters crustose coralline algal (CCA) community structure and reduces rates of coral settlement. Most surprisingly, we found that the only preferred settlement substrate in ambient conditions (Titanoderma, a species of CCA) was avoided by coral larvae as CO2 increased. The results suggest that ocean acidification may interfere with coral population recovery by reducing coral settlement rates, disrupting settlement behaviour, and reducing the availability of the most desirable substrate for successful coral recruitment.
Doropoulos C, Ward S, Diaz-Pulido G, Hoegh-Guldberg O, Mumby PJ (2012) Ocean acidification reduces coral recruitment by disrupting intimate larval-algal settlement interactions. Ecology Letters. 15, 338-346.
http://onlinelibrary.wiley.com/doi/10.1111/j.1461-0248.2012.01743.x/abstract
Acropora millepora settled on Titanoderma.
March 2012 – Field work in Palau, Micronesia
Sonia, Jez, Alyssa and Pete were joined by Bob Steneck to work on the effects of wave exposure on coral reef processes in March 2012. They were also joined by their partners at the Palau International Coral Reef Center, Dr Yimnang Golbuu and Lukes Isechal. It was challenging work because a gradient of wave exposure means setting down experiments in some of the most exposed reef environments but once you got used to being in a washing machine all went smoothly. The only incident of interest was a close encounter between Pete and a 10ft bull shark who took exception to have someone survey fish in his territory.
While we were there, we joined Bob Richmond and Rod Salm in discussing reef conservation issues with the Palauan Congress (organised by the Speaker of the House, Noah Idechong).
February 13th 2012 – MSEL summer research on Heron Island
Alyssa, Chris and Jez have been up at Heron Island for the past couple of weeks. They lucked out with amazing weather, so have decided to take full advantage of it. Working on Alyssa’s surgeonfish grazing and Chris’s coral recruitment projects, the three MSEL bandits and their two volunteers (Julia and YY) have been diving up a storm. Currently, Alyssa is quantifying herbivorous fish distribution and abundance, surgeonfish grazing rates, and turf algal productivity around the reef. Chris is doing the final field trip for his PhD, where he has been quantifying coral settlement, early growth rates, and survivorship, on the reef slope and flat at Heron for the past 3 years, which Jez will continue and expand upon as part of his Post-doc. – Chris Doropoulos
Julia measuring rugosity
Alyssa using stereoscopic video cameras
Quadrat surveys of benthic cover
Chris and Alyssa surveying for parrotfish, rabbitfish and surgeonfish
Team MSEL! Julia, Chris, Jez, Alyssa (YY behind the camera!)
And a big thanks to MSEL volunteers Julia (left) and YY (right) for their assistance with this research.
July 18th 2011 – Biases in fish surveys highlighted by distances of fish detection
Photos: M. Gonzalez RiveroA recent study led by Yves-Marie Bo
zec (MSEL postdoc) together with researchers from the French Institute of Research for Development (IRD), and Agrocampus Ouest in France, investigated the ability of SCUBA divers to detect fish during underwater visual censuses (UVC). Using the distance sampling method, they show that most fish actually flee before being detected, thus introducing major bias in fish surveys.
Distance sampling is a widely-used technique for estimating the abundance of wildlife populations. It involves the assessment of distances at which a species is detected perpendicular to a reference line. The distribution of distances reflects the probability of detecting a species at any distance: a perfect detectability implies that the number of detections is constant as distance increases. In New Caledonia, researchers from IRD have performed distance sampling-based UVC since the mid 1980′s, thu
s producing a large database of detection distances for more than 500 fish species. Their analysis reveals that fish detection for a given size and behaviour is more likely to occur at a particular distance from the transect line.
For most fish, the number of detection increases with distance, indicating evasive movement of fish prior to detection. The distance of maximum detection correlates with body size, so that the larger the fish, the greater the fleeing distance. Furthermore, species classified as “shy”, independently from their size, flee at farther distances. Inversely, cryptic and camouflaged fish are hardly detected beyond 1 meter.
On coral reefs, fish are usually surveyed using strip transects, whereby every fish detected within the strip is counted. This technique assumes that the probability of detecting fish at any distance is, at best certain, at least uniform within the boundaries of the strip. Distance data show how this assumption is violated when using a particular strip width, and how much density estimates can be consecutively affected. Of particular concern is that the magnitude of biases (such as evasive movements) may be inconsistent over time and among reefs. In addition, ecological studies aiming at comparing surveys with different strip widths are likely to produce misleading results. The present study calls for more research on UVC techniques in order to reduce inconsistent biases in fish density estimates.
