Archives par mot-clé : Reefs

Rise and fall of the Great Barrier Reef

by University of Sydney, May 28, 2018 in ScienceDaily


Over millennia, the reef has adapted to sudden changes in environment by migrating across the sea floor as the oceans rose and fell.

The study published today in Nature Geoscience, led by University of Sydney’s Associate Professor Jody Webster, is the first of its kind to reconstruct the evolution of the reef over the past 30 millennia in response to major, abrupt environmental change.

The 10-year, multinational effort has shown the reef is more resilient to major environmental changes such as sea-level rise and sea-temperature change than previously thought but also showed a high sensitivity to increased sediment input and poor water quality. (…)

Bleaching of coral reefs reduced where daily temperature changes are large

by University of California – Irvine, April 26, 2018 in ScienceDaily


By taking a closer look, scientists find resilience in face of heat stress.

Coral reef bleaching is stark evidence of the damage being inflicted by global climate change on marine ecosystems, but a research team has found some cause for hope. While many corals are dying, others are showing resilience to increased sea surface temperatures, pointing to possible clues to the survival and recovery of these vitally important aquatic habitats (…)

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Oceanic plastic trash conveys disease to coral reefs

by B. Friedlander, January 25, 2018 in CornellChronicle


“Plastics make ideal vessels for colonizing microscopic organisms that could trigger disease if they come into contact with corals,” Lamb said. “Plastic items – commonly made of polypropylene, such as bottle caps and toothbrushes – have been shown to become heavily inhabited by bacteria. This is associated with the globally devastating group of coral diseases known as white syndromes.”

When plastic debris meets coral, the authors say, the likelihood of disease increases from 4 to 89 percent – a 20-fold change. The scientists estimate that about 11.1 billion plastic items are entangled on reefs across the Asia-Pacific region, and that this will likely increase 40 percent over the next seven years.

A ‘marine motorhome for microbes’: Oceanic plastic trash conveys disease to coral reefs

by Cornell University, January 25, 2018 in ScienceDaily


Plastics make ideal vessels for colonizing microscopic organisms that could trigger disease if they come into contact with corals,” Lamb said. “Plastic items — commonly made of polypropylene, such as bottle caps and toothbrushes — have been shown to become heavily inhabited by bacteria

Shoreline Change in Atoll Reef Islands

in Friends of Science, December 2017


This study gives irrefutable evidence on the persistence of atoll reef islands in French Polynesia over the last five decades, as 92% of the 111 islands studied exhibited either areal stability or expansion since the 1960s. Only 8% of the 111 islands showed contraction in area. Tropical cyclone waves contributed to island upward growth, which reached up to 1 m in places, through the transfer of sediments up onto the island surface.

Retrograde Accretion of a Caribbean Fringing Reef Controlled by Hurricanes and Sea-level Rise

by P. Blanchon et al., October 12, 2017 in Front.Earth.Sci


Predicting the impact of sea-level (SL) rise on coral reefs requires reliable models of reef accretion. Most assume that accretion results from vertical growth of coralgal framework, but recent studies show that reefs exposed to hurricanes consist of layers of coral gravel rather than in-place corals. New models are therefore needed to account for hurricane impact on reef accretion over geological timescales

Prof Peter Ridd: the Great Barrier Reef recovers, our science institutions are failing us, science needs to be checked

by Alan Jones, interviews peter Ridd, July 28,  2017 in JoNova


Corals have a little thermometer built in them, when you take a core of them from many years ago we know what the temperature of the water was back when Captain Cook sailed up the coast, it was actually about the same temperature then. It was colder 100 years ago, but it has recovered from that. The temperatures on the reef are not even significantly warmer than average on a hundred year timescale.

Corals that bleach in one year will be less susceptible to bleaching in following years

‘Perfect storm’ led to 2016 Great Barrier Reef bleaching

by James Cook University and Université Catholique de Louvain, July 3, 2017, in ScienceDaily


Professor Wolanski said the study was subjective to the extent that there was a lack of oceanographic field data in the Great Barrier Reef itself for the 2016 el Nino event. By contrast, the amount of oceanographic field data in the Torres Strait and the northern Coral Sea was very good.

“What we presented is our best-informed attempt to reveal the mechanisms involved in causing the event, based on the available oceanographic data combined with the existing body of knowledge on the water circulation in and around the Torres Strait/Northern Great Barrier Reef region.”

CLIMATE ALARMISTS WON’T ADMIT THEY ARE WRONG

by Clives James, The Australian in GWPF, June 6, 2017


Actually, a more illustrative starting point for the theme of the permanently imminent climatic apocalypse might be taken as August 3, 1971, when The Sydney Morning Herald announced that the Great Barrier Reef would be dead in six months.

After six months the reef had not died, but it has been going to die almost as soon as that ever since, making it a strangely durable emblem for all those who have wedded themselves to the notion of climate catastrophe.

Densely Aggregated Corals Maintain Calcification Under Ocean Acidification Conditions

by N.R. Evensen and P.J. Edmunds, 2017, J. Exp. Biology


Regardless of the actual mechanism responsible for the densely aggregated corals to maintain calcification rates in the face of ocean acidification, the study of Evensen and Edmunds, in their words, offers “a compelling case for differential densities of branching coral colonies (i.e. aggregation types) mediating the sensitivity of coral communities in at least some habitats” and it further supports “recent indications that neighboring organisms, such as conspecific coral colonies in the present example, can create small-scale refugia from the negative effects of ocean acidification” And that is more good news for those concerned about the future health of these important marine ecosystems.

Stony corals more resistant to climate change than thought

by Rutgers University, June1, 2017 in SienceDaily


Stony corals may be more resilient to ocean acidification than once thought, according to a Rutgers University study that shows they rely on proteins to help create their rock-hard skeletons.

“The bottom line is that corals will make rock even under adverse conditions,” said Paul G. Falkowski, a distinguished professor who leads the Environmental Biophysics and Molecular Ecology Laboratory at Rutgers University-New Brunswick. “They will probably make rock even as the ocean becomes slightly acidic from the burning of fossil fuels.”

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Dead zones may threaten coral reefs worldwide

by Smithsonian Tropical Research Institute, March 21, 2017


Dead zones affect dozens of coral reefs around the world and threaten hundreds more according to a new study. Watching a massive coral reef die-off on the Caribbean coast of Panama, they suspected it was caused by a dead zone — a low-oxygen area that snuffs out marine life — rather than by ocean warming or acidification.

Journal Reference: Andrew H. Altieri, Seamus B. Harrison, Janina Seemann, Rachel Collin, Robert J. Diaz, Nancy Knowlton. Tropical dead zones and mass mortalities on coral reefs. Proceedings of the National Academy of Sciences, 2017; 201621517 DOI: 10.1073/pnas.1621517114