Friday July 8th 2011 – Groupers keep lionfish population under control
(via Amigoe Nieuws, Caribbean) Peter Mumby, the project-coordinator of the international research team ‘Future of Reefs in a Changing Environment’ (Force) has conducted research together with a team of researchers from the University of Queensland, Australia and the American Museum of Natural History from New York into the presence and the effect of the grouper on the undesirable fish species, the lionfish.
The local Carmabi researchers are also involved with the Force-initiative. The European Community (EU) is financing the Force-team for a five-year project with an amount of six million euros. Mumby, who lives in Australia and is associated with the University of Brisbane and the University of Queensland, concludes: “The grouper could limit the invasion of the lionfish in the Caribbean area. The lionfish, which are not seen in the Caribbean area by nature and of which one assumes they were released from aquaria in the United States, gradually found their way to the Bahamas in 2004.”
The conclusion is that the lionfish has ‘increased dramatically’ in numbers the past years and that we now have a complete ‘invasion within the Caribbean area’. Mumby speaks of the entire fear (within the scientific community) about the possible detrimental effect of the lionfish on the native fish population. The universities of Queensland and the American Museum of Natural History have studied the invasion in a remote plain of the coral reef on the Bahamas. Within the marked study fields, the number of lionfish was a tenfold lower than at reeves where the large grouper feeds.
“With a long term protection for over-fishing, we were able to observe the highest number of groupers in the Caribbean area and we think they will eat sufficient lionfish to suppress the invasion on these reeves,” according to the researcher. Within the attempts to conserve, the findings of this study are considered positive. Nevertheless, Mumby warns: “The years of over-fishing means that the number of groupers, such as the Nassau grouper (Nassau bass – Epinephelus striatus), is low in the Caribbean region. If we want the grouper to help us combat the lionfish, we should develop a taste for the lionfish instead of the grouper. With this, he refers to a necessary decrease in the grouper catch.
Scientific director of Carmabi, Mark Vermeij emphasized several times in the past that the grouper is almost entirely ‘extirpated due to over-fishing’ on Curaçao. The lionfish is no match for a full-grown grouper but it can handle the immature ones because it can eat a fish equal to its physical length. The Nassau bass (a kind of grouper) is a solitaire saltwater fish found in a tropical climate. The species is mainly found in coastal waters, open sea, at coral reeves and in waters where the bottom is covered with sea grass. “As only a small number of natural enemies of the lionfish are known, it is exiting to discover that the Caribbean grouper is capable of controlling them. Previous studies demonstrate this because lionfish (upon dissection) was found in the stomach of the grouper,” according to Mumb
Mumby et al (2011) Grouper as a Natural Biocontrol of Invasive Lionfish. PLoS ONE 6(6): e21510.
Tuesday May 3rd 2011 – Sponge competition may alter reefs
Sponges are a group of common and diverse aquatic creatures, very abundant in coral reefs where they are an important part of the ecosystem. But new research has found that if the balance is disturbed, sponges can alter the potential recovery of reefs in the long term. Featured on Planet Earth Online, 3 May 2011, by Sara Coelho. 
Coral reefs are home to many species and are probably the most diverse habitats on Earth. ‘Corals are the bioengineers of these systems, providing the habitat for many species of algae, fish, crustaceans or sponges,’ says Manuel González-Rivero, a PhD-student from MSEL.
Reefs are also an extremely competitive environment: ‘Space is a critical resource in the marine world, and all organisms compete for space to some extent,’ González-Rivero explains. In recent years scientists have found that some reefs alternate between coral or seaweed dominated environments, depending on local conditions. ‘Climate change affects the balance between these alternate states with modern regimes of disturbance selecting for quicker growing, weedy species,’ says González-Rivero. But the equilibrium might be affected by a third party: sponges.
Sponges are one of the oldest groups of animals existing on Earth. They evolved about 650 million years ago, well before the invention of paws, antennae or wings. Nowadays, they are extremely common and diverse, especially in coral reefs where sponge diversity can be anywhere between 200 to 600 species.
Sponges are generally benign; they provide homes for small animals and plants, and help to support the reef by cementing corals and rubble. But some species, dubbed the excavating sponges, erode the matrix of the coral for a living and may cause actual damage to the reef structure.
González-Rivero, with Laith Yakob and Peter Mumby, wanted to understand how sponges affect the seaweed-coral balance. To do that, they developed a mathematical model to describe the competition between these three groups. The model considers rates of growth, coral erosion and grazing of sponges and seaweed by fish. ‘The interaction represented by our model refers to physical contact, where algae typically overgrow their competitor, coral resist the advance of their competitor by means of defending tentacles, and sponges successfully avoid their defences and overgrow coral,’ says González-Rivero.
The results, reported in the journal Ecological Modelling show that sponges can indeed become dominant and out-compete the corals at a moderate to high rate of overgrowth, especially if grazing by fish and competition with seaweeds is low. This scenario becomes likely if the coral reefs are disturbed by constant and high loads of nutrients, which upset the balance in favour of the sponges. ‘Suppressing the growth of coral bioengineers will compromise essential ecosystem services such as habitat provision for other species,’ says González-Rivero, adding that ‘our study points out the need to include important space-occupying species, such as sponges, in ecological models of reef systems.’
González-Rivero M, Yakob L, Mumby PJ (2011) The role of sponge competition on coral reef alternative steady states. Ecol Model 222:1847-1853 pdf
Tuesday January 18th 2011 – Smaller corals take the heat
New Australian research has found coral reefs will survive warmer ocean temperatures brought on by climate change – but they will be very different.
Professor Peter Mumby and Dr Laith Yakob from the University of Queensland report on their findings this week in the Proceedings of the National Academy of Sciences that small short lived corals which are taking over from large corals in some parts of the world are more resistant to disease.
For several decades, marine researchers have observed warmer sea temperatures devastate large, ancient corals such as staghorns (Acropora) and boulder or dome corals (Montastraea), particularly in the Caribbean. In many areas, these corals have been replaced by smaller, faster growing corals such as Porities and Agaricia.
“It’s like having an oak tree forest replaced by a forest of scrubby young plants,” says Mumby.
But a model developed by the two researchers, and based on a 10-year study in the Caribbean, has shown diseases would not spread as quickly or kill as extensively in the small fast lived corals in that area.
Why do small corals cope better with disease? Mumby says that for an outbreak to occur, a coral colony must survive for long enough to become infected and in turn infect other colonies. In short-lived colonies, the disease does not have enough time to spread.
The model used data on a series of outbreaks of ‘white plague’ in the Caribbean. This disease can kill in a matter of days as the infection creeps across the surface of the coral, destroying tissue as it goes.
The researchers emphasise that the research is only based on Caribbean corals. The small corals of the Indo-Pacific, including the Great Barrier Reef in Australia, have high rates of disease transmission and so the findings may not apply there.
“It almost sounds like a good news story but it isn’t really,” says Mumby. “Having reefs built by these small corals is not a good thing – they support less fish.
“We don’t want reefs dominated by these corals. But we want to make the most accurate predictions we can so we can give policy makers the right advice on how things are going to change.”
Commenting on the paper, Professor Bette Willis from James Cook University says large, complex corals provide better habitats for associated reef fish and invertebrates.
“We know that following bleaching, we see a dramatic decline in coral-associated fish and invertebrates that depend on large branching corals. They live among the branches and seek protection, so you need that three dimensional complexity for habitat diversity.
“One question is whether [new] coral assemblages will provide the same habitat for reef fish and invertebrates. If small encrusting corals take over, the lack of habitat complexity means that we are likely to see very different coral reef communities. [They] will also have implications for other ecosystem services like coastline protection.”
Mumby says their findings are a ‘cautionary tale’ to other scientists.
“We can’t blindly apply what we know and extrapolate into the future. If we want to give realistic predictions and protect the benefits that people derive from those sorts of reefs, we have to have a good understanding of how those reefs are going to behave,” he says.
“As we transform ecosystems through climate change, they become completely new and novel ecosystems. We can’t apply the lessons of the past.”
Tuesday November 23rd 2010 – Ocean acidification and coral settlement
Christopher Doropoulos (MSEL) is at Heron Island to undertake experiments investigating the effects of increasing CO2 on coral settlement, early growth and survival. Chris is working in collaboration with Alicia Crawley (Global Change Institute), who is investigating zooxanthellae uptake and shuffling under conditions of ocean acidification. Currently, the two have set up the experimental ocean acidification system, collected a suite of beautiful, gravid Acropora colonies, and now they sit and wait for the spawning (in the rain, and the wind, without power)…
Friday 19th November 2010 – Introducing Marine Man and the Oceanauts
It’s a matter of life or depth… Introducing Marine Man! A new comic by a friend of Pete and MSEL, Ian Churchill is due to be released in comic book stores worldwide shortly. Issue one features a a focus on a real life marine biologist – Peter J Mumby:
Read Ian Churchill’s blog or visit his website for more about the comic, release dates and about Marine Man.
Monday 15th November 2010 – Khaled Bin Sultan Living Oceans Foundation Prepares for Launch of Four-Year Global Reef Expedition in 2011
Having recently observed its 10th anniversary, the Khaled bin Sultan Living Oceans Foundation is preparing for its next scientific research and education project, the Global Reef Expedition, which will launch in 2011 and continue through 2014. The primary scientific goals of the Expedition are to map and characterize coral reef ecosystems, identify their current status and major threats, and examine factors that enhance their capacity to resist, survive and rapidly recover from major disturbance events. The resulting scientific findings will be shared freely with participating countries and scientific and regulatory organizations, and will be used by countries for developing sound management strategies for coral reefs.
During 2011, the Expedition team intends to conduct coral reef surveys in the Bahamas and other countries within the Caribbean region. In 2012, current plans are to conduct research on the coral reefs of French Polynesia, Australia, and other Pacific coral reef regions. The Expedition team also will conduct education programs in all of the participating countries and regions, which will include the involvement of local educators and students on board the ship. Additionally, multi-media technologies will be used to bring the ongoing research into students’ classrooms, and coral conservation curricula will be developed for use in schools worldwide during the Expedition. (Read More)
Monday 15th November 2010 – Ocean acidification up at Heron Island Research Station
Chris Doropolous is at Heron Island Research Station until late February 2011 looking at the effects of ocean acidification on recruitment and juvenile stages of coral growth. More updates as work progresses.
Biases in fish surveys highlighted by distances of detection
A recent study led by Yves-Marie Bozec (MSEL postdoc) together with researchers from the French Institute of Research for Development (IRD), and Agrocampus Ouest in France, investigated the ability of SCUBA divers to detect fish during underwater visual censuses (UVC). Using the distance sampling method, they show that most fish actually flee before being detected, thus introducing major bias in fish surveys.
Distance sampling is a widely-used technique for estimating the abundance of wildlife populations. It involves the assessment of distances at which a species is detected perpendicular to a reference line. The distribution of distances reflects the probability of detecting a species at any distance: a perfect detectability implies that the number of detections is constant as distance increases. In New Caledonia, researchers from IRD have performed distance sampling-based UVC since the mid 1980′s, thus producing a large database of detection distances for more than 500 fish species. Their analysis reveal that fish detection for a given size and behaviour is more likely to occur at a particular distance from the transect line.
For most fish, the number of detection increases with distance, indicating evasive movement of fish prior to detection. The distance of maximum detection correlates with body size, so that the larger the fish, the greater the fleeing distance. Furthermore, species classified as “shy”, independently from their size, flee at farther distances. Inversely, cryptic and camouflaged fish are hardly detected beyond 1 meter.
On coral reefs, fish are usually surveyed using strip transects, whereby every fish detected within the strip is counted. This technique assumes that the probability of detecting fish at any distance is, at best certain, at least uniform within the boundaries of the strip. Distance data show how this assumption is violated when using a particular strip width, and how much density estimates can be consecutively affected. Of particular concern is that the magnitude of biases (such as evasive movements) may be inconsistent over time and among reefs. In addition, ecological studies aiming at comparing surveys that used different strip widths are likely to produce misleading results. The present study calls for more research on UVC techniques in order to reduce inconsistent biases in fish density estimates.
indicates that ocean acidification decreases coral settlement and coralline algal cover by 50%. Surprisingly, the only preferred settlement substrate in natural conditions was avoided by coral larvae as ocean acidification increased. These results suggest that ocean acidification may interfere with coral population recovery by reducing coral settlement rates, disrupting settlement behaviour, and reducing the availability of the most desirable substrate for successful coral recruitment